Online program Overview Session: NSS-13

Abstract

The COMET Cylindrical Drift Chamber is a large, low-mass gaseous detector. Gas exchange through the detector volume affects gas quality, gain stability, and wire aging, which are important for stable detector operation. Increasing the gas-flow rate in a once-through operation would increase fresh-gas consumption and cost, and would also impose constraints on exhaust handling from the experimental area. For this reason, a gas circulation system is adopted. At the same time, safe  operation of the chamber requires the differential pressure between the chamber volume and the surrounding atmosphere to be maintained within a narrow range, because the large-radius, low-mass inner wall adopted to suppress backgrounds imposes a strict mechanical limit on the allowable differential pressure. Pressure excursions caused by pump operation, environmental variations, or abnormal exhaust conditions must be suppressed. While the system consists of standard gas-system components, their configuration and operating parameters were quantitatively evaluated against the mechanical constraints and gas-flow requirements of the chamber. A simplified analysis based on a resistance-compliance model was introduced to interpret  pressure propagation in the gas system. Preliminary gas-system commissioning tests, including pump-start and exhaust-transient measurements, were performed to characterize the pressure response and to evaluate the roles of buffer tanks and restricted flow paths. The results are being used to define the buffer-tank configuration, emergency-exhaust conductance, pump operating conditions, and a staged gas-commissioning procedure, enabling safe commissioning and stable long-term operation of the detector.

Abstract

In this work, we present a systematic characterization of a 2D-THCOBRA detector operated in pure argon (Ar) and Ar/Xe mixtures (Ar/Xe 98/2, 95/5 and 90/10), exploiting the Penning effect to enhance detector performance. The detector is characterized in terms of gain, energy resolution, linearity, and intrinsic spatial resolution. The addition of Xe to Ar significantly reduces the required operating voltage, with equivalent gains achieved at voltages approximately 300 V lower than those required for pure Ar. The energy resolution improved from 24.4% (pure Ar) to 18.3% FWHM at 5.9 keV (Ar/Xe 95/5 mixture), and the intrinsic spatial resolution improves from 1.8 mm (pure Ar) to 1.5 mm FWHM Ar/Xe 95/5. These initial results demonstrate the strong potential of the 2D-THCOBRA operating in Ar/Xe mixtures for X-ray fluorescence imaging and spectral X-ray imaging applications.

Abstract

A systematic study of the ion-backflow (IBF) contribution of single GEM foils with respect to the hole sizes and geometries is presented. The effective gain and the IBF of single GEM foils in a standard gas enclosure with a 2D strip readout plane were measured, using Ar-CO2 (70-30) gas mixture. The X-ray exposure using ⁵⁵Fe source was performed separately for each foil segment to compare the performance differences of the different hole geometries. A clear dependency of the IBF to the size and shape of the GEM holes was found. The results were compared to simulations using the Garfield++ toolkit. We present that choosing the right foils for a TPC readout chamber can effectively limit the IBF.

Abstract

A compact SiPM–GAGG(Ce) radiation detector without conventional front-end electronics was evaluated for LINAC radioactivation monitoring. The proposed detector employed a simplified signal-processing architecture without a preamplifier, shaping amplifier, or comparator. Spectroscopic performance was evaluated at SiPM operating voltages from 58 V to 61 V. The best energy resolution for the 662 keV photopeak of Cs-137 was 8.31% at 61 V, corresponding to an overvoltage of approximately 7 V from the measured breakdown voltage of 53.88 V. Mixed-source measurements using Ba-133, Cs-137, and Co-60 demonstrated distinguishable radionuclide peaks and channel-energy linearity greater than 0.99. The detector was subsequently applied to LINAC radioactivation measurements, where characteristic gamma-ray peaks of W-187 were successfully detected near the LINAC head after high-energy photon beam irradiation. The results demonstrate the feasibility of compact and simplified LINAC radioactivation monitoring using the proposed detector system.

Abstract

Silicon photomultipliers (SiPMs) are widely used in PET detectors due to their compact size and compatibility with magnetic fields. However, their performance is strongly dependent on temperature. In this work, the temperature dependence of energy resolution in a SiPM-based scintillation detector coupled to a LYSO crystal is experimentally investigated. Measurements were carried out over a temperature range from 10 to 50 degrees Celsius using a controlled climatic chamber. Preliminary results show a systematic degradation in energy resolution with increasing temperature. A simplified physical interpretation based on the temperature dependence of breakdown voltage, gain, photon detection efficiency (PDE), and noise contributions is proposed. Ongoing work focuses on developing a quantitative model and compensation strategies for detector stabilization.

Abstract

Tl-doped NaI (Tl:NaI) single crystal has been a one of the standard scintillators from mid 20^th century, and in this time, we will report a development of transparent ceramic Tl:NaI. Tl 0.05, 0.1, 0.3, and 0.5% doped NaI transparent ceramics were fabricated by the spark plasma sintering (SPS) method. Under X-ray irradiation, these ceramics showed a typical emission wavelength at 420 nm with a typical decay time (~200 ms) due to ³P₁→¹S₀ electronic transitions of Tl⁺. When 662 keV gamma-rays from 137Cs were irradiated, all the samples exhibited a clear photoabsorption peak, and among all the samples, 0.1% doped one had the highest scintillation light yield, reaching to 36000 ph/MeV, which was equivalent to common commercial Tl:NaI single crystal.

Abstract

Organic scintillators are fast detectors that are
sensitive to both neutrons and gamma rays. Measurements of
neutron timing in an intense gamma-ray field can be studied
with thin organics, as recoil electrons produced by Compton
scatters have a path length significantly longer than those of
recoil protons. Past work in characterization of such samples
has been hindered by the lack of clear energy calibration with
samples with thicknesses less than 2 mm, as the spectral features
used for an energy calibration are significantly broadened from
electron escapes. To address this issue, the gamma spectrum was
observed for three gamma check sources, Cs-137, Na-22, and
Co-60, within four organic glass scintillators, from 6 mm to 1
mm, and compared with Monte Carlo models MCNPX-PoliMi. A
genetic algorithm was used to broaden the simulated spectra to
match the measured spectra. Thinner samples displayed greater
broadening of Compton edges, which suggests an increase in
electron escape. Simulations show an increase in electron escape
probability between the 6 mm sample and the 1 mm sample of
12% ± 1% to 26.1% ± 0.3%.

Abstract

In radiographic imaging, dual-layer flat-panel detectors (DFDs) can be used for two purposes: acquiring high-quality x-ray images and performing material decomposition.
A convex combination of the x-ray images acquired from DFD can yield significantly improved detective quantum efficient. The DFD structure consists of stacked upper and lower flat-panel detectors, and can provide different modulation transfer function (MTF) characteristics depending on the orientation of the stacked detectors with respect to the incident x-ray. In this paper, we consider three different stacked structures for DFD and find the optimal DFD structure by experimentally observing the MTF curves using fabricated DFD prototypes. Because the inverted layers have a back-irradiation geometry, the MTF performance is better than that of the normal case. Therefore, we can select a DFD structure having an inverted lower layer to acquire high-DQE x-ray images.

Abstract

We report the development of plastic scintillators for thermal neutron detection by incorporating surface‑modified LiAlO₂ nanoparticles. Conventionally, thermal neutrons have been detected using ³He gas counters, but the scarcity of ³He has driven the search for alternative technologies. Plastic scintillators are attractive due to their low cost and ease of fabrication; however, loading neutron‑reactive isotopes such as ⁶Li into plastics is challenging because conventional organometallic compounds suffer from poor solubility and strong quenching effects.

To overcome these limitations, LiAlO₂ nanoparticles enriched with ⁶Li were synthesized via a sol–gel method and their surfaces were modified with trimethoxyphenylsilane to improve compatibility with a polystyrene matrix. Structural and spectroscopic analyses confirmed that the nanoparticles retained the γ‑LiAlO₂ phase and were successfully functionalized with phenyl groups, without significant changes in particle size. The surface modification greatly enhanced nanoparticle dispersion within the plastic scintillator, as evidenced by uniform elemental mapping.

Abstract

Fast plastic scintillators are attractive for radiation detection owing to their nanosecond decay times, low cost, and scalability; however, their practical application is limited by low scintillation light yield and poor detection efficiency for X‑ and γ‑rays. In this study, we report the development of plastic scintillators loaded with perovskite quantum dots (QDs) exhibiting high photoluminescence quantum yields (PL QYs). Cesium lead halide perovskite QDs with various halogen compositions were synthesized via a facile solution process under ambient conditions. Surface modification using oleyl amine was employed to passivate surface defects and enhance radiative recombination. Transmission electron microscopy revealed spherical QDs with diameters of approximately 10 nm and a narrow size distribution. The oleyl amine modification markedly improved PL QYs, achieving values exceeding 80% for CsPbBr₃ QDs. By tuning the halogen composition, the emission wavelength was controllably varied from ~420 to 540 nm. These high‑PL‑QY QDs were uniformly loaded into polystyrene‑based plastic scintillators. Scintillation spectra demonstrated dominant QD emission without defect‑related luminescence, indicating fast emission owing to the interband transition within the QDs. Although clear full‑energy peaks were not observed in pulse‑height spectra, enhanced scintillation responses were evident for samples containing surface‑modified QDs. These results demonstrate that surface‑engineered perovskite QDs are promising additives for improving the performance of fast plastic scintillators.

Abstract

This work investigates how scintillator geometry influences light collection in 3D-printed plastic scintillators, motivated by the ability of additive manufacturing to fabricate detector shapes that are difficult to realize by conventional casting or machining. Four geometries, including a cylinder, truncated cone, cone, and paraboloid, were fabricated using a digital light processing based 3D printing method and evaluated experimentally. Complementary Geant4 optical-photon simulations were performed to study photon transport and collection trends for the same geometry family. Both experiment and simulation indicate that geometry modifies photon escape, internal reflection, and collection at the readout face. Taking the cylinder as the reference at 100%, the truncated cone, paraboloid-like geometry, and cone show increased relative light outputs of 151%, 156%, and 180%, respectively, suggesting that non-cylindrical 3D-printed scintillator shapes can improve photon collection at the readout face, most likely by reducing unfavorable optical paths and repeated reflections. The simulations reproduce the qualitative trend observed experimentally, although the absolute values do not agree number by number because the present model does not fully include fabrication-specific effects such as print-layer scattering, surface roughness, optical coupling variations, reflector response, and sensor nonuniformity. These results demonstrate that geometry is an important design parameter for additively manufactured scintillators and should be optimized together with material composition and photosensor coupling.

Abstract

In June 2025, Kori Unit 1, the first commercial nuclear power plant in the Republic of Korea, obtained final approval for decommissioning. This milestone highlights the growing need for radiation-imaging technologies that can support radiation surveillance during nuclear decommissioning and in other high-radiation environments. In this study, we developed a portable gamma camera for real-time monitoring of high-energy gamma-ray fields and evaluated its basic detector characteristics and imaging performance. The spatial response of the GAGG-SiPM detector array was investigated using flood-map measurements and line-profile analysis. The obtained flood maps showed that all scintillator pixels were distinctly resolved, with minimal signal overlap between adjacent pixels. The average full width at half maximum (FWHM) was measured to be approximately 0.58 mm, corresponding to about 41% of the 1.41 mm pixel pitch, indicating stable intrinsic spatial resolution across the detector array. The intrinsic energy resolution was assessed using a Co-60 point source. The measured energy resolutions were 7.42% and 6.68% FWHM at the 1.17 MeV and 1.33 MeV photopeaks, respectively. In addition, the detectable imaging distance was examined by acquiring Co-60 point-source images at source-to-detector distances from 10 cm to 300 cm. The source location was successfully identified throughout the tested range, and clear gamma-ray imaging was achieved even at a distance of 3 m. These results demonstrate that the proposed portable gamma camera provides stable detector response, high-energy gamma-ray imaging capability, and practical source-localization performance for radiation monitoring in nuclear decommissioning environments.

Abstract

A SiPM-based detector using GAGG powder-PMMA composite scintillators was developed and evaluated. There were 8 scintillator samples with the identical GAGG mass fraction but different powder grain sizes. Each scintillator has an active area of 40 mm × 40 mm and a total thickness of 3.6 ± 0.1 mm. The detector system consisted of the scintillator module, front-end analog electronics for filtering, shaping, and amplification, and an 8-channel back-end digital acquisition system. Under identical measurement conditions, the count rate measured with a 50 µCi 22Na source increased from approximately 1.7 × 10³ cps for Sample #1 to 1.6×10⁴ cps for Sample #8. Waveform measurements also showed higher output amplitude for the larger-powder sample. The results indicate that the grain size of GAGG powder strongly affects photon transport and effective detector response in the composite scintillators.

Abstract

We studied thermal neutron detection using a LiF/CaF₂:Dy eutectic composite which can be used for thermoluminescence dosimetry. Emissions of the sample due to the self-trapped exciton of CaF₂ and 4f-4f transitions of Dy³⁺ ions were confirmed in the X-ray excited spectrum and decay curve measurements. The thermoluminescence spectrum at 230 ℃ showed only the emission peaks due to Dy³⁺.  This result indicates that Dy-doping in LiF/CaF₂ is efficient for thermoluminescence dosimetry applications. Thermal neutron detection was performed using the LiF/CaF₂:Dy eutectic composite, and its light yield was 3000 photons/neutron. This measurement was achieved due to the fast emission of the self-trapped exciton. The LiF/CaF₂:Dy eutectic composite can act as a dual functional material for radiation dosimetry and detection.

Abstract

Scintillation detectors are widely used in various fields. Since the performance of scintillators directly affects detector properties, the evaluation of scintillation properties is essential. Scintillators are required to exhibit specific properties, including a high light yield, a short decay time, and a low afterglow. So far, afterglow measurements have not yet been standardized, and each manufacturer employs its own measurement setup and evaluation criteria. In conventional systems, their temporal resolution is limited to several milliseconds, which is insufficient for accurate characterization of afterglow in the short-time region. Separately, although near infrared (NIR)-emitting scintillators have recently attracted considerable attention and their emission spectra have been investigated, their NIR decay curves have not been sufficiently evaluated. In this study, we developed the afterglow and NIR decay curve measurement systems by combining a field-emission pulse X-ray source with the two types of detection units: an afterglow detection unit and an NIR detection unit. The performance of the developed system was evaluated by measuring the afterglow of CWO, BGO, and CsI:Tl, as well as the NIR decay curve of the NIR-emitting Yb:Lu₂O₃ transparent ceramics. The afterglow levels of CWO, BGO, and CsI:Tl were approximately 2.5, 0.5, and 450 ppm, respectively. The X-ray-induced NIR decay time constants of 0.1%–3.0% Yb:Lu₂O₃ transparent ceramics were 0.66–1.05 ms. Since these values were comparable to previously reported afterglow levels and PL decay time constants, the present results are considered to be valid.

Abstract

Next-generation radiation detection, such as TOF-PET and high-flux X-ray imaging, requires scintillators that combine high light yield with ultrafast response. However, organic scintillators are often limited by inefficient exciton utilization and non-radiative quenching of high-energy states. In this work, we report a 1D supramolecular organic architecture based on the luminophore TPE-4Br. By shifting the molecular packing from a discrete 0D form into an ordered 1D configuration, we achieve a structural "locking" effect that rigidifies the lattice and suppresses vibrational quenching. This configuration results in an increase in Young’s modulus (6.44 GPa) and hardness (0.24 GPa) compared to 0D crystals. Under X-ray excitation, the 1D framework exhibits an enhanced light yield that is 1.5 times higher. Furthermore, real-time dynamic X-ray imaging at 67 fps is demonstrated, showing minimal afterglow and the ability to track moving objects with high signal fidelity. This combination of luminosity, timing, and mechanical robustness positions the TPE-4Br-based 1D framework as a candidate for high-speed nuclear instrumentation and medical CT systems

Abstract

This work presents the development of a large-area flat-panel scintillation detector designed for prompt gamma monitoring in proton therapy. The detector comprises a 2x2 of ArrayJ-60035-64P silicon photomultiplier arrays, coupled with a 14x14 Lutetium-yttrium oxyorthosilicate crystal array. To address the challenge of high channel density, a diode-based row-column multiplexing circuit was implemented, reducing the total number of readout channels from 256 to 64. The system interfaces with the PETsys TOFPET2 ASIC via a custom adapter board utilizing LSHM-140 connectors. Preliminary laboratory tests using a 22Na point source demonstrate the feasibility of the multiplexing scheme and its potential for high-resolution gamma-ray imaging in clinical environments.

Abstract

When exiting controlled areas such as nuclear facilities, contamination control is of the utmost importance to prevent the removal of contaminants outside the area. Currently used hand and foot monitors and personnel contamination monitors are equipped with multiple detectors near the clothing and limbs, enabling the simultaneous measurement of radioactive contamination on the body surface.

However, conventional detectors make it difficult to pinpoint contaminated areas in detail. Accurately visualizing contamination distribution is crucial for preventing internal exposure and conducting efficient decontamination operations.

This study aimed to develop a personnel contamination monitor capable of visualizing contaminated areas. Contamination visualization is achieved by combining an electron-multiplying charge-coupled device (EMCCD) camera or a quantitative complementary metal-oxide-semiconductor (qCMOS) camera with multiple scintillators, such as ZnS(Ag) scintillators and rare-earth complex high-luminescence scintillators.

This device utilizes a CCD camera (ImagEMX2, Hamamatsu Photonics K.K.) or a CMOS camera (ORCA-Quest, Hamamatsu Photonics K.K.) in combination with a 3.25 mg/cm² ZnS(Ag) scintillator (EJ-440, Eljen Technology), a rare-earth complex high-luminescence scintillator (manufactured by Hokkaido University), and a large-area plastic scintillator containing dispersed europium complexes (manufactured by Hokkaido University). The system was irradiated with alpha rays, and the resulting images were analyzed using ImageJ.

Abstract

Copper-based halide perovskite Cs₃Cu₂I₅ has emerged as a promising lead-free scintillator for ionizing radiation detection. In this work, Na⁺-doped and undoped Cs₃Cu₂I₅ single crystals were grown at room temperature via a formic-acid-assisted solvent evaporation method. Both crystals exhibit ordered diffraction planes and excellent crystallinity, confirmed by rocking-curve full width at half maximum (FWHM) values of 0.009° (undoped) and 0.008° (Na⁺-doped). X-ray photoelectron spectroscopy confirms that Cu⁺ remains in its monovalent state in both samples. Optical analyses show that Na⁺ incorporation enhances the photoluminescence (PL) intensity by 11% and increases the self-trapped exciton (STE) decay time from 1090 ns to 1146 ns, attributed to shallow defect passivation and suppressed non-radiative recombination. The Na⁺-doped crystal demonstrates superior scintillation performance with a light output of 42,000 ph/MeV and an energy resolution of 4.9% at 662 keV, compared to 39,000 ph/MeV and 5.4% for the undoped crystal, corresponding to improvements of ~7.6% and ~9%, respectively. These results establish Na⁺ doping as an effective strategy for defect suppression and scintillation enhancement in lead-free halide perovskite single crystals.

Abstract

Thermal cycling is used to accelerate the ageing process through an exaggerated version of diurnal temperature variations a detector/material may experience during use/storage over the lifetime of a detector. For this investigation, samples of optical grease were thermally cycled between +5 and +75°C in an environmental chamber. Four sets of samples were created with different preparation methods, volumes and substrates used, consisting of: 0.02g between microscope slides, 2ml petri dish, and 1” & 2” diameter discs in petri slides. A total of 15 samples per set were created that were divided into three subsets: Cyclical (C), Duration (D) and Room (R) samples. The percentage transmission (%T) for all samples was measured using a spectrophotometer for a wavelength range of 300-700nm for comparison with the emission range of common scintillators, such as EJ200. Identical “blank” samples with air were used for baseline/zero corrections performed for the spectrophotometer, meaning all %T values are relative to air. C samples were recharacterised at the end of each year equivalent cycle, while D and R were only recharacterised after the final cycle as controls for the removal from the chamber and the passage of real time respectively. Samples were cycled to equivalent of a maximum 20 years, with an additional set of “no bubble” (NB) samples introduced at the start of the 11^th year equivalent cycle to determine the impact of air bubbles on %T. The 1” petri slide samples displayed the greatest average variation in %T across the range 400-500nm, with a drop of 20% %T value between pre and post-20 year characterisation (28% percentage difference), while 2” petri slide samples showed an average 10% decrease in %T value (15% percentage difference). Microscope slides and petri dish samples displayed a 2.6% average %T decrease (3% percentage difference) and 3.9% average %T increase (4.7% percentage difference) respectively.

UK Ministry of Defence © Crown owned copyright 2026/AWE

Abstract

Scintillators are important for a wide range of applications in detection and imaging. In this paper performance of advanced large diameter thallium-based scintillation crystals coupled to silicon photomultipliers (SiPM) are presented. These compounds have high effective atomic number (Z_eff) and physical densities due to thallium present in the crystal structures. These compounds possess many favorable properties for imaging applications, including high energy resolutions (< 5% (FWHM) at 662 keV), primary decay constants of these compounds ranging from 450 to 630 ns, and their light yields between 18,000 and 75,000 photons/MeV. Coupling these crystals to SiPMs makes them into compact and portable detectors, enabling them to be incorporated in many modular detector designs.

Abstract

Scintillators play an important role in radiation detection and imaging. Thallium-doped cesium iodide (CsI:Tl) is one of the major scintillators that have been used for many applications for many decades. Coupling CsI:Tl crystals to silicon photomultipliers (SiPMs) makes them into compact and portable detectors, enabling them to be incorporated in many modular detector designs. This paper presents a performance study of improved CsI:Tl crystals coupled to silicon photomultipliers (SiPMs). Iterations of electronic designs as well as CsI:Tl crystal growth, processing, and characterization with both photomultiplier tubes (PMTs) and SiPMs will be presented.

Abstract

Scintillator energy resolution is ultimately limited by light yield. One theoretical pathway for increasing this light yield in inorganic scintillators is optical re-excitation of activator ions. Lu₃Al₅O₁₂ (LuAG) with Ce³⁺ activator ions is investigated as a candidate for verifying the mechanism. Ca co-doping is used to convert the Ce³⁺ to Ce⁴⁺ during manufacturing, so Ce³⁺ is only present in the material after a radiation interaction occurs, allowing for multiplication of the radiation-induced signal. Optical spectroscopy is used to evaluate the impact of co-doping ratios on the concentration of Ce⁴⁺ in several samples. The impact of
stimulation wavelength on the intensity of previously observed optically-induced valence change indicates the valence change originates from charge-transfer absorption of the Ce⁴⁺. A dual-beam optical and x-ray excitation experiment with a chopperwheel and lock-in amplifier is used to compare the scintillation response of LuAG:Ce and LuAG:Ce,Ca samples to single- and dual-beam excitation. The difference between these responses is evaluated with a lock-in amplifier and using a program which superimposes the single-beam signals and minimizes the variance of this superposition with respect to the dual-beam signal. After optical characterization, the responses of LuAG samples with different Ce concentrations and co-doping ratios will be tested in this dual-beam experiment to identify optimal doping concentrations for re-excitation.

Abstract

The spectroscopy of decay products is one of the three pillars of low-energy beam exploitation techniques produced by the ISOL method. Decay stations can be found in all facilities using the ISOL technique to produce radioactive beams, such as ALTO (France), ISOLDE (CERN), and IGISOL (Finland), as well as in future facilities like SPES (Italy) and DESIR (France), to name a few in Europe.

In the context of β decay, it is important to note that the total energy released during this process, denoted as Q_β, can exceed 10 MeV as we venture further from nuclear stability. At the same time, the energy required to remove a neutron (S_n) decreases, resulting in the emission of unbound neutron(s) alongside the expected γ-rays. 

Elpasolite crystals containing ³⁵Cl such as CLYC:Ce represent a promising way to detect and discriminate both neutrons and γ-rays coming from such decay while measuring their energies. The ANR project SENSE (Scintillating Elpasolite for Neutron Spectroscopy Enhancement) aims to study such crystals using detailed Geant4 simulations in association with experimental measurements. 

We started this project using a 3"x4" CLYC:Ce crystal in order to measure several physical quantities such as its resolution, efficiency and homogeneity. Those measurements were first performed for gamma only and are combined with simulations performed via Geant4 for comparaison. So far, the study of neutron interaction with the crystal is being studied and experiments using ALTO facilities are planned. Also, Geant4 does not implement well the cross-section of neutron interacting with chlorine and this part of the work is still in progress. Our presentation will share the results we have obtained for this CLYC crystal and the on-going work that is performed at IJCLab.

Abstract

We are evaluating the potential of CsPbBr₃ crystals as Cherenkov light generating materials for TOF PET applications. CsPbBr₃, a lead halide perovskite semiconductor, has recently emerged as a highly efficient and cost‑effective alternative to traditional radiation detection materials such as CZT and CdTe for X‑ray and gamma‑ray imaging. Its high carrier mobility and excellent energy resolution characteristics make it attractive for next generation radiation detector technologies. Furthermore, its high refractive index (∼2.4) enables efficient generation of Cherenkov light, positioning this material as a promising candidate for fast timing applications, including TOF PET. To assess its timing performance, we investigated the coincidence time resolution (CTR) of CsPbBr₃ samples. Two crystal sizes—5 × 5 × 10 mm³ and 3 × 3 × 3 mm³—were used to study how crystal length affects CTR. Each crystal was optically coupled to a Broadcom NUV‑MT SiPM (S4N44P014M or S4N66P014M) and irradiated with a ²²Na positron source in a coincidence timing measurement setup. A CTR of ~339 ps was achieved using a pair of 3 × 3 × 3 mm³ CsPbBr₃ detectors. This preliminary result is highly encouraging and demonstrates the strong potential of CsPbBr₃ crystals for fast‑timing radiation detection applications. In this work, we present our initial findings and discuss the associated challenges, along with potential strategies for further improving the CTR.

Abstract

This study presents a comprehensive multi-scale computational and experimental investigation into displacement damage effects induced by high-energy proton irradiation in silicon-based photodiodes. The developed methodology systematically integrates SRIM-based analysis of primary knock-on atom (PKA) energy spectra, molecular dynamics (MD) simulations using LAMMPS to model atomic-level defect formation, and TCAD-based device-level electrical modeling in SILVACO. MD simulations revealed a nonlinear increase in stable Frenkel pair formation, ranging from minimal defects at low PKA energies (≤200 eV) to substantial defect clustering at higher energies (≥500 eV), with approximately 40 stable defects per 2 keV event. These atomistic results were used to inform TCAD models, which demonstrated that increasing mid-gap trap densities significantly amplify reverse-bias leakage currents via trap-assisted recombination mechanisms, consistent with the Shockley–Read–Hall (SRH) recombination theory. Experimental validation using BPX65 photodiodes irradiated with 3 MeV protons, corroborated simulation predictions. Leakage current increased dramatically with proton fluence, exhibiting linear trends at lower fluences. Forward current measurements showed only modest degradation, confirming trap-assisted recombination as the primary mechanism behind device deterioration. The combined results underscore the dominant role of trap-assisted recombination in leakage current enhancement and validate the SRH framework in describing carrier lifetime degradation due to mid-gap traps. Deviations at high fluence were attributed to interface effects and charge compensation mechanisms. These findings demonstrate the effectiveness of integrating atomic-scale simulations with device-level modeling to predict and interpret radiation effects in semiconductor detectors, providing a foundation for future radiation-hardened electronics design.

Abstract

This paper describes a compact charged particles spectrometer called DREAM (French abbreviation of « Détecteur Radiation Energétique Adaptable et Miniaturisé »). It is a cubesat compatible radiation monitor, designed to measure protons (13 MeV – 200 MeV) and electrons (350 keV – 3 MeV) in space, essentially in the Earth’s magnetic field. Built around silicon diode detectors co designed with STEEL Electronique and N7 Consulting, DREAM weighs around 400 g, fits within a 0.6 U volume (55 × 100 × 100 mm), and consumes less than 3W at 5 V. 
The main goal of this instrument is to measure the dynamic behaviour of trapped charged particles flux in the magnetosphere, mainly disturbed by solar flares. It will then help to predict anormal fluxes that may damage satellites or humans in space. Experimental results show a good agreement between simulated and experimental spectra obtained at the UCL (62 MeV beam) and Partrec (184MeV beam) proton accelerators. 
Qualification activities (radiation latch up tests, vibration, thermal cycling in vacuum, …) have been performed in 2025 and a detailed summary will be available in the paper. This instrument is already identified in several missions (mainly for the spaceweather), like the ESA S2P (Space Safety Programme) mission.

Abstract

Cadmium telluride (CdTe) is a leading room-temperature semiconductor for direct X- and γ-ray detection, but its performance is limited by bulk stoichiometric defects and interface-induced leakage current. Here, we report an integrated strategy combining vapor-pressure-controlled CdTe(Cl) crystal growth with noninvasive van der Waals (vdW) Au contacts to enhance bulk charge transport and interfacial charge control. Detector-grade CdTe(Cl) single crystals were grown by vertical gradient freeze using a Cd reservoir to stabilize Cd partial pressure and Cl doping to regulate compensation. This approach suppressed large Te inclusions below 5 μm, achieved ~60% infrared transmittance, and yielded high resistivity of 1.5 × 10¹⁰ Ω·cm, electron mobility of 1055 ± 88 cm² V⁻¹ s⁻¹, and electron mobility–lifetime product of ~1.1 × 10⁻⁴ cm² V⁻¹. Planar Au/CdTe(Cl)/Au detectors showed clear ²⁴¹Am α-particle response. Mechanically transferred Au electrodes further formed vdW contacts that avoided atomic intermixing, preserved surface chemistry, reduced defect-related photoluminescence, and increased the Schottky barrier height from 0.78 to 0.83 eV. Consequently, vdW-contact CdTe detectors suppressed dark current and improved 59.5 keV γ ray energy resolution from 14.4% to 11.8%.

Abstract

We investigated the alpha-particle response of a back-illuminated CMOS imager for radionuclide measurements in nuclear decommissioning. A GSENSE2020-BSI sensor with an approximately 10 μm-thick sensitive layer was used. To prevent alpha particles from reaching the circuit layer, measurements were performed with an 11 μm-thick aluminum foil and aluminized polymer sheets. The alpha-particle energy was varied by changing the number of sheets, and the resulting event images and deposited energy were analyzed. The expected deposited energy was calculated using Geant4, and single events were extracted using OpenCV-based image processing. The image intensity was calibrated to deposited energy using a ²⁴¹Am gamma-ray source.

Alpha-particle events appeared as spatially spread images. Under unsaturated conditions, the measured energy spectra agreed well with simulation, whereas ADC saturation caused underestimation at higher energies. Reliable energy information was obtained when the deposited energy was approximately 1.5 MeV or lower. The event area increased with deposited energy, following area is proportional to E_dep^1/3. These results demonstrate the potential of a back-illuminated CMOS imager for alpha-particle detection and nuclide identification.

Abstract

Silicon drift detectors (SDDs) are promising sensors for high-resolution X-ray spectroscopy because of their low anode capacitance, good timing capability, and scalability to large-area and multi-pixel detector systems. This work presents recent progress on single-pixel and array SDD technologies developed for space astronomy and synchrotron radiation applications. Single-pixel SDDs with sensitive areas from 15 to 85 mm² were designed and fabricated through optimization of the drift field, anode structure, leakage-current suppression, and dedicated semiconductor process. Low-noise front-end electronics, semiconductor packaging, and digital pulse-processing readout electronics were developed to support detector characterization and module integration. A 30 mm² single-pixel detector achieved an energy resolution of 135 eV at 5.9 keV at −40 °C, demonstrating the effectiveness of the device and readout design. Based on these developments, a first 19-pixel SDD module with a hexagonal 1+6+12 layout was fabricated, packaged, and tested for the Spectroscopy Focusing Array of the enhanced X-ray Timing and Polarimetry mission. The module integrates the SDD sensor, ceramic substrate package, low-noise front-end electronics, and high-density flexible readout interface. Low-temperature X-ray measurements showed that most pixels satisfied the energy-resolution requirement, whereas the remaining pixels were mainly limited by increased dark current. The measured spectral response indicates the capability of the module to cover the required 0.5–10 keV energy range. These results validate the feasibility of the developed SDD technology for compact, low-noise, multi-pixel X-ray spectroscopy modules. The next stage will focus on the second-generation 19-pixel prototype and a 7-pixel SDD detector system for synchrotron radiation applications.

Abstract

Lead oxide (PbO) is a promising high-atomic-number photoconductor for direct-conversion x-ray detectors because of its high x-ray stopping power and low intrinsic electron–hole pair creation energy. A key challenge is depositing detector-grade thick PbO layers directly onto flat-panel imaging electronics while keeping the substrate temperature compatible with thin-film transistor and CMOS readout arrays. In conventional physical vapor deposition, limited adatom mobility at substrate temperatures below approximately 200 °C can promote porous, platelet-like polycrystalline PbO with reduced charge collection, temporal lag, and structural instability. In this work, oxygen-ion-assisted thermal evaporation was investigated as a low-temperature route for producing amorphous PbO photoconductors. Low-energy oxygen-ion bombardment supplied additional energy to the growing film surface without increasing the substrate temperature. The deposition conditions were optimized with respect to x-ray-to-charge conversion, evaluated using the average electron–hole pair creation energy, W±​. Amorphous PbO layers with W±​ as low as approximately 7.5 eV/ehp and effective hole mobility on the order of 10⁻¹ cm²/V·s at 10 V/μm were achieved. These results indicate that oxygen-ion-assisted deposition can produce amorphous PbO layers with detector-relevant charge generation and transport properties for direct-conversion flat-panel X-ray detectors.

Abstract

The General Antiparticle Spectrometer (GAPS) is an Antarctic long-duration balloon experiment designed to measure low-energy (< 0.25 GeV/n) cosmic antinuclei as signatures of dark matter. The distinctive GAPS particle identification technique relies on a tracker composed of > 1000 lithium-drifted silicon (Si(Li)) detectors – over 10 m² of silicon sensors – that both captures an incoming antinucleus into an exotic atom and measures the de-excitation X-ray and nuclear annihilation products. The GAPS program established the techniques necessary to produce large-area Si(Li) detectors, operable 150 ^oC above the liquid nitrogen temperatures typically required to achieve fine X-ray resolution, for an order of magnitude lower cost than previous commercially-available detectors. The distinctive detector geometry, together with custom polyimide passivation coatings that protect against humidity and organic contamination, has enabled remarkably robust operation: stable performance has now been demonstrated after more than five years without requiring HV bias or low-temperature storage to prevent lithium redistribution. Detector segmentation, previously achieved through ultrasonic impact grinding, has now been demonstrated using a DISCO dicing saw, a less expensive alternative suitable for mass-production that opens new flexibility in detector and readout geometries. In this contribution, we review the features of such Si(Li) detector design and performance, and discuss the broader applications enabled by custom detector geometries.

Abstract

Neutron measurement technology is essential for the decommissioning of the Fukushima Daiichi Nuclear Power Plant and for monitoring special nuclear materials. In the former case in particular, high-dose gamma radiation is present, and there are significant constraints on size and weight. As a neutron detector suited to these environments, we focused on a neutron detector using silicon carbide (SiC) semiconductors, which offer higher radiation resistance than silicon semiconductors. In this study, we verified whether it is possible to distinguish and detect neutrons emitted from a ²⁵²Cf neutron source from gamma rays in a high-dose gamma-ray background environment. The results showed that it is possible to distinguish between neutrons and gamma rays in a gamma-ray environment of up to 132 Gy/h.

Abstract

High-purity germanium (HPGe) detectors are widely used in high-resolution gamma-ray spectroscopy and high-count-rate radiation measurements because of their excellent energy resolution and detection efficiency. Multi-electrode HPGe detectors can improve count-rate capability and provide local response information, but the calibration and summation of segmented-electrode signals remain challenging due to charge sharing, inter-electrode coupling, crosstalk and transient induced signals. In this work, a coaxial four-electrode HPGe prototype based on amorphous germanium blocking contacts was developed and tested. The detector consists of a small boron-implanted central P⁺ electrode and three outer n-type segmented electrodes defined by amorphous germanium coating and aluminum metallization. The leakage current was below 10 pA at 200 V. Measurements with a ¹³⁷Cs source showed energy resolutions of 1.43–1.45 keV for the outer electrodes and 1.78 keV for the central electrode at 662 keV. Experimental and simulated four-channel waveforms were compared to evaluate induced responses in neighboring electrodes. Non-zero residual baselines observed in the experimental neighboring channels indicate coupling effects in the present frontend design. Simulated ¹³⁷Cs segment spectra and Ch1+Ch2 sum reconstruction further show that the central-electrode energy can serve as a reference for segment-energy calibration. These results demonstrate the feasibility of the amorphous-germanium-contact multi-electrode HPGe design and provide a basis for central-electrode-referenced correction and reliable segment-sum reconstruction in high-count-rate measurements.

Abstract

Compton polarimeters enable the detailed study of polarization sensitivity of fundamental radiative processes in the hard x-ray regime, i.e. for photon energies between 60 keV and 1 MeV. These detectors are based on double-sided segmented planar semiconductor crystals in which the recoil electron and the scattered photon of the Compton process are measured simultaneously. Within the SPARC collaboration (Stored Particles Atomic Physics Research Collaboration), a new Compton polarimeter in telescope configuration consisting of a Si(Li)- and a HPGe-detector has been developed, aiming for polarization experiments at particle accelerators and synchrotron facilities to analyze atomic or nuclear processes. A polarimeter consisting of only the first crystal, the Si(Li), was already operated in stand-alone mode in the energy range starting at 60 keV up to 250 keV. In a study of polarizazion-dependence of elastic scattering at the PETRAIII synchrotron facility of DESY, it proofed to be working well. Now the second crystal, the HPGe, was added to extend the accessible energy range up to the 1 MeV regime to widen the investigation of radiative processes. The main construction of the new detector system was performed at the detector laboratory of the Forschungszentrum Jülich, which is now relocating to the university of Cologne. We will report on the design of the novel Compton-polarimeter and first experimental applications.

Abstract

Mirion has been supplying sophisticated HPGe detectors and instrumentation which are used in cutting-edge materials analysis, fundamental nuclear physics research, and space studies to world’s leading research institutes. The Clover [1] detector is one of Mirion unique product, recognized as an advanced gamma-ray detection system widely used in a variaty of different nuclear physics experiments. Clover detectors consist of four high-purity germanium (HPGe) crystals, arranged in a compact cloverleaf-like configuration within a single cryostat. This unique geometry enhances its efficiency, enabling precise gamma-ray detection and energy resolution. The detectors design minimizes dead space, improving sensitivity to weak signals and increasing the likelihood of coincident gamma-ray detection for advanced spectroscopic studies. The Clover detectors versatility is augmented by its segmented configuration, which allows for effective background suppression and Doppler shift correction, making it invaluable for nuclear physics experiments and high-energy gamma-rays. Recent advancements in signal processing and digital electronics have further enhanced the performance of Clover detectors which continue to be a cornerstone in gamma-ray spectroscopy due to its high efficiency, excellent energy resolution, and timing. This presentation will provide an overview of various technologies for Mirion Clover detectors, highlighting the benefits of recent advancements like electrical cooling, an expanded energy dynamic range, and more.

Abstract

Large-area photodetectors in the form of silicon photomultiplier (SiPM) array detectors are becoming increasingly widespread in basic physics, medical, industrial, and security applications.
Various suitable devices are commercially available from companies such as Broadcom, Hamamatsu, and OnSemi. Alternatively, they can be constructed from individual SiPM devices.
After repeated use and initial testing of self-constructed devices, it is useful to characterize the electrical properties of each SiPM photodetector to determine the operating conditions of the array.
If the operational readout of the photodetector is based on a combination of theoretically available anode signals — for example, by short-circuiting all anode signals into a single readout channel — this verification procedure must be conducted using an independent test system.
This paper discusses the possible general structure of a fully automated test system, its implementation details, and its practical application by the user.
Through the implemented test procedures, the following can be determined:
Short circuits and open circuits on the printed circuit board housing the array under test
The individual I-V characteristic curves of the SiPM devices and the homogeneity of their operating parameters (e.g., breakdown voltage)
The operability, electro-optical conversion gain, response time, and saturation level of the signal of the individual SiPM devices through the injection of optical photons from a light-emitting diode (LED)
Depending on the tests performed, this test system can fully automatically determine the operational status of the SiPM device array within a time interval ranging from a few seconds to about ten minutes.

Abstract

Magnetron sputtering is a widely used technique for depositing both metallic and insulating thin films on diverse substrates. Its strength lies in the precise control it enables over film thickness and morphology, achievable through a detailed understanding of key physical processes such as gas ionization, plasma behavior, target sputtering, and film deposition. This level of control is particularly critical for high-energy physics detector technologies, where thin, uniform, and functional coatings such as those implemented in hybrid Resistive Plate Chambers are essential for optimizing detector performance, stability, and signal fidelity.

A promising pathway toward improving this control is the investigation of plasma-emitted light, which encodes valuable information about the composition, density, and dynamics of both working gas species and sputtered material. However, existing studies have largely relied on external optical observations or diagnostic techniques that perturb the plasma, limiting their effectiveness.

To address these challenges, we developed a high-precision, multi-parameter optical monitoring system capable of probing plasma emission directly within the sputtering chamber. The system samples light at key locations along the target-to-substrate trajectory with a timing resolution of up to 320 ps. Quartz optical fibers are integrated into the vacuum environment and coupled through a dedicated feedthrough to an external detection system. Signal acquisition is performed using Silicon Photomultipliers mounted on a custom-designed readout board.

This approach provides detailed insight into the temporal and spatial evolution of magnetron plasmas, enabling improved understanding of thin-film growth mechanisms. These results will contribute to the optimization of coating processes for next-generation detector systems in high-energy physics, enhancing their performance, robustness, and scalability.

Abstract

This paper reports on the recently deployed ISIS Digital Data Pipeline, which has facilitated an in-depth examination at the detector signals coming from the suite of Muon Spectrometers. Signal processing and event-mode analysis has been used to understand the afterpulsing characteristics of three types of photosensor; the HAMAMATSU R5505 1-inch PMT, the EMI-9954 2-inch PMT and S13360-1325PE HAMAMATSU SiPM. The R5505 was found to produce significant afterpulsing that can be identified via pulse shape discrimination due to their characteristically shorter fall time. This indicates impurity ionization, as the signals are not convolved with the scintillation response. The data pipeline has been tuned to suppress the afterpulses, producing data sets without this background contribution.

Abstract

In high-energy physics detectors, Silicon photomultipliers (SiPMs) operated in mixed radiation fields show a dramatic increase in dark count rate (DCR), which affects detector performance. This work investigates whether the DCR of the SiPMs in the LHCb Scintillating Fibre Tracker can be used as an in-situ monitor of accumulated radiation exposure. The DCR at three delivered luminosities was recorded at the end of three consecutive yearly shutdowns and converted to area-normalized DCR. The results obtained were compared with radiation estimators obtained from particle-transport simulations using the latest detector geometry. The study focuses on total ionizing dose and 1 MeV neutron-equivalent fluence, which represent ionizing energy deposition and displacement-damage effects, respectively. The measured DCR was fitted as a linear function of each radiation estimator. Both estimators show a monotonic correlation with the measured DCR. The fitted slopes are approximately Gaussian after normalization, with relative dispersions of about 17 percent when all tracking stations are combined and about 13 percent when the stations are treated separately. This reduction indicates that part of the response spread is associated with station-dependent effects rather than with channel-to-channel variations only. The two radiation estimators cannot be uniquely separated with the present dataset. The results therefore support an empirical parameterization of DCR as a proxy for the considered radiation estimators, rather than a unique identification of the underlying damage mechanism. With appropriate station-wise calibration, this approach could provide a way to estimate the accumulated total ionizing dose or 1 MeV neutron equivalent fluence from post-shutdown DCR measurements.

Abstract

Single-photon avalanche diodes (SPADs) are advanced semiconductor photodetectors that operate in Geiger mode, offering single-photon sensitivity and sub-nanosecond timing resolution for biomedical and space applications where robust radiation hardness is essential. In these environments, prolonged gamma-ray irradiation causes total ionizing dose effects, in which holes generated in silicon dioxide become trapped near the silicon/silicon dioxide interface, forming positive oxide-trapped charges and promoting interface trap formation. The progressive accumulation of these charges distorts the local electric field distribution near the guard ring periphery, causing field crowding that can promote premature edge breakdown and compromise stable Geiger-mode operation. This work employs technology computer-aided design (TCAD) simulations using the Sentaurus tool to compare a conventional virtual guard ring structure with a proposed physical guard ring realized by a deep p-well, available in complementary metal-oxide-semiconductor (CMOS) processes. Simulation results demonstrate that the virtual guard ring exhibits persistent edge field crowding exceeding the device junction field across all irradiation conditions, whereas the physical guard ring maintains its edge field below the junction level over a wide irradiation range. These results confirm that the deep p-well-based physical guard ring effectively reduces the risk of premature edge breakdown, offering a promising radiation-tolerant design strategy for CMOS SPADs.

Abstract

The ClearMind project aims to improve Time-of-Flight Positron  Emission Tomography by developing detection modules with  a Coincidence Time Resolution of 100 ps FWHM or better.  This performance is achieved through  the simultaneous detection of Cherenkov and scintillation photons  within the PWO crystal window of a Micro-Channel-Plate PhotoMultiplicator Tube  read out by transmission lines.  The first prototype,  assembled by Photek (UK), demonstrated the feasibility of such  technology but has a suboptimal time resolution of 370 ps (FWHM)  when detecting 511 keV gamma photons.  To address these challenges, we are improving the photocathode design,  with the next prototype to be assembled by Incom (USA).  As a first step, we evaluated the performance of standard Incom’s  High-Resolution Photon Detector (HRPPD) MCP-PMT  with a capacitive readout.   Tests were conducted using both a pulsed laser   in single-photon mode and a ²²Na radioactive source. The HRPPD’s  capacitive readout system, which is compatible with the ClearMind’s transmission  line design, has achieved a single-photon Transit Time Spread as  low as 50 ps (FWHM) for high-gain events and a spatial resolution  of about 1 mm (FWHM).    Photocathode deposition on PWO trials at Incom remains stable over time and  confirms its feasibility.  Through realistic simulations combined with machine learning-based  reconstruction, we investigate the factors limiting the time  resolution in ClearMind technology and demonstrate that a time  resolution below 100 ps is achievable for large-size PWO modules under  certain conditions.

Abstract

Fast-timing γ-ray spectroscopy based on LaBr₃(Ce) scintillators coupled to photomultiplier tubes (PMT) is a well-established technique for measuring lifetimes of excited nuclear states in the picosecond-to-nanosecond range. In this work, we present a comparative characterization of different LaBr₃(Ce) crystals of various sizes and geometries coupled to several Hamamatsu PMT models: R9779 (H10570), R13089 (H13719-Y006 and H13719-Y007), and R13408-Y006. The study focuses on timing performance, linearity, and energy resolution using digital signal processing. While the discontinued R9779 remains a benchmark for timing performance, the newer PMT models exhibit good linearity, comparable energy resolution for a given crystal, and competitive coincidence time resolution.

Abstract

The Silicon Vertex Tracker (SVT) of the EPIC detector adopts a serial powering scheme to distribute electrical power to Monolithic Active Pixel Sensors (MAPS) that are mounted on outer barrels, and electron and hadron end caps. Serial powering is an advantageous powering scheme because it reduces the mass required by electrical services. This is important in order to achieve the target material budget in staves and disks, which can be as low as 0.25% X/X₀.

The Shunt Low Drop Out (SLDO) voltage regulator is key to the serial powering scheme. Four SLDOs are connected to each MAPS to supply its 4 different power domains. This forms a coherent electrical unit that is repeated in a serial chain. A constant current is distributed through the SLDOs in this serial chain.

The SLDO is a bespoke circuit design. It supplies up to ~1.0 A of output current with an output voltage in range 1.1 V to 1.4 V. The chip was designed in a 110 nm process. 

A series of SLDO chips were irradiated at the X-ray Irradiation Facility at Daresbury Laboratory (UK). X-rays were produced via Bremsstrahlung from electrons hitting a Tungsten target. The irradiation campaign studied the circuit response against the Total Ionising Dose (TID) requirements of the EPIC detector. The target TID for EPIC-SVT is estimated to be of the order of 200 krad(SiO₂), integrated over a period of 10 years of operations. This estimate is based on a worst case scenario where a beam of 100 GeV electrons collides with a beam of 275 GeV protons for a period of 6 months per year. 

TID irradiations characterised the performance of the SLDO chip for different settings of input voltage, output loads, and different temperatures. Irradiations were carried out at different dose rates, as high as ~100 krad(SiO₂)/min. Annealing was monitored after irradiation.

Abstract

In contradistinction to conventionally manufactured radiation-hardened devices, which demonstrate radiation tolerance and reliability, commercial off-the-shelf (COTS) devices may exhibit vulnerability to single-event effects (SEEs) resulting from direct ionization in environments dominated by protons, such as in low earth orbit (LEO). The issue of limited cross-section data availability for such protons with low energies has been addressed by a dedicated SEE, particularly single-event upset (SEU), evaluation field based on a 1MV tandem accelerator. In the present study, low-energy proton beams with an energy range of between 0.40 and 1.65 MeV have been irradiated to 90-nm COTS SRAM. The proton-induced SEU cross-sections were found to be several orders of magnitude lower than the predicted values through the Weibull plot derived from conventional data. Moreover, an approximate tenfold enhancement in SEU cross-section was observed at the energy of 0.447 MeV, coinciding with a roughly twofold increase in accumulated fluence. The findings present novel experimental insights into the energy- and ion-species- dependent mechanisms underpinning SEU occurrence in COTS.

Abstract

Abstract—Traditional radioactive source testing involves health risks, regulatory limitations, and operational inconvenience. To address these issues, this paper presents a nuclear-like signal generator capable of reproducing the waveform, amplitude, and timing characteristics of real nuclear radiation signals. The proposed system is implemented on a Xilinx K7 FPGA and supports parameter configuration through a touch screen, USB, Ethernet, or host computer software. In the waveform-generation module, photon emission timing is modeled according to scintillator light yield and decay time, while photoelectric conversion jitter and Gaussian pulse responses are introduced to synthesize realistic macroscopic waveforms. In the amplitude-generation module, a cumulative distribution function threshold table derived from measured energy spectra is used to reproduce statistical energy distributions. In the timing module, event occurrence is modeled as a Poisson process with exponentially distributed intervals. The system supports multiple radioactive sources and scintillator materials, including Na, Cs, LYSO, NaI, CsI, and BGO, with independent dual-channel output capability.

Abstract

Ensuring reliable RF operation in radiation-prone is critical for wireless monitoring systems in nuclear and space applications. This work presents a radiation-hardened-by-design (RHBD) voltage-controlled oscillator (VCO) implemented in a 28 nm Fully-Depleted Silicon-On-Insulator (FDSOI) process and experimentally evaluated under total ionizing dose (TID) conditions. The proposed RHBD VCO is compared with a conventional design up to 370 kGy(Si) using a Cobalt-60 gamma irradiation source at KAERI. Measurement results demonstrate that the RHBD VCO significantly improves frequency stability, achieving up to 57% reduction in frequency drift compared to the conventional counterpart. In addition, enhanced output power stability and reduced supply current variation are observed under irradiation. The results highlight the combined benefits of FDSOI technology and circuit-level hardening techniques, demonstrating a robust solution for radiation-tolerant RF circuit design.

Abstract

R-2R ladder converters in nuclear instrumentation are vulnerable to total ionizing dose (TID) because threshold-voltage shifts in NMOS switching transistors perturb on-resistance ratios that govern ladder accuracy. Preliminary irradiation measurements motivate a circuit-level solution: a modest on-resistance increase already drives worst DNL beyond 1 LSB. The proposed converter in 0.18 µm BCD employs a two-layer hardening strategy. The first layer uses a switch-compensated R-2R topology where all resistors share the same R+Ron unit, canceling Ron in the transfer function. The second layer preserves this cancellation through branch-local diode-replica biasing: a per-branch source-tracking loop and a scaled NMOS replica enforce uniform VGS,Ref on every dummy switch, with a constant-transconductance reference anchoring gm,rep to a poly-silicon ratio. Simulations across multiplicities 5–50 at 27 ℃ and 200 ℃ show the proposed converter achieves the 1 LSB target at multiplicity 15 vs. 40 for the conventional reference (2.7× area reduction). At multiplicity 20, worst DNL is 0.564 LSB at 200 ℃ vs. 2.471 LSB, with ~4.4× major-carry DNL improvement.

Abstract

The next generation of imaging atmospheric
Cherenkov telescope (IACT) cameras is transitioning to silicon
photomultipliers (SiPMs) due to their stability, robustness, and
superior sensitivity compared to PMTs. Specifically, we are
developing an ASIC for the advanced SiPM camera (AdvCam).
This ASIC, designated as PRESSEC (Preamplifier Readout Electronics
for Summing SiPMs Enhanced Circuit), is implemented
in 65 nm CMOS technology. The PRESSEC utilizes a 32-
input scheme for large-area sensor readout. Its primary function
is to generate analog outputs by summing signals from four
sensors into a single channel, effectively reducing the total output
count to eight channels. The main functionality of this ASIC is
housed in the energy path, which integrates a single-ended-to-differential
converter and a pole-zero cancellation circuit. This
structure is instrumental in reducing the pulse’s Full Width at
Half Maximum (FWHM) to 3 to 5 ns, thereby mitigating pileup
effects in high activity environments. Simultaneously, these
signals feed a trigger system for rapid event identification via a
fast comparator. Additionally, a dedicated Night-Sky Background
(NSB) monitoring circuit is included to measure ambient noise
from sources like moonlight, employing a slow integrator with
adjustable high-value pseudo-resistors to achieve integration time
constants in the order of the milliseconds. Rigorous performance
benchmarks, validated using Hamamatsu and FBK SiPMs, show
a signal-to-noise ratio of at least 5, a dynamic range of 300
photons, and a linearity error below 3% for both energy and NSB
paths, while presenting a power consumption of approximately
10 mW per input channel.

Abstract

This work presents a concept and feasibility study of a data readout circuit topology for a pixel matrix with in-pixel digitization, enabling continuous wave-mode X-ray detectors operating at MHz frame rates. The key components comprise dedicated high-speed column and row serializers based on custom-designed flip-flops with an optimized timing scheme. The readout topology is tailored to interface with silicon photonics electronic-photonic integrated circuits, enabling high-bandwidth and scalable data transmission. For a 64×64-pixel configuration, simulations confirm achievable frame rates of up to 4.5 MHz with the proposed architecture. At 1.125 MHz, the total readout circuitry consumes 100 µW per pixel at a supply voltage of 1 V. Design trade-offs in area, speed, mechanical integration and power consumption are analyzed, demonstrating the modularity of the architecture for high-frame-rate detector systems.

Abstract

The experimental characterization of MAGIC (Multichannel Analog Gamma- ray detection Integrated Circuit) is here presented. This ASIC is designed in CMOS 110 nm technology and it is intended to readout the current signals coming from SiPMs coupled with monolithic scintillators that are used in medical imaging applications. The circuit is divided into three main sections: an energy path that provides a differential voltage 
proportional to the energy of the gamma photon, a timing path that gives information about the time of arrival of the photon, and a validation path for event discrimination. For the experimental characterization two PCBs, a mainboard and a carrier, have been designed. In this testing phase all the functionalities have been validated and the key performance of the ASIC have been characterized, in particular the power dissipation (5 mW/channel), the linearity of the energy chain to demonstrate the direct proportionality between the measured charge and the one generated by photon interaction, and the time jitter which affects the propagation delay through the timing path. The results are within the specifications and confirmed by simulations: the linearity error is below 1% and the time jitter is below 20 ps. Such a low value enables its use also in TOF-PET applications.

Abstract

Many low-temperature detector experiments require a maintainable replacement for the warm Multi-Channel Electronics used for time-division multiplexed (TDM) readout of superconducting quantum interference device (SQUID) amplifiers. This work presents a modular warm TDM readout platform whose architecture replaces the MCE backplane model with a common FPGA carrier, pluggable analog front ends, simple 12 V board power, and commodity network interfaces. The carrier hosts 16 two-channel fast DACs for 32 waveform outputs and an eight-channel 125 MSPS ADC. In a column-readout configuration, the fast DACs provide SQUID Series Array (SSA) feedback, Stage 1 SQUID (SQ1) bias, and SQ1 feedback for eight columns, while the column front end provides SSA bias, transition-edge sensor (TES) bias, and amplification of SSA return signals. In a row-select configuration, the same carrier drives 32 fully differential analog outputs that support two-level row and chip selection. Shared firmware provides timing distribution, configuration, data streaming, and communications, while role-specific firmware implements row-select sequencing or column ADC processing with SQUID flux-locked-loop feedback. Multiple carriers with attached front ends form scalable readout groups. One carrier in each group is configured as the coordinator and provides the SFP+ 10 Gb/s Ethernet interface to the back-end DAQ and configuration system. The platform has demonstrated 1 MHz row rates with 80 active rows.

Abstract

This work presents the design and preliminary experimental validation of an ASIC developed as a test vehicle toward a comprehensive cryo-CMOS process development kit (PDK) for a commercially available 28\,nm bulk CMOS process. A CMOS device array utilizing a row-column addressing architecture for rapid characterization of nearly 2000 NMOS and PMOS devices with different geometries and threshold-voltage flavors, has been fabricated and experimentally validated. The complete transistor array can be evaluated using only 16 external wires, making the platform easily adaptable in a dilution fridge for deep-cryo testing. Separate gate-bias control of unselected devices is implemented to minimize leakage current, while a 4-wire sensing scheme improves measurement accuracy. The large-scale cryogenic characterization enabled by this approach represents an important step toward the development of accurate cryo-CMOS PDKs and reliable IC design methodologies for high-energy physics (HEP), quantum computing, and other cryogenic applications in deeply scaled CMOS technologies.

The fabricated die comprises 13 subarrays covering 10 device flavors, including NMOS and PMOS transistors with high-, regular-, low-, and ultra-low-threshold voltage options, native as well as deep N-well NMOS devices. In addition, duplicated regular-Vt arrays are included to evaluate intra-chip process variations. An integrated scan chain selects one transistor at a time, with all remaining device gates independently biased to suppress leakage during measurement. Preliminary results confirm correct scan-chain operation and successful device selection, with measured I_d - V_{gs} characteristics showing expected current scaling across different device geometries. Comprehensive cryogenic characterization from 77K down to mK temperatures is planned as the next step toward completing the cryo-CMOS PDK.

Abstract

This work presents an in-situ total ionizing dose (TID) characterization of a 2.56 GHz charge-pump phase-locked loop (PLL) implemented in a commercial 55 nm CMOS process for high-energy physics front-end clocking applications. The chip was irradiated with X-rays up to 100 Mrad(Si), while phase noise, integrated jitter, supply current, and lock status were monitored throughout dose accumulation. Although the endpoint degradation is limited, with the RMS jitter integrated from 1 kHz to 10 MHz increasing from approximately 550 fs to 700 fs after 100 Mrad(Si), the in-situ measurements reveal a more critical intermediate-dose effect. Around 10 Mrad(Si), the PLL exhibits strong close-in phase-noise instability, mainly from 1 kHz to 100 kHz offset frequency. Standalone VCO measurements show no similar fluctuation, indicating that the observed behavior is unlikely to originate from the LC-VCO and is more consistent with radiation-enhanced low-frequency noise in the loop-control path. These results show that final-dose measurements alone may underestimate the worst-case phase-noise degradation of PLLs under TID exposure.

Abstract

Multi-electrode High-Purity Germanium (HPGe) detectors are promising for high-count-rate gamma spectroscopy, but traditional JFET readouts suffer from excessive power (~200 mW per channel, >3.2 W for 16 channels), bulky volume, and severe outgassing. This paper presents a low-noise, high-integration readout ASIC implemented in TSMC 0.18μm CMOS, featuring 18 P+ and 18 N+ channels. Each channel consists of a continuous-feedback charge-sensitive amplifier (CSA), a CR-RC shaper employing ICON cells (1 GΩ equivalent resistance) for large time constants, and a class-AB buffer. A PMOS-input folded-cascode topology is utilized for optimal noise performance. Room-temperature measurements demonstrate a total power consumption of 594 mW (180 mA @ 3.3 V) for all 36 channels, presenting a significant advantage over JFET solutions. The ASIC achieves a gain of 11.3 mV/fC, an integral non-linearity (INL) < 1% over 40 keV to 1.5 MeV, and a rise time of ~65 ns. With a 10 μs shaping time, the equivalent noise charge (ENC) is approximately 58 e⁻ at zero input capacitance. Future work will focus on cryogenic evaluation with HPGe detectors and noise slope characterization.

Abstract

We present the design of a low-noise and low-offset bandgap reference (BGR) circuit intended for front-end readout ASICs for semiconductor radiation detectors (SRDs). To suppress low-frequency noise and reduce process-induced dispersion of the reference voltage and proportional-to-absolute-temperature (PTAT) current, a voltage-domain BGR architecture employing local positive feedback is designed [1]. The circuit technique suppresses the dominant noise and offset contributions originating from the error amplifier. Compared to a conventional topology operating at the same power consumption of 50 μW, the proposed circuit achieves a tenfold reduction in low-frequency noise. The circuit is implemented in a 180 nm deep N-well CMOS process from amsOSRAM and operates from a 1.8 V supply voltage, occupying a total area of 0.024 mm². Post-layout simulation results show a tenfold reduction in the 1/f noise, a voltage power spectral density of 200 nV/√Hz from 100 Hz up to 1 MHz and a DC accuracy of 0.06 %. In addition, the proposed BGR achieves a temperature coefficient of 30 ppm/^◦C over the temperature range from -40 ^◦C to 125 ^◦C.

Abstract

Achieving 100ps FWHM coincidence time resolution (CTR) in time-of-flight positron emission tomography (TOF-PET) is benefited by electronics that can resolve individual scintillation photons with high temporal precision. We report a proof-of-concept readout in which silicon photomultiplier (SiPM) single-photon pulses are discriminated by a high-speed comparator and digitized directly by GTY transceivers of a Xilinx Virtex  UltraScale XCVU095 FPGA (VCU1287 board) at 16Gbps, encoding photon arrival times as bit positions with 62.5ps resolution. Signal integrity analysis showed that an initial LVDS comparator produced common-mode voltage and differential swing below GTY receiver specifications; switching to a CML comparator substantially reduced bit errors. Room-temperature SiPM dark count bitstreams were captured with a random FPGA clock trigger and post-processed to produce a finger plot showing 1-, 2-, and 3-photoelectron peaks, providing a preliminary validation of the bitstream-based photon-counting concept. These results support the feasibility of FPGA gigabit transceivers as scalable digitizers for single-photon pulse streams in next-generation TOF-PET detector modules.

Abstract

This work presents a Phase-Locked Loop (PLL) integrated in 28 nm Bulk CMOS HPC+ technology, developed within the INFN Ground-up iNITiative for Electronics developments (IGNITE) project. It is designed to generate low-jitter clock signals at 40 MHz for high-time-resolution charge measurement, and at 640 MHz for high-speed data serialization.
In High Energy Physics, mixed-signal circuits must withstand severe radiation damage, both cumulative, in the form of Total Ionizing Dose (TID) up to 1 GRad, and event-driven, in the form of Single Event Effects (SEEs) induced by particles with Linear Energy Transfer (LET) values up to 60 MeV·cm²/mg. To address these effects, the PLL was implemented using radiation- hardened-by-design-oriented  techniques. Experimental validation in time and frequency domains confirmed cycle-to-cycle jitter values of 11.437 ps RMS and 1.95 ps RMS for the 40 MHz and 640 MHz outputs, respectively. Power consumption is 8.4 mA from a 900 mV supply. The total active area is 0.0174 mm².

Abstract

PIP-II at Fermilab features a brand-new, 800 MeV leading-edge Linear Accelerator (Linac) that will enable the Fermilab complex to deliver more than a megawatt of beam power to the Long Base-line Neutrino Facility (LBNF), requiring a robust Machine Protection System (MPS) to prevent beam-induced damage to delicate cryomodules and vacuum components. Signals in various accelerator components, in both analog and digital format, are collected and processed to assest the operating conditions of the accelerator. In the situation a potential damage is foreseen, the beam permit signal will be drop. A critical element of this system is the fast Analog Machine Protection System, a high-bandwidth platform designed for real-time beam loss monitoring. The system utilizes a modular, FPGA-based architecture to digitize signals from beam-sensing devices, such as AC Current Transformers (ACCTs), non-invasive Ring Pickups (RPUs) and beam scrapers. To eliminate both high frequency as well as 60 Hz noise that might be picked up in the industrial environment, data processing schemes beyond regular digital filtering are planned and implemented.

Abstract

In the context of tomographic imaging, a simple and modular readout combines non-gated charge-to-time converters (QTC), composed of few discrete analog components, and time-to-digital converters implemented in FPGA. The choice of discrete QTC's architecture depends on a compromise between number of components per channel, charge RMS resolution and dead time. Because temperature drift can lead to high measurement error and temperature compensation circuit costs lot of surface per channel, another key parameter to consider is the QTC's response stability to variation of temperature. This study compares three continuous-reset QTC topologies, named after their feedback circuit (RC, diode, and MOSFET). Each circuit is implemented with discrete components and tested in a dynamic range from 2 pC to 35 pC, for a Single-Photon Emission Computed Tomography (SPECT) application. Unlike previous work, we compare them on conventional figures of merit and also evaluate their TOT-Q characteristics stability for temperature variation over 20 °C. Experimental results show that the RC QTC reduces dead time by a factor of 2 compared to linear designs, while the diode-QTC and MOSFET QTC achieve sub-0.1pC charge RMS resolution. However, the MOSFET QTC exhibits a 1.2 %/°C relative error due to temperature-dependent drain current. And diode-QTC requires a temperature compensation circuit to remain stable as RC-QTC (<0.2 %/°C).

Abstract

The Advanced Gamma Tracking Array (AGATA) spectrometer consists of 180 high-purity germanium detectors, each segmented into 38 segments. The trigger rate of each detector can go up to 50 kHz. The data transfer rate per detector ranges from 5 to 8 Gbps. Moreover, continuous monitoring data is sent over the network using another link, resulting in a total outgoing data rate of approximately 18 Gbps using User Datagram Protocol (UDP). The total transfer rate of 180 detectors can go up to 3.2 Tbps during a period of 1 to 3 weeks of continuous operation. The bay is designed in parallel with the Phase 2 front-end electronics development and production so that the complex readout system from these electronics to the computer farm is validated. The 10 Gbps UDP transfer is not totally secure; at such a data readout speed, the computer receiver uses most of its processing and memory capacities. The bay simulates the Phase 2 electronics data readout of more than 12 AGATA detectors using the Serial Transfer and Readout over Ethernet (STARE) modules. The bay is designed to validate the complex readout system from the Phase 2 electronics to the computer farm and to test the overall data acquisition system reliability. Data quality is mandatory for the scientific results, and any data loss could degrade the physics case and the system efficiency. This article will show how the bay simulates the multiple-source data readout to the computer farm at over 100 Gbps.

Abstract

CPRE64 is a 64ch readout ASIC specifically optimized for three-dimensional position-sensitive Cadmium–Zinc–Telluride (CZT) detectors, developed from the CPRE32 . The chip is capable of reading both cathode and anode signals, allowing it to match pixelated,  virtual Frisch-grid CZT or silicon detectors. Each channel integrates a low-noise charge-sensitive amplifier (CSA), high-order shaper, peak detect-and-hold (PDH) circuit for energy measurement, and sample-and-hold circuit for timing measurement. Power consumption is below 5 mW per channel. The ASIC incorporates a layout designed for SEE hardening, resulting in a die area of 7.10 mm × 12.44 mm². The chip layout features pins on three sides for permitting expansion to 128 channels . Experimental results show: when a CZT sensor connected and biased, the electronic resolution better than 150 e⁻(rms) for anode channel, better than 250 e⁻(rms) for cathode channel. The readout channel exhibits linearity with ≤1.5% integral nonlinearity, with a maximum dynamic range reaching 350 fC. Spectral measurements applying a simple depth correction demonstrated a single-pixel resolution of 0.78%(FWHM) at 662 keV.

Abstract

We have developed an application-specific integrated circuit (ASIC) to read out high-purity germanium (HPGe) strip detectors, which will be used as the front-end readout for the HPGe double-sided strip detectors flown aboard the Compton Spectrometer and Imager NASA Small Explorer mission. Here we present an overview of the ASIC, focusing on its fast timing capabilities. The ASIC has 32 channels, each of which contains two shaping circuits to allow for high-resolution measurements of both the charge collected, which is proportional to the energy deposited, and the time of collection. By taking the difference between the charge carrier arrival times on each side of the detector, we can determine the interaction depth in the detector. We evaluated the performance of the ASICs using engineering models of the COSI flight boards. To assess the timing performance in particular, we used a dual-channel function generator to pulse two ASICs, with one channel delayed from the other by various amounts. We also present preliminary measurements of the ASIC timing performance on a COSI-like detector using a fan beam collimator placed to illuminate discrete depths.

Abstract

Advanced X-ray sources such as synchrotrons and Free Electron Lasers (FELs) enable ultrafast time-resolved experiments, requiring acquisition systems with event-by-event timing and spatial resolution. Cross Delay-Line (CDL) detectors are well suited for simultaneous time–space encoding via time-to-space conversion. Standard high-performance architectures rely on Application-Specific Integrated Circuit (ASIC)-based Time-to-Digital Converters (TDCs) or Time-to-Amplitude Converters (TACs), followed by Field-Programmable Gate Array (FPGA) processing, but lack reconfigurability. We present a high-performance, fully FPGA-based reconfigurable acquisition system implementing both the TDC and real-time 3D (x, y, t) reconstruction in programmable logic, eliminating ASIC dependence while maintaining state-of-the-art performance and enabling full adaptability to experimental conditions. The system employs a two-FPGA architecture, with a 8-channel TDC and a dedicated reconstruction unit. The TDC achieves 12 ps rms timing precision, 9.6 ns dead time, and 4 ps integral non-linearity, corresponding to 24 and 27 μm spatial resolution on the CDL for the x and the y coordinates, respectively. This approach enables scalable, high-throughput, fully digital, and reconfigurable time-resolved imaging with spatial and temporal resolution comparable to state-of-the-art ASIC-based solutions.

Abstract

Preamplifiers play a primary role in the resolution, linearity, and sensitivity of ionizing radiation spectrometers, converting the small charges collected by photo detectors into usable voltage signals that are further amplified, digitized, and processed to obtain the intended spectra. Additionally, the accuracy and thermal stability of such charge-to-voltage conversion must be assured to keep a constant performance over time and across different detectors, wiring configurations, and radiation scenarios. This article presents electronic simulations and the first laboratory results showing recent improvements in a new preamplifier designed for High-Purity Germanium spectroscopy systems, in terms of dynamic response, noise, linearity, thermal stability, symmetry, tolerance to reactive loads, piling-up, saturation recovery, and power consumption. The impact of these improvements is also discussed.

Abstract

Correlating molecular neuroimaging with behavior in preclinical models requires acquisitions in awake and freely moving animals, whereas most current positron emission tomography procedures are still performed under anesthesia.
The MAPSSIC project addresses this limitation with an implantable intracerebral probe based on monolithic active pixel sensors (MAPS) for direct positron detection in targeted brain structures of awake, freely moving rats, thereby avoiding the pharmacological bias of anesthesia. Following sensor characterization and simulation studies previously reported, this contribution presents the transition to a fully wireless system. The acquisition chain combines four IMIC2 sensor chips, a STM32L4 microcontroller, 1 Gbit on-board flash memory, and a bidirectional 2.4 GHz radio link to a Raspberry Pi ground station. The complete software stack is implemented in Rust with the Embassy asynchronous framework, providing memory safety and concurrent peripheral management without dynamic allocation. Planned validation with ¹⁸F, ¹¹C phantoms, and anesthetized implanted rats will mark the shift from sensor feasibility to system-level wireless validation.

Abstract

We report a channel-level characterization of a calibrated 64-channel FPGA Time-to-Digital Converter (TDC) for fast-timing TOF-PET, with explicit decomposition of the single-shot precision (SSP) into quantization and jitter contributions. The TDC is implemented on an Altera Cyclone 10 GX device and operates with a 256-tap, 64-bin tapped-delay-line (TDL) at ~400 MHz, calibrated offline via code-density histograms. Two implementation strategies are compared: the default arithmetic carry-chain inference, and a placement-aware variant in which the TDLs are constrained to regular structures. Across all 64 channels, controlled placement reduces the ultra-bin width from 160 ± 76 ps to 101 ± 12 ps, the equivalent LSB (LSBeq) from 83 ± 32 ps to 63 ± 4 ps, and the quantization noise σ_Q from 24.5 ± 7.3 ps rms to 18.1 ± 0.8 ps rms. The placement-constrained implementation also substantially improves channel-to-channel uniformity. The constrained routing increases σ_jitter which makes jitter the dominant SSP contribution once σ_Q is reduced. A system-level projection onto previously characterized UTOFPET monolithic modules indicates that the TDC accounts for 59% of the measured CRT² in a 12 mm LYSO/256-channel module (CRT ≈ 150 ps FWHM), but only ~8% in 16–20 mm BGO/64-channel modules (CRT ≈ 400 ps FWHM). This identifies σ_jitter as the dominant architectural ceiling and motivates wave-union/multi-TDC averaging or finer-node FPGAs for full LYSO exploitation.

Abstract

We have been organizing schools on radiation measurements for students from ASEAN countries. Hands-on experience with radiation measurements is very important, and we prepare radiation measurement systems for practical exercises.

To host as many students as possible, we considered organizing the schools in ASEAN countries. However, the shipping cost of the equipment was extremely high. As a result, we could not conduct hands-on exercises on radiation measurement.

Driven by recent large-scale experiments, electronics for radiation measurements have become compact, highly integrated, and low-cost. This development now makes it possible to carry equipment to schools.

Today, compact detector systems are available at affordable prices, making it much easier to conduct practical radiation measurement exercises in schools.

However, modern compact electronics have introduced a new problem: they are too small to probe easily with an oscilloscope. In modern electronics, waveform processing is increasingly performed digitally. Nevertheless, we believe that analogue processing remains important and highly educational for students. This motivated us to develop electronics specifically for educational purposes.

We have developed an “education kit” for radiation measurement education. By plugging in a SiPM and a small scintillator crystal module, the board functions as a complete radiation measurement system. An on-board FPGA interfaces with a PC through a USB connection. The board is the size of a Raspberry Pi board. Optionally, it can be plugged onto a Raspberry Pi.

Although the board is compact, it provides sufficient space for probing signals. The design of the board will be released as open-source hardware. Students can modify the design and develop their own versions of the board. The “education kit” will serve as an entry point to radiation measurement electronics.

Abstract

The latest version of the low-power 64-channel Front-End readout chip for SiPM Array (FESA4.0) with the preliminary test results is presented in this paper. Using a row-column summing readout method, FESA compresses the 64 input signals into 16 output digital pulses, which then is digitized by the followed field programmable gate array (FPGA). In the pathway of each summing output, there are two threshold current comparators used for signal pickup, one with a low threshold for signal timing and the other with a high threshold for signal validation. Since the signal amplitude is converted into the pulse time-width via the linear discharge method, both the signals timing and amplitude can be measured by the time-to-digital converter (TDC) in the FPGA. The new version of FESA incorporates a time-over-threshold (TOT) measurement capability, which allows to identify the signals originating from different scintillators. The chip offers prominent advantages of simple architecture, low power consumption, and high performance. Through electronics tests, FESA4.0 has a measurement linearity of 99. 1% with a dynamic range of 140. The intrinsic time measurement precision is measured better than 30 ps.  Combined with a TOF-PET detector with an 8×8 LYSO crystal coupled to an 8x8 SiPM, the energy resolution and time coincidence resolution are measured as 279 ps and 12.4% respectively. These test results show that FESA4.0 is very promising for the construction of highly integrated TOF-PET scanners.

Abstract

Atom Switch-based FPGAs (AS-FPGAs) are being developed as next-generation FPGAs with expected high radiation tolerance. Their application to various radiation environments is anticipated, and we are also investigating their potential use in detector electronics for future high-energy physics experiments. In this study, neutron irradiation tests were performed to evaluate the Single Event Upset (SEU) tolerance of digital resources implemented in a 65 nm AS-FPGA. A prototype slow-control board equipped with the AS-FPGA was developed and used for the irradiation test. Two independent block RAM (BRAM) blocks and D-type flip-flop (DFF) blocks were implemented in the FPGA for SEU evaluation, and data mismatches detected during irradiation were counted as SEU events. Neutron irradiation tests were carried out using the tandem accelerator at Kobe University. The neutron fluence reached 1.2 × 10¹¹ n/cm². No SEUs were observed in the DFF blocks, while approximately 10 SEUs were detected in the BRAM blocks. The preliminary SEU cross section for the BRAMs was estimated to be on the order of 10⁻⁹ cm²/Mbit. In parallel with the irradiation studies, stable acquisition of temperature and pressure data from a commercial environmental sensor connected to the prototype slow-control board was successfully demonstrated during neutron irradiation, indicating the applicability of the AS-FPGA to detector slow-control systems in radiation environments.

Abstract

The COMET Phase-I experiment at J-PARC searches for muon-to-electron conversion in muonic atoms, which is a charged-lepton-flavor-violating process. The signal electron is monoenergetic, and its momentum is reconstructed using hit information from the Cylindrical Drift Chamber (CDC) and timing information from the Cylindrical Trigger Hodoscope (CTH). The trigger system must provide high event-selection efficiency, be robust against radiation, return trigger decisions within 8.5 μs, and operate stably. To achieve high event-selection efficiency, a multi-stage hardware trigger system was previously developed in which the CDC and CTH trigger candidates are processed in parallel and required to be in coincidence. However, FPGA reconfiguration in the CDC trigger path could change the communication latency, shifting 10 MHz CDC hit frames and degrading the time consistency required for online track finding. This work reports the development and validation of fixed-latency CDC trigger firmware using a setup with one board of each type. Repeated communication-link reset tests show that the latency is fixed with path-to-path variations less than 1 ns. The total latency is 3.5–3.6 μs, satisfying the requirement with sufficient margin, and input-pulse tests demonstrate 100% trigger response efficiency. These results establish a basis for ongoing full-board CDC validation and CDC–CTH trigger-system integration toward Phase-I data-taking.

Abstract

Abstract— Charge-sharing compensation results obtained with the 3FI ASIC bump-bonded to a pixelated silicon sensor and tested on an NSLS-II synchrotron beamline are presented. The 3FI is a 32×32-pixel readout ASIC fabricated in 65 nm CMOS for Full-Field Fluorescence spectral X-ray Imaging, with 100 μm pixel pitch and event-driven analog output. Building on previously reported functionality and noise performance, this work focuses on the charge-sharing regime. A micrometer-diameter pinhole beam was stepped across pixel boundaries, and event-by-event charge data were recorded at each position. When the beam is directed precisely between two pixels, raw individual-pixel spectra exhibit split-charge events with degraded energy resolution. Offline charge summation of coincident neighboring pixels restores the full photon energy, recovering spectral integrity at the cost of a √2 noise increase. Furthermore, since the shared event is independently sampled by both neighbors, averaging the two reconstructed values cancels the noise penalty entirely, making the detector effectively insensitive to charge sharing across the inter-pixel region. The correction is validated against single-pixel hits recorded away from pixel boundaries, demonstrating full spectral restoration.

Abstract

As unconventional oil and gas exploration extends toward deep and ultra-deep wells, downhole nuclear logging systems are required to operate under high-temperature, high count-rate, and high energy-precision conditions over a wide dynamic range, which are difficult to simultaneously achieve using conventional pulse sampling methods. The multi-voltage threshold (MVT) technique provides inherent advantages under these constraints; however, conventional power-exponential pulse models exhibit limited robustness to waveform variations among detectors of different types and sizes, resulting in degraded pulse reconstruction accuracy and energy linearity. To address this issue, an energy-linearity optimization method is proposed for MVT-based neutron elemental logging instruments. A dedicated front-end signal conditioning and pulse-shaping circuit was developed to regulate the detector pulse shape for improved matching with the power-exponential model, thereby enhancing fitting accuracy. This approach effectively reduces reconstruction error and improves spectral performance across a wide energy range. Experimental results demonstrate that the coefficient of determination (R²) was significantly improved from 0.1380 to 0.9851. The energy resolution was enhanced from 10.5% to 6.2%, closely approaching the oscilloscope-based result of 6.0% with a deviation of only 0.2%. In addition, the proposed method demonstrated good compatibility with detectors of different types and sizes, indicating strong potential for applications in ultra-deep (∼10,000 m) and extreme downhole environments.

Abstract

The COMET (COherent Muon to Electron Transition) Phase-I experiment at J-PARC searches for coherent muon-to-electron conversion in aluminum with a single-event sensitivity of 3 x 10^-15. A key detector challenge is the high instantaneous beam rate, which produces background hits in the Cylindrical Drift Chamber (CDC). In particular, low-energy protons can generate large ionization signals that drive the readout electronics into nonlinear regions, producing waveform saturation and pileups. These effects may reduce hit efficiency by masking later signal or background hits and therefore must be modeled realistically in performance studies. We developed a detector response model for the CDC that combines Geant4-based ionization with the Photon Absorption Ionization (PAI) model, Garfield++-based drift time calculation, and an electronics response emulation based on measured response functions. The model explicitly includes nonlinear saturation effects in the circuit and was validated using cosmic-ray test data. The measured-response model reproduces the main features of the data more accurately than a simple linear-response model. The remaining discrepancy corresponds to a limited uncertainty in the pileup-effect evaluation, providing a realistic basis for COMET Phase-I reconstruction and performance studies.

Abstract

Unmanned aerial vehicles (UAVs) are widely used to estimate ambient dose equivalent rates in mountainous forests. However, improving estimation accuracy remains challenging due to complex terrain and forest structure. In this study, an artificial neural network (ANN) model was constructed using UAV measurement data, and its applicability to estimating ambient dose equivalent rates at 1 m above ground level in mountainous forests was evaluated. In addition, the effect of explicitly incorporating direct and scattered radiation components on estimation accuracy was examined. These results show that the proposed ANN-based approach incorporating physically informed spectral information reduces root mean square error by 23% relative to the conventional Flat Source Model in mountainous forests, with explicit separation of radiation components further improving both estimation accuracy and physical interpretability.

Abstract

Radiation equipment manuals are multimodal documents in which textual content and safety-related visual materials jointly carry critical information. Existing retrieval-augmented generation (RAG) methods are predominantly text-centric and either fail to reflect visual information or include figures unrelated to the answer. This paper proposes a figure-grounded multimodal RAG pipeline that delivers an answer together with its supporting figures. The proposed method comprises figure-to-section alignment via a document map, hybrid sparse–dense retrieval, and answer generation accompanied by relevant figures. To evaluate multimodal performance, we construct an answer-grounded ground-truth figure set and define Figure Precision@k and Figure Recall@k as evaluation metrics. On a benchmark of ten radiation-equipment manuals (800 questions), the proposed method improves Figure Precision@5 from 0.06 to 0.30 and Figure Recall@5 from 0.15 to 0.61 over an image-embedding baseline, with textual answer quality comparable to a long-context text-RAG baseline in BERTScore-F1 and slightly lower in ROUGE-L.

Abstract

Thermoluminescence dosimetry (TLD) relies on accurate glow curve deconvolution to characterise trapping parameters, yet conventional methods are computationally intensive and rely on expert-defined initial parameters. This study explores a machine learning (ML) framework to automate glow curve analysis while preserving interpretability and decreasing user input. A hybrid CNN–GRU model was developed and trained on 658 experimental glow curves from silica glass beads and 10,000 synthetic mathematical glow curves derived from kinetic order equations. The model demonstrates the ability to reconstruct glow curves and infer peak structures without explicit user-defined initialisation, achieving an average figure of merit (FOM) of 8.3% on unseen experimental data. Notably, the ML approach consistently identifies the primary glow peak at the same temperature positions as conventional deconvolution methods, indicating that prominent physical features are reliably captured. Although traditional deconvolution techniques yield lower FOM values (~1%), they require optimisation and expert guidance. However, the ML model provides rapid, repeatable predictions and scales efficiently to large datasets. The results suggest that ML is not a replacement for conventional approaches but a complementary tool, in which ML predicts the initial parameters rather than a user. This work highlights the potential for hybrid ML-physics strategies to advance TL analysis.

UK Ministry of Defence © Crown Owned Copyright 2026/AWE

Abstract

Radiological source search requires timely threat assessment to ensure the security of the public. Existing methods rely on personnel to conduct radiation surveys with mobile detector systems, potentially exposing them to hazardous environments. Recent advancements in physical AI have presented the opportunity to improve radiological source search with robotics, machine learning, and artificial intelligence. Prior work at Oak Ridge National Laboratory (ORNL) has developed a radiation search platform that equips the Boston Dynamics Spot quadruped with a radiation imager, LiDAR, IMU, camera, and onboard computer for real-time 3D radiation imaging during autonomous navigation of complex environments. However, the development and field testing of autonomous robotic platforms are resource intensive and operationally constrained, motivating a simulation framework to refine autonomy algorithms and evaluate search performance across complex environments that would otherwise be infeasible to access. Building on the physical system, this work presents a high-fidelity simulation framework for developing and testing autonomous radiation search workflows in NVIDIA Isaac Sim. The framework centers on a model of the Spot quadruped equipped with simulated contextual sensors, including 3D LiDAR, RGB, and depth cameras, and exposes velocity-command control through a ROS 2 bridge. The current implementation provides end-to-end integration of sensor streaming, command interfaces, and a Python-based autonomy pipeline. Preliminary mapping outputs are presented as qualitative system-integration results and sandbox visualizations to support future autonomy and radiation-modeling studies.

Abstract

Gamma-ray spectroscopy is a fundamental technique for radioisotope identification and quantification across safety-critical applications, where deep learning models have recently emerged as a data-driven alternative to traditional library-dependent methods. However, most existing deep learning approaches operate under a closed-set assumption that all isotopes during deployment are present in the training set; field deployments frequently violate this assumption, and the introduction of unknown isotopes leads to silent degradation. Recent OOD-detection studies have been reported, but they treat OOD spectra as anomalies to be flagged rather than quantified, and systematic evaluation under increasing unseen contaminant complexity remains lacking. This study proposes a denoising autoencoder (DAE) framework that reconstructs the clean target spectrum (¹³⁷Cs, ¹³³Ba) from contaminated measurements while simultaneously estimating target fractions through a dual-head architecture. Using Ce:GPS scintillator pulse data under a leave-one-out unknown noise (LOO-UN) protocol, the DAE achieved a mean absolute error (MAE) of 0.024 at 20% out-of-distribution (OOD) contamination in the two-unseen configuration, outperforming NNLS-known (0.038) and MLP (0.031), with near-constant accuracy as the unseen contaminant count increased from one to two (0.025 → 0.024).

Abstract

Bridging the MeV gap remains difficult due to the interplay of competing photon interaction processes, leaving a persistent sensitivity gap in gamma-ray astronomy. Compton telescopes based on 3D CZT Drift Strip Detectors (DSD) are promising candidates for bridging this gap, offering room-temperature operation, high stopping power, excellent energy and position resolution. A key open question is whether recoil electron tracking, which significantly improves angular resolution and detector sensitivity is achievable from raw detector signals. We investigate this using a machine learning approach trained on forward simulations of the 3D CZT DSD response. Principal Component Analysis of simulated electron tracks confirms that track structure is encodable in a low-dimensional representation, and neural network training to regress the recoil direction directly from detector waveforms is ongoing.

Abstract

Accurate characterization of spent nuclear fuel (SNF) is essential for verifying operator-declared information in nuclear safeguards. Conventional nondestructive assay (NDA) approaches for such characterization based on gamma-ray spectroscopy typically rely on extracting specific photopeak information (ex. 662 keV peak of ¹³⁷Cs), which compresses high-dimensional detector responses into a limited number of variables and may lead to information loss. To address this limitation, we propose a deep learning–based SNF characterization approach that directly utilizes sequential detector-response data for advanced characterization performance. The training dataset was generated through integrated ORIGEN and MCNP simulations for 5000 realistic SNF conditions, covering variations in initial enrichment, burnup, and cooling time. The proposed C2C-GRU-v2 architecture was designed to process long sequential detector-response data by combining Coordinate-to-Context embedding and GRU-based recurrent sequence modeling, enabling both event-level contextual learning and sequence-level generalization. For comparison, a conventional spectrum-based regression method using ¹³⁷Cs peak counts was also implemented under identical conditions. The proposed approach demonstrated improved characterization performance compared with the conventional method, particularly for cooling time estimation, achieving Relative Root Mean Square Errors (RRMSE) of 0.157 for burnup and 0.0456 for cooling time prediction. These results demonstrate the feasibility of deep learning–based sequential detector-response analysis for advanced SNF characterization in nuclear safeguards applications.

Abstract

The 37-element CANDU (CANadian Deuterium Uranium) spent fuel bundles at the Wolsong heavy water reactor are stored vertically in 19 layers within a wet storage facility. The Improved Optical fiber-based VErification System (IOVES), comprising a scintillator, optical fiber, and photomultiplier tube, traverses vertically between bundles to measure radiation profiles. Operators manually count profile peaks to verify bundle integrity, but reliability degrades when peaks are indistinct.

This study presents a Physics-Informed Neural Network (PINN)-based algorithm for automated defect verification of spent fuel bundles. The model learns physical characteristics of radiation profiles to generate predicted profiles, which are compared against measured profiles to localize defective bundles.

A three-head output structure independently predicts the defect status per layer, the number of defective bundles per layer, and the left/right defect probability. The total loss, comprising the three head-specific losses and a mean squared error profile of prediction loss, was optimized using the Adam optimizer.

The dataset comprised three scenarios (0, 1, and 2 defective bundles), with 200,000 samples each, totaling 600,000 samples, split 70%, 15%, and 15% for training, validation, and testing.

Defect classification accuracy per layer reached 99.7%. 19-layer exact match accuracy was 97.2%, with 100% accuracy on defect-free arrays.

This work demonstrates the feasibility of an automated verification system that overcomes operator-dependent inspection limitations. Future work will target improved left/right defect localization accuracy.

Abstract

This work introduces a neuromorphic in-pixel processing concept for next-generation high-flux radiation detectors. By leveraging event-driven principles inspired by Spiking Neural Networks, the proposed approach aims to move part of the signal interpretation directly into the pixel matrix, rather than relying solely on external readout and post-processing. This enables local extraction of photon timing, energy-related features, and mitigation of pile-up effects under extreme photon flux conditions. The concept builds on recent developments in hybrid pixel detectors and emerging intelligent in-pixel architectures, and extends them towards fully event driven detector operation. The proposed paradigm may open new directions for adaptive, low-latency radiation imaging at future synchrotron and XFEL facilities.

Abstract

Micro silica glass jewellery beads have emerged as a viable material for thermoluminescence dosimetry (TLD), offering a low-cost and widely accessible option for personal dose assessment. Their linear glow curve responses, governed by irradiation, thermal conditions, and sample characteristics, exhibit unique spectral elements and structure variability. While machine learning (ML) methods have been successfully applied to dose estimation and irradiation analysis, can ML be used to elevate silica glass beads beyond just decorative jewellery? In this work, a Conditional Variational Autoencoder (CVAE) is implemented to model and generate thermoluminescent glow curves from silica glass beads conditioned on experimental parameters. The model is trained on a dataset of experimentally acquired responses, augmented with Poisson noise to increase the dataset size and robustness. Conditioning variables include temperature profiles, irradiation and sample characteristics, enabling the model to learn relationships between physical conditions and the glow curve. Results show that the CVAE model can generate realistic glow curves that reflect the underlying conditioning variables. Generated predications maintain peak structure and overall shape, while also reproducing the expected linear relationship between total counts and absorbed dose. Model performance remains consistent when evaluated on previously unseen testing data with a mean figure of merit of 7.5%, although accuracy declines at low dose levels due to diminished signal intensity. The proposed approach demonstrates the potential of generative ML techniques for supporting dosimetry simulation, calibration, and data augmentation workflows for future research.

UK Ministry of Defence © Crown Owned Copyright 2026/AWE.

Abstract

In radiation-guided cancer surgery, the amount of radioactive isotopes administered is limited, resulting in the acquisition of low-count, low-resolution gamma images that are further degraded by scattered radiation. In this study, a Residual Convolutional Autoencoder (Residual CAE) was developed to suppress background noise and enhance source-related signals in low-count  gamma-ray images. The input images were zero-padded to  and normalized by the image-wise maximum value. The Residual CAE was configured as an encoder-decoder network with a residual connection that adds the first shallow feature map to the final decoder feature map, thereby preserving source location and spatial details. In test results, the Residual CAE achieved an MSE of 0.0007, SSIM of 0.9682, peak bias of 0.2416 pixels, and  FWHM of 0.0441 pixels. To enable direct deployment of the trained model on the gamma camera and the monitoring software the model was converted to the Open Neural Network Exchange (ONNX) format, allowing its inference performance to be evaluated in an embedded environment. The entire deployment pipeline, including preprocessing, inference, and postprocessing, was implemented. The converted ONNX model produced outputs that were highly consistent with the trained model and demonstrated low-latency inference suitable for real-time gamma-ray image processing. After conversion to ONNX, the model maintained reliable inference performance, achieving a mean peak bias of 1.35 pixels, a minimum ∆ FWHM of −0.711 pixels, and 95.73% overall classification accuracy. These results demonstrate that the Residual CAE is effective for gamma-ray image denoising and source enhancement while preserving source localization and spatial resolution, supporting its feasibility for real-time deployment.

Abstract

This paper presents a neural-network surrogate model for predicting Total Ionizing Dose (TID) induced degradation in a 180 nm bulk CMOS NMOS transistor. The proposed model uses only the gate length L, gate width W, W/L, total dose, and log(1+dose) as input features, where the layout parameters are extractable from a PDK netlist. The model predicts the dose-dependent changes in V_th, I_on, I_off, g_m, and SS. Using 180 nm NMOS data generated by a 3D drift-diffusion TCAD framework, the model is evaluated under three holdout conditions: 15 kGy(SiO₂) interpolation, 50 kGy(SiO₂) extrapolation, and a held-out geometry (L, W)=(240nm, 750nm). With 3-fold cross-validation along the dose axis and five random-seed repetitions, the worst-case absolute relative errors of V_th, I_on, g_m, and SS are below 0.30% in the INTERP/EXTRAP conditions, while those of I_off are 0.99–1.45% and 2.16–2.52%, respectively. In the held-out geometry condition, the worst-case errors of all five metrics remain within 2%, indicating that TCAD-level TID degradation trends can be approximated using layout and total dose variables.

Abstract

This paper describes a deep learning algorithm for the estimation of axial, transverse, and depth of interaction (DOI) positions of detected events in SPECT. The algorithm includes a method for automatic calibration of the gain factor mismatches between detectors. The training data is obtained by simulation. The model consists of three feed-forward networks, one for each parameter to estimate. The axial is a continuous estimate, while transverse and DOI and discrete. The axial estimate is passed as an additional parameter to the DOI estimate, which improves estimates near the detector edge. A single base model is trained with data from a reference detector that is taken to have perfect gains, then calibration learns factors relative to this detector. Log-gains are learned to smoothly enforce strict positivity, from which the gains can be easily recovered. The algorithm achieves an axial FWHM of 1.40 mm, transverse FWHM of 0.83 mm, and a DOI FWHM of 1.24 mm. The gain factor estimates, based on histogram data, are within 0.001%.

Abstract

The estimation of scintillation positioning with a high degree of precision in PET detectors is a crucial factor in determining the spatial resolution of the final image. Nevertheless, intra-crystal Compton scatter, optical diffusion, edge effects, and DOI ambiguity collectively limit the accuracy of first-interaction localization. Consequently, reducing this uncertainty will have a significant impact on the LOR definition and, in turn, will enhance the quality of the final PET image. Machine learning and deep learning methodologies have been shown to be particularly effective in this domain, resolving non-linear relationships between data and often outperforming other traditional approaches. In this study, we investigate various pipelines and deep learning techniques for enhancing gamma-positioning precision through the utilization of validated Monte Carlo simulations in a monolithic PET crystal with a specific hexagonal-shaped scintillation crystal. The validation of the selected models was done using experimental data specifically acquired for this study. The findings suggest that the most effective approach involves the utilization of a net trained with photoelectric and scatter events. The final FWHM mean in the corner and center are 1.2 mm and 1.7 mm for the simulated data respectively, while 1.74 and 2.63 mm, respectively for the validation. The bias achieved was 0.25 mm in the Z direction for the simulation.

Abstract

Characterization of converter layer geometry is critical for determining the absolute detection efficiency of pixelated thermal neutron detectors. However, uncertainties in film deposition and source strength often lead to significant discrepancies between simulated models and actual experimental performance. This work addresses these challenges by implementing a Bayesian optimized FLUKA framework to determine the effective enriched Lithium-6 Fluoride converter thickness for an ADVACAM Timepix3 detector with a 1000 μm Silicon sensor. The FLUKA Monte Carlo model was benchmarked against experimental measurements using an Americium-Beryllium source with a nominal activity of 40 mCi and a documented tolerance of fifteen percent. The Bayesian optimizer successfully converged to an effective thickness of 5 μm after forty evaluations by minimizing the residuals between the nominal source activity and the simulation-implied activities. This methodology demonstrates a robust approach to resolving geometric uncertainties in hybrid semiconductor detectors where direct physical measurement of internal components is not feasible post-assembly. The resulting validated geometry provides a high-fidelity foundation for modeling future detection efficiency benchmarks across diverse neutron spectra. This work demonstrates a practical approach for integrating machine-learning optimization with Monte Carlo transport modeling to address geometric uncertainties in neutron detectors.

Abstract

The author has presented the approach to ambient radiation background pattern recognition and reconstruction for plastic scintillator-based Radiation Portal Monitors during vehicle scanning in situations when the ambient background is depressed (shadowed) by a vehicle. The principle is based on a correlation-significance test derived from the paired Student’s t-tests and Pearson correlation coefficients. The author establishes criteria to recognize background depression and radiation source presence in the occupancy spectrum.

After determining the scale of depression for defined energy windows, the given approach presents the formalism to reconstruct the depressed background during the scan which is based on Aluminum variable thickness sheet as a vehicle equivalent model and the method for evaluating the signal-to-noise ratio to detect the radiation source under such scan conditions.

Abstract

Far-field angular resolution of coded-aperture gamma-ray imagers is often assessed by the smallest angular separation at which two point sources can still be distinguished, but the effect of unequal source activities on such measurements remains unclear. In this work, Monte Carlo simulations were performed to quantify how source-count imbalance influences two-point-source resolution tests in coded-aperture imaging. Images were reconstructed using the maximum-likelihood expectation-maximization algorithm, and reconstruction quality was evaluated using the valley-to-weak-peak ratio and localization bias. An appropriate stopping point was determined by jointly examining both metrics. Under ideal noise-free conditions, increasing source-count imbalance progressively degraded two-source discrimination. When the valid-count mismatch did not exceed 20%, acceptable discrimination was maintained near the nominal angular resolution limit, whereas larger mismatches caused a marked increase in localization bias. These results indicate that source-count imbalance can bias two-point-source resolution measurements and should be controlled in practical evaluations of coded-aperture systems.

Abstract

The geometric cross-sectional parameters of circular tubes, such as cables and rubber hoses, including inner and outer diameters, wall thickness, and eccentricity, are key indicators of manufacturing quality. However, existing X-ray digital imaging-based inspection methods generally rely on locating edge transition points (ETPs) in attenuation profiles, which degrades the accuracy and reliability of parameter reconstruction. To address these limitations, this paper develops a closed-loop residual-driven optimization (CRO) algorithm. The residual at ETPs between the measured projection and the analytical projection of the parameterized contour model is used as the feedback signal, and the contour parameters are corrected through a sign-driven update rule. Monte Carlo (MC) simulation data as the measured data demonstrates that, for a detector pixel size of 0.04mm, introducing CRO reduces the MAE of contour parameters by 69.44%, with a maximum error of 0.03mm.

Abstract

Accurate prediction of radiation exposure for workers during nuclear facility decommissioning is important for radiation protection and work planning. To support this, a previously developed dose assessment program based on the Electric Power Research Institute (EPRI) algorithm was verified in this study. The program inversely estimates source activity from known source positions and measured dose rates at selected locations, and then calculates worker exposure based on the estimated activity. To verify the performance of the program, its results were compared with those from MCNP, a widely used Monte Carlo radiation transport code. Three representative scenarios were considered: (1) multiple workers and multiple sources, (2) presence of thick shielding, and (3) changes in shielding and source location. For each scenario, dose rates were first calculated using MCNP and used as reference values, and the developed program predicted doses under the same conditions. In addition, the Average Fractional Error (AFE) was evaluated by comparing the measured dose rates with the dose rates recalculated at the same points using the estimated source activity. The results show that the prediction error is within 10% for most cases, while the shielding scenario shows a higher deviation, with a maximum error of 18.2%. The AFE results also support this trend, with a maximum value of 34% for the shielding case and less than 6% for the other scenarios, which are within the acceptable range based on the EPRI algorithm criterion. These results indicate that the program provides reliable results overall, while some deviation appears under strong shielding conditions. Since decommissioning environments change frequently, repeated MCNP simulations can be time-consuming. The developed program provides results within a few seconds, allowing quick estimation of worker dose under changing conditions and supporting practical work planning.

Abstract

Tritium monitoring in research reactors is essential for radiation safety because tritium is released as a low-energy beta emitter and is therefore difficult to measure accurately in real time. In particular, the reliability of tritium measurements can be degraded by two major factors: unavoidable statistical fluctuations in the ion chamber output and transient interference caused by radon and its alpha-emitting progeny. Radon-induced alpha events generate large ionization signals in the ion chamber, producing spike-like transients that can distort the measured current, while statistical fluctuations reduce the stability and precision of the monitoring data. To address these limitations, this study proposes a tritium monitoring system that combines a hardware-based alpha suppression function with an AI-based smoothing filter. The proposed monitor consists of two ion chambers, a pump, and a membrane separator, enabling gamma compensation and the exclusion of beta-emitting noble gases. The alpha suppression circuit detects and removes alpha-induced transients before they affect the measurement output. In addition, a piecewise learning-based smoothing filter is applied to reduce statistical fluctuations while preserving the response to actual changes in tritium concentration. The filter employs a two-stage framework consisting of change point detection and local regression, and is implemented using ONNX Runtime in a C#-based real-time monitoring system. Experimental results show that the proposed approach improves both measurement stability and responsiveness, demonstrating its applicability to reliable tritium monitoring in research reactor stack environments.

Abstract

High-purity germanium (HPGe) detector systems are widely used for gamma spectroscopy; however, increasing throughput demands, expanding measurement configurations, and a declining base of expert users have made traditional efficiency calibration and transfer workflows increasingly impractical. Efficiency transfer between counting geometries has historically required manual configuration, custom made sources, and/or execution of Monte Carlo simulations by trained computational physicists, limiting scalability in routine laboratory environments.

We present an approach that embeds Monte Carlo-based efficiency transfer directly within a commercial spectral analysis software stack, enabling automated operation without additional user intervention. At runtime, sample geometries—already specified by laboratory personnel using standard container templates such as Marinelli beakers—are used to drive a ray-tracing-based gamma transport simulation coupled to detector interaction and pulse-processing models. The approach operates over an energy range of 20 keV to 2.5 MeV and produces both full spectra and efficiency curves.

Validation is performed through comparison of simulated spectra and efficiency curves against measured data and results from the Geant4 Monte Carlo toolkit. While not intended to match the full generality of Geant4, the proposed approach demonstrates comparable practical accuracy for routine laboratory configurations while significantly reducing user complexity. Additionally, seamless integration into existing workflows is demonstrated, enabling non-expert users to apply physics-based efficiency transfer without specialized training.

This work provides a scalable solution for automated, high-throughput gamma spectroscopy, bridging the gap between rigorous Monte Carlo modeling and practical laboratory usability.

Abstract

Neutron-based non-destructive assay (NDA) is a cornerstone of nuclear safeguards. Yet conventional techniques relying on integral counting suffer from significant biases if the spatial distribution and emission strength of neutron sources are unknown. This work presents a new, quantitative neutron emission tomography framework using a custom boron-coated straw detector array, enabling simultaneous localization and emission rate estimation of plutonium-bearing materials. Using high-fidelity Monte Carlo simulations and a custom iterative support-refined non-negative least squares algorithm, we demonstrate that centimeter-scale spatial resolution and percent-level accuracy in emission rate reconstruction can be achieved for realistic counting statistics. These results highlight the potential of neutron emission tomography as a next-generation NDA technique for advanced nuclear fuel cycles and reprocessing technologies.

Abstract

Towards the assembly of a virtual component of a radiological monitoring digital twin, an analysis of Caesium 137's mixed field radiation transport is presented. Caesium 137 decays by both beta and gamma radiation which can allow for long range detection of radioactive leakage events. First, a preliminary screening of the source-to-sensor distances of electrons in air was undertaken using the NIST ESTAR dataset. Following this, a Geant4 study was developed to investigate the profile of Caesium 137 activity with respect to distance from a source and threshold variation. This study confirmed that detection efficiency diminished with increased sensor thresholds and confirmed that the change in activity with respect to distance closely follows Poisson statistics. This sets the ground for creating engineering surrogate models that could be employed for application to the radiation field models and the creation of a physical simulation for radiation. The work carried out enables the application of digital twin methodologies to facilitate semi-autonomous radiological monitoring in Nuclear Power Plant environments.

Abstract

Stand-off detection of special nuclear materials (SNM) in safeguards and non-proliferation applications demands imaging systems capable of tracking sources across dynamic environments. In this work, we introduce a Bayesian-Filtering (BF) algorithm for simultaneous  source localization and tracking where existing reconstruction methods, such as simple back-projection (SBP) and maximum likelihood expectation maximization (MLEM), are insufficient. We evaluate the BF algorithm using synthetic data generated with MCNPX-PoliMi for a simulated Compton imager consisting of a 4 x 7 array of LYSO scintillator crystals. Two independent sources are simulated, one sweeping in azimuth and one in elevation, each traveling from -90° to +90° at 1 m/s. The BF algorithm successfully tracked both sources across the full angular sweep, achieving mean angular errors of 6.4° and 6.03° for the azimuth and elevation cases, respectively. Additionally, preliminary results for multi-source tracking are successful with the algorithm tracking both sources up until their paths intersect which is a known challenge we are currently investigating.

Abstract

To address the common issue of channel gain non-uniformity in multi-channel readout scintillation detectors, this paper proposes an iterative correction method based on raw event data.The proposed method requires no additional hardware support and directly calibrates the gain coefficients of each channel directly using event data acquired by the detector. Channel energy data are extracted for each event, and the total energy is computed to locate the photopeak position.An energy selection window is then applied to retain valid events, thereby suppressing the influence of scattered and noise events. On this basis, an iterative optimization process is employed to refine the gain coefficients of each channel, gradually converging the event energy distribution toward the photopeak. The correction effect is assessed by the energy resolution derived from the resulting energy spectrum. Experimental results show that the proposed method effectively compensates for channel response inconsistencies, significantly improves detector performance including energy resolution, and consequently enhances imaging quality and accuracy. The method is simple to implement and highly practical, and can be directly integrated into the data processing pipeline of existing detection systems.

Abstract

This paper presents the development of a compact Geant4-Python simulation-analysis tool for a reproducible gamma response scintillation detector. The tool couples a configurable Geant4 C++ backend with Python automation for macro generation, simulation execution, ROOT-file validation, deposited-energy spectrum generation, count extraction and summarisation in a table. Unlike a general-purpose detector framework, the present implementation is focused on the end-to-end workflow required for scintillation detector response studies using solid cylindrical, hollow cylindrical, and near-4π soccerball-style geometries. Simulations with Cs-137 for 10⁸ events demonstrate the complete workflow, while higher-statistics validation runs on PARAMGanga (Super-Computer at IITR) indicate that the same structure can be extended to larger detector-response campaigns. The resulting tool reduces manual intervention, improves traceability, and provides a reusable starting point for systematic Geant4-based gamma-spectroscopy simulations.

Abstract

The XS ABILITY project aims to deploy a swarm of autonomous unmanned ground/aerial vehicles equipped with advanced radiation detection technologies for Dismantling & Decommissioning operations. As part of this effort, we developed a compact beta/gamma spectrometry chain to monitor concrete surfaces potentially contaminated with ¹³⁷Cs or ⁹⁰Sr, the main fission products encountered in nuclear facilities. The detection system comprises a 4-mm-thick plastic scintillator coupled to a photomultiplier tube, optimized for ⁹⁰Sr/⁹⁰Y full beta energy deposition. Analog signal processing is performed using a wireless, portable multichannel analyzer (CAEN Gammastream), adapted to both payload constraints and real-time measurements. It is currently being integrated into the Sigma Rover for automated floor/wall measurements. Energy calibration and resolution were estimated in laboratory using standard sources (¹³⁷Cs, ²⁰⁷Bi, ²⁴¹Am), complemented by an uncertainty analysis addressing calibration parameters, measurement geometry, and background noise. A Monte Carlo model of the spectrometer was developed and validated against experimental data, facilitating simulations of configurations infeasible in laboratory settings. One of the target test cases of XS Ability being the CEA Marcoule G2 reactor currently undergoing dismantlement, a campaign of automated background noise measurements in the building is scheduled. The analysis of the spatial variability of the signal and the accessibility of the facility are key steps in the development of robust and automated scans. The measures will complement the uncertainty analysis, thus improving the contamination detection and reducing the false alarm and false negative rates. Ongoing work focuses on developing machine-learning-based algorithms for source identification (¹³⁷Cs, ⁹⁰Sr) and localization, targeting both surface and subsurface contamination.

Abstract

The Monte Carlo-based Particle Heavy Ion Transport Code System (PHITS) was used to model deuterium-deuterium (D-D) and deuterium-tritium (D-T) neutron generators for preliminary radiation safety assessment of the ongoing establishment of the Neutron Irradiation Facility (NIF) of the Philippine Nuclear Research Institute (PNRI). Neutron and secondary photon dose distributions were obtained for fully shielded, partially shielded, and unshielded configurations. In both D-D and D-T cases, the counting room dose rates were acceptable with respect to occupational dose limits for a 500-hour annual operating time. However, additional shielding should be explored for the D-T setup to further reduce dose rates in the work area. The dose maps presented the significance of the configuration of moderating and shielding materials in minimizing radiological doses during operation. The findings of this work will serve as a reference for the safe and reliable installation of the country's first neutron generator laboratory.

Abstract

Radiomics analysis in total-body PET imaging is highly sensitive to acquisition variability, particularly count reduction, which directly affects noise characteristics and feature reliability. In this study, we investigate the impact of count reduction and multi-parametric harmonization on the robustness of multi-organ radiomics. A retrospective dataset of 550 patients from two centers was analyzed. Multiple count levels were generated from list-mode data, including standard and reduced counts (reduction factors up to 100). Multi-organ segmentation was performed automatically, and 107 IBSI-compliant radiomics features were extracted from SUV-normalized images. Feature harmonization was applied using ComBat under different configurations, including scanner, voxel size, radiopharmaceutical, and scatter correction. Reproducibility was evaluated using intraclass correlation coefficients across count levels and anatomical regions. Results show that radiomics stability is strongly dependent on both count level and feature type. Approximately 31% of features achieved good reproducibility (ICC ≥ 0.75) in at least one organ. Shape and first-order features remained relatively stable under moderate count reduction (CRF ≤ 20), while higher-order texture features exhibited substantial degradation at extreme count levels (CRF ≥ 50). Harmonization improved feature consistency, particularly for scanner- and resolution-related variations, but had limited impact under severe noise conditions. Taken together, the results indicate that preserving quantitative reliability in low-count PET requires careful consideration of both feature selection and acquisition variability. Rather than relying solely on harmonization, robust radiomics analysis should incorporate count-aware strategies, especially when extending to multi-center or ultra-low-count imaging scenarios.

Abstract

One of the most complex aspects of understanding and simulating accurately micro-channel plate structures is the accurate estimation of surface response of electron impacts, an integral part of the avalanche driven multiplication process that dictates gain and temporal charge profiles. Electron behavior is heavily affected by the surface quality, roughness, material thickness, deposition process and other details that are difficult
to model. For this reason, a lot of groups rely on measurements, which are then introduced in different simulators, such as COMSOL Multiphysics, SimIon or others. Geant4 is the state-of-the-art community-based Monte-Carlo simulation software. Several new physics packages have been introduced over the years to simulate low-energy electron interactions; however, it is very difficult to emulate the entirety of optimizations that can lead to accurate simulation. For this reason we develop an package that allows accurate electron response on surfaces by allowing import of experimental data and is calibrated through an emulation run. The purpose is not to substitute the scatter/back-scatter mechanism that is native to Geant4, but allow light-weight and accurate surface responses to be integrated in full MCP simulations, including multichannel and broad range primary kinetic energies. The model is benchmarked against a fully developed COMSOL model and experimental gain results and tried in various primary scenarios, including direct alpha, beta, beta+ and gamma absorption.

Abstract

Traditional dual-energy X-ray cargo inspection systems are limited in thin-material discrimination and detail visibility because low- and high-energy information is mixed within broad bremsstrahlung spectra. This work presents a multi-energy imaging system based on a 6/3/0.3 MeV three-energy accelerator and dual-layer detectors, enabling acquisition of six effective energy channels in a single scan. Experimental results show that the 0.3 MeV channel significantly improves detail resolution, achieving a wire resolution of 0.9 mm. A random forest classifier achieves 92% overall accuracy for four representative materials over a mass-thickness range of 1–120 g/cm2, outperforming a conventional dual-energy configuration by approximately 28%. These results demonstrate that the proposed architecture is a promising solution for high-precision cargo and vehicle inspection.

Abstract

iThemba LABS has pioneered a mobile gamma-ray detection unit [1] which allows a user to operate in the field and chart the location, strength and energy of gamma radiation. The system incorporates a sensitive scintillation detector [2] typically used for accelerator-based spectroscopy at the SSC laboratory and was integrated into a backpack incorporating a fast 125 MHz digitiser for readout and a GPS enabled Raspberry Pi microprocessor system, allowing in situ measurements of radiation around the Cape Town site, with collected data streamed to the cloud and analysed offline. The Portable African Neutron-Gamma Laboratory for Innovative Nuclear Science (PANGoLINS) project [3] aims to investigate measurements of both gamma rays and neutrons which forms an important component part on site or in transit and the detection of both fissile material for the use in decarbonised energy sources or disposal thereof. A core component of the project is be to miniaturize the weight of the gamma-ray detection device and associated infrastructure so that it can be loaded on an uncrewed aerial vehicle to enable access to, and enhance performance of radiation monitoring measurements at remote sites leading to autonomous operations. PANGoLINS incorporates commercial detector assemblies of LaBr₃(Ce), SrI₂(Eu) and/or CLYC(Ce) for spectroscopy. In addition, the project encompasses the instrumentation of other scintillation detectors with silicon photomultiplier technologies. The coupling of these to readout devices such as high-density ADC readout are planned for applications for nuclear science, medical imaging or astronomy.

Abstract

This paper investigates the feasibility of three-dimensional lithium distribution mapping in solid-state electrolytes by integrating ghost imaging with neutron depth profiling. In the proposed system, a cold neutron beam is spatially modulated by a sequence of 32×32 Hadamard-patterned cadmium masks, and a single-pixel charged-particle detector records the energy spectrum for each pattern. Since each energy bin corresponds to a specific depth layer via the stopping power, reconstructing a lateral image independently for every energy bin and stacking them along the depth axis produces a complete three-dimensional lithium map without mechanical scanning. Monte Carlo simulations were performed with 1024 mask patterns and 5×10⁸ neutron histories per pattern. Images were reconstructed using an untrained neural network-based algorithm at sampling ratios of 25%, 50%, 75%, and 100%. At 100% sampling, the peak signal-to-noise ratio and structural similarity index reached 7.5 dB and 0.577, respectively. Although these quantitative scores remain modest due to limited source statistics, the reconstructed images qualitatively resolve the target lithium-rich structures across all depth layers. Compared to conventional pinhole-scanning approaches that require exhaustive spatial sampling, the proposed method would achieve comparable image quality at 50% sampling, directly halving beam time and making three-dimensional characterization practically feasible.

Abstract

This work evaluated the feasibility of thermal-neutron localization using a directional probe originally developed for gamma-ray source localization. The probe consisted of 30 GAGG scintillator bars surrounding a tungsten cylinder and was modeled by Monte Carlo simulation. Thermal neutrons were generated from a ²⁵²Cf point source placed at the center of a spherical high-density polyethylene moderator. Localization was performed using a centroid vector method based on events recorded within the energy window around the characteristic 80 keV capture-related peak. Ten source directions at a source-to-detector distance of 0.5 m were evaluated under ideal noise-free conditions. Representative results showed the localization accuracy improved as the number of valid counts in the selected energy window increased. The mean angular bias decreased from 4.12° at 100 valid counts to 0.78° at 2700 valid counts, demonstrating sub-degree average localization accuracy at higher count levels. These results support the feasibility of thermal-neutron localization with a compact GAGG-based directional probe and suggest potential future use in simultaneous neutron and gamma-ray localization for nuclear security applications.

Abstract

Spent Nuclear Fuel (SNF) contains various radionuclides and emits significant levels of radiation; therefore, accurate and effective inspection methods for identifying partial defects within SNF are essential. In our previous study, we proposed and fabricated a scintillator-based Gamma Emission Tomography (GET) system named the Yonsei Single-photon Emission Computed Tomography (YSECT). The purpose of this study is to experimentally evaluate the its performance and applicability under conditions mimicking actual inspection conditions. The YSECT system consists of four detection modules, a data acquisition module, a Peltier-based cooling system, and a rotation module. For employing the YSECT instrument to partial-defect inspection, a waterproof test was conducted at a depth of 1.58 m for 120 minutes. In addition, the performance and applicability of the YSECT instrument were evaluated by acquiring projection and tomographic images. The waterproof test confirmed that water intrusion was not assessed into the instrument. While a comparison of projection images obtained in air and water revealed some degradation in image quality—specifically regarding noise levels and spatial resolution—and an exponential decrease in pixel intensities in the inner layers due to water attenuation and lead dummy pins, the source distribution remained clearly distinguishable across the entire SNF region. These results demonstrate that the YSECT instrument is highly effective for detecting partial defects in SNF. Future studies will focus on validating the system under actual SNF inspection conditions.

Abstract

The time-emission profile of delayed neutrons (DNs) emitted by decaying fission fragments and induced by an external, time-modulated interrogating source can be used to identify the isotopic composition of uranium samples. In low- and high-enriched samples, a single isotope dominates the DN temporal profile, complicating measurements of isotopic composition. By suitably moderating the neutron spectrum of an interrogating neutron source, the large thermal fission cross-section of ²³⁵U can be leveraged to amplify its signal, thereby improving the ability to measure lower enrichments. This work evaluates the use of neutron moderation in DN-based enrichment measurements using a Monte Carlo simulation. The ²³⁵U-to-²³⁸U fission ratio serves as the optimization metric, since DN production is proportional to the number of fissions. Optimal moderating configurations that yield a near-unity ²³⁵U to ²³⁸U DN emission ratio for low-enriched and high-assay low-enriched uranium were determined. Based on this analysis, an experimental design has been developed for future validation. DN temporal analysis offers the prospect of nondestructive uranium assay across the entire ²³⁵U enrichment range, from depleted (0.3% ²³⁵U) to highly enriched (93.0% ²³⁵U) uranium.

Abstract

Identification of shielded contraband like chemical weapons, explosives, and drugs being illegally transported in cargo containers can be achieved by detecting gamma rays produced using active pulsed D-T neutron interrogation. The time-dependent active gamma background produced by various low to medium-Z benign cargo-filling materials can interfere with contraband gammas and can make rapid and reliable detection of such contraband challenging. Using optimized timing gates depending on cargo-type for gamma spectra analysis can improve the signal-background ratio of contraband gammas. In this work we use a 6x6 array of 3”x8” NaI(Tl) detectors with coincidence-summing addback for full energy peak reconstruction and a pulsed D-T neutron generator to understand the gamma background produced by empty cargo, and paper and steel cargo filled to 0.6 g/cc density in our cargo inspection setup. We identify optimized timing windows for each cargo and validate the optimization with d_a signal sensitivity calculations.

Abstract

The detection of water in a mock advanced gas reactor slotted can has been carried out using non-radioactive surrogate materials. The method of detecting water is via prompt gamma activation analysis of hydrogen. This results in a prompt 2.223 MeV γ-ray. Due to the absence of hydrogenous materials in the fuel matrix, the 2.223 MeV γ-ray is indicative of the presence of water. GEANT4 simulations of the mock slotted can have demonstrated the variation in 2.223 MeV γ-ray intensity dependent on the location of water. High density polyethylene blocks equivalent to and above water mass detection limits set out in literature were exposed to ²⁵²Cf sources. The γ spectra obtained were examined.

Abstract

A compact handheld alpha–beta radiation detector was developed for field applications in nuclear decommissioning environments. At decommissioning sites such as the Fukushima Daiichi Nuclear Power Plant, mixed contamination from alpha- and beta-emitting radionuclides requires rapid and reliable on-site radiation measurements. To address these challenges, the developed detector enables real-time alpha–beta discrimination while maintaining compact size, lightweight design, and battery-powered operation. The detector employs a Ce-doped Gd 2Si2O7 (GPS) scintillator coupled with a Multi-Pixel Photon Counter (MPPC). Signal processing and radiation discrimination were performed using an FPGA, and the measured count rates and energy spectra were displayed in real time on an LCD via a Raspberry Pi Pico microcontroller. The device weighs approximately 1.3 kg and can operate continuously for up to 8 hours on battery power. Pulse height spectra showed a speak for alpha particles, while beta particles exhibited continuous spectra. The detector achieved a detection efficiency of 90.7% under the measurement conditions. By applying a low-energy threshold (LLD) at channel 190, more than 80% of the alpha counts were retained, whereas the beta counts were reduced to 6.4%, demonstrating effective alpha–beta discrimination. Real-time measurement results, including count rates and spectra, were successfully displayed on the LCD screen. These results demonstrate that the developed handheld detector provides effective alpha–beta discrimination and is suitable for rapid, on-site radiation measurements in mixed contamination environments encountered during nuclear decommissioning activities.

Abstract

We report a proof-of-concept pulsed neutron de- tection experiment using SOFIST3, a silicon-on-insulator (SOI) pixel detector with per-pixel energy and timestamp recording. SOFIST3 was tested at the NOBORU beamline (BL-10) of J-PARC/MLF using a ¹⁰B conversion layer. Two-dimensional spatial distributions of charge signal and timestamp were recorded, confirming simultaneous per-pixel energy and timing measurement under neutron irradiation. The pixel occupancy increased proportionally with beam intensity—from approximately 1.7 × 10⁴ to 5.1 × 10⁴ hits/cm²/s over a factor of ~3 in intensity—demonstrating count rate performance free from the system-wide dead time that limits conventional SOI pixel detectors. These results provide a foundation for developing dedicated high count rate neutron imaging detectors based on SOI pixel technology.

Abstract

Quantification of nuclear material in fuel debris at the Fukushima Daiichi Nuclear Power Station is expected to contribute to the streamlining of processing and management. The Fast Fission neutron Coincidence Counting (FFCC) method has been proposed as a non-destructive assay technique that utilizes fast neutrons, which are less affected by neutron absorbers contained in the debris. In FFCC measurements, an external neutron source is used to induce fission. Compared with conventional D-T systems, D-D neutron generators are more suitable for on-site deployment due to the absence of tritium and the lower neutron energy, which reduces shielding requirements. However, their lower neutron yield and smaller fission cross-sections pose challenges for measurement. In this study, the feasibility of FFCC measurements using a D-D neutron generator was experimentally demonstrated with EJ‑301 liquid scintillation detectors. Time-difference spectra were obtained from uranium samples with and without B₄C neutron absorbers. Clear coincidence peaks were observed in both cases, indicating that fission neutrons can be successfully detected even in the presence of neutron absorbers, with less than a 10% reduction in counts. In addition, Monte Carlo simulations were performed using a designed measurement system to evaluate the feasibility of measurements within a practical measurement time. The results indicate that sufficient counting statistics can be obtained. These results demonstrate the feasibility of the FFCC method using a D-D neutron generator and its potential applicability to the non-destructive assay of fuel debris.

Abstract

Neutron detection plays an important role in nuclear security,  industrial applications, space exploration, and basic science research. Some compact neutron detectors made with ⁶LiF:ZnS(Ag) and wavelength shifters have been deployed in portable instruments for nuclear security. In such detectors where photosensors are attached to one end of the wavelength shifter, high photon propagation efficiency for the wavelength shifter is required so that the signal-to-noise ratio of the photosensor is adequate for signal processing. Monte Carlo simulations using Geant4 were performed to study photon propagation efficiency for wavelength shifter panels and bars. Compact neutron detector modules were constructed according to the results of the Geant4 simulations. An initial test using a ²⁵²Cf source shows the 10x10x45 mm³ bar detects more neutrons than the 10x10x30 mm³ bar and a majority of events have a small pulse height resulting from neutrons detected further away from the photodiodes. Although the count rate of the 45 mm bar for HDPE moderated neutrons was 67% lower than a 10 atm ³He tube, its length is 3 times shorter than the ³He tube.

Abstract

 Accurate quantification of radon (²²²Rn) exhalation rate from consumer products containing naturally occurring radioactive materials (NORM) is essential for source-term-based safety evaluation. This requires a sealed measurement chamber whose tightness and internal radon concentration homogeneity are characterized to ensure data integrity. We characterize a 0.343 m³ stainless-steel radon chamber housing two Durridge RAD7 alpha spectrometers for low-emanation NORM measurements. Chamber tightness, evaluated via the radon decay curve method over ~24 days, yielded a fitted leak rate constant statistically consistent with zero (1σ uncertainty 1.7 × 10⁻⁵ h⁻¹), more than an order of magnitude below the 5 % × λ_Rn acceptance criterion. To support spatial homogeneity evaluation, a MATLAB advection–diffusion solver with a real Navier–Stokes velocity field (Chorin projection method) was developed as a transferable computational framework, deliberately trading full turbulence-model fidelity for accessibility. Preliminary simulations indicate that fan-driven advection (2.0 m/s) reduces the spatial coefficient of variation (CV) below the 5 % target within ~10¹ arbitrary time units, approximately three orders of magnitude faster than under natural diffusion alone (~10⁴ a.u.). Experimental cross-validation using a calibrated Pylon ²²⁶Ra source and two RAD7 units in a crossover configuration is in progress and will be presented at the conference. This integrated experimental and computational protocol qualifies the chamber for high-precision radon exhalation measurements of NORM products, enabling consistent and conservative safety regulation.

Abstract

Cultural heritage preservation requires non-invasive in-situ detection techniques to avoid irreversible damage to fragile relics. Compton scattering imaging (CSI), based on single-sided backscattering detection, offers a promising alternative to X-ray transmission imaging for nondestructive testing (NDT) at archaeological sites. This paper presents two push-broom CSI systems for on-site in-situ NDT of cultural heritage. A modified 2D CSI system was deployed at an auxiliary pit in Xi’an, effectively revealing shallow subsurface burial features and locating unexcavated relics. A 3D Compton scattering tomography system was further developed to address depth limitations, featuring a soil penetration depth of over 10 cm and a spatial resolution of 1cm with preliminary experiments verifying its technical feasibility for 3D structural characterization of buried artifacts.

Abstract

The prompt detection of marine environmental radioactivity is essential in the wake of accidents such as the Fukushima event, yet conventional methods relying on bulk seawater sampling and offline analysis cannot provide timely information. We developed an in-situ underwater gamma-ray monitoring system, operable down to 300 m depth, that integrates real-time cesium preconcentration with a low-background gamma-ray spectrometer for deployment on unmanned surface vehicles, underwater gliders, and mooring platforms. The 18.54 kg system houses a seawater circulator, a pressure regulator, a dual-head gamma-ray detector, and a battery within a 58 cm × 21.4 cm watertight enclosure. Each detector head consists of a 2×2 tiled array of 48×48×20 mm³ monolithic GAGG:Ce crystals (96×96 mm² active area) coupled to a 16×16 SiPM array, with a KNiFC resin column placed between the opposing heads for selective ¹³⁷Cs adsorption. KNiFC-based preconcentration yielded over 92% ¹³⁷Cs recovery from spiked seawater. In a 30-bar pressure chamber, the system operated stably for 1 hour, and underwater background counts in the 662 keV region were reduced by a factor of 17 owing to water shielding. Under this low-background condition, two ¹³⁷Cs-preloaded adsorbent columns containing as low as 11.4 mBq and 73.2 mBq were observable within the 662 keV photopeak window, with net counts scaling consistently with the loaded activities. With a photopeak detection efficiency of 0.13, the system achieved a minimum detectable activity of 5.8 mBq/L for a 60 L sample within a 1-hour measurement, demonstrating sub-10 mBq/L sensitivity for in-situ ¹³⁷Cs detection in deep-sea environments.

Abstract

The variability of background radiation, primarily gamma rays and neutrons, can have a significant impact on the performance of detector systems. In nuclear security, background-limited minimal detectable activity constrains which sources can be detected with acceptable confidence. Furthermore, the radiation background can have direct impact on the false alarm rate; higher background levels can lead to increased false alarm rates, normally mitigated by increasing thresholds, which decreases the system sensitivity. The local environment is one of the main factors in background rate variation. Therefore, a vehicle-based system is a well-suited detector platform to investigate dynamically changing environments. This work summarises the design and creation of a custom vehicle-based system assembled at AWE-NST as a platform for experimental gamma and neutron background measurements. This platform can also be used to benchmark novel anomaly detection algorithms. This work details the results from the first measurement campaign taken in July 2025 with the system driven over 247 miles around the counties of Hampshire and Berkshire in the UK.

Abstract

The Korea Institute of Nuclear Nonproliferation and Control (KINAC) has developed a portable Monochromatic Micro X-Ray Fluorescence (MMXRF) analyzer. This device is designed for the on-site measurement and evaluation of safeguards environmental samples to rapidly identify and respond to undeclared nuclear activities. Due to its portable nature for field inspections, the equipment is frequently subject to transportation. This movement can lead to misalignments between critical components  which must remain precisely fixed for optimal performance. In this study, we conducted experiments to evaluate how transportation-induced alignment errors and environmental background noise affect the device's performance. The MMXRF system was transported from KINAC to two places. We measured the shift in the X-ray focal spot and background noise before and after each transit. Experimental results indicated a focal spot displacement of approximately 1.7 mm following transportation. While background noise levels remained relatively stable, significant performance degradation was observed during measurements of uranium-deposited swipe standard samples.  These findings suggest that the shift in the X-ray focal spot is a primary driver of performance loss. In conclusion, this study confirms that the alignment stability of the X-ray generator is a critical factor in maintaining the reliability of portable safeguards equipment. We will discuss detailed methodologies and technical solutions to mitigate these alignment issues at the conference to ensure the high-fidelity performance of portable MMXRF systems in the field.

Abstract

Cobalt-60 isotopes are sometimes detected in graphite blocks used in research reactors with small cores. One possible cause of this cobalt-60 is the activation of impurities within the graphite blocks by neutrons. Another possible cause is the activation of rust adhering to the surface of the graphite blocks. When disposing of these graphite blocks, the distribution of radioactive materials measured by non-destructive methods would greatly contribute to improving the accuracy of radioactive material quantification. Therefore, we prototyped simple gamma camera combining a pinhole collimator and a phosphor plate. Using this camera, we imaged the block from three directions and attempted to measure the three-dimensional distribution of radioactive materials based on the acquired data. We prepared the detector response function in advance through Monte Carlo simulation. Images were captured by the gamma camera experimentally with a PLA resin block embedded with a cobalt-60 source and estimated the position of the source using ML-EM algorithm. From these results, when the source was placed at the corner of the block, the location of the source was estimated in the correct position. On the other hand, when the source was placed at the center, it was estimated to be at an adjacent position. Improving the accuracy of the response function is the next step of this study.

Abstract

The Outer Space Treaty (OST), opened for signature in 1967 and ratified by 117 countries including the U.S., Russia, and China, prohibits the placement of nuclear weapons in outer space. The OST, however, lacks any verification mechanism, and no peer-reviewed methodology for verification has been proposed in the open literature. Recent concerns over Russia's Kosmos2553, suspected of testing nuclear-armed anti-satellite (ASAT) components, and a U.S. executive order calling for the detection of nuclear weapons in space, have made the need for a credible verification capability urgent. A nuclear detonation in Low Earth Orbit (LEO) could destroy most LEO satellites, as the 1962 Starfish Prime test demonstrated. This study presents a concept and feasibility analysis for verifying a satellite's compliance with the OST by detecting neutrons induced by proton spallation on the thermonuclear device's high-Z (uranium) radiation case. The interrogating GeV-energy protons are naturally provided by the inner Van Allen belt, requiring no active source. The proposed inspector is a 9U-CubeSat-sized directional neutron detector consisting of two 30x30 pixel planes, with each pixel formed by an EJ-276 PSD plastic scintillator wrapped in CVD-diamond active vetoes. Geant4 simulations characterize anti-coincidence rejection of the harsh proton/electron environment, directional discrimination of spallation neutrons from atmospheric albedo neutrons via neutron-scatter-camera kinematic reconstruction, and dead-time effects due to the high charged-particle flux. Combined with IRENE AP9/AE9 belt models and Carpenter's spallation yield, the analysis shows that the 9U inspector can confirm the presence of a thermonuclear weapon from a stand-off of 4 km in approximately one week, with a false-positive rate <1.1%. A constellation of ten inspectors at 1 km reduces this to a single-flyby inspection.

Abstract

This study investigated the quantitative effects of neutron camera configuration with various parameter—the number of channels, colimator window diameter, and channel allocation for each port—on imaging performance in Deuterium-Tritium (DT) fusion reactor environments. Plasma neutron emission profiles were generated using the TRIASSIC code, which generating plasma shape, and detector signals were calculated in both 2-D and MCNP-based 3-D environments. Neutron image reconstruction was performed using the calculated detector signals, and reconstruction accuracy was evaluated using the Normalized Mean Square Error (NMSE). First, neutron image reconstruction was performed using the reference neutron camera configuration proposed for ITER and EURO-DEMO, resulting in an NMSE of 3.12%. To improve reconstruction accuracy, an expanded neutron camera configuration consisting of 10 and 16 channels for each vertical and radial neutron camera(VNC and RNC) port, respectively, was applied. The reconstructed results yielded NMSE values of 1.59% in the 2-D and 1.85% in the 3-D environment, both lower than the reference value. Reconstruction accuracy was strongly affected not only by the total number of detector channels but also by the channel distribution and Line-of-Sight (LoS) coverage. In particular, asymmetric detector distributions in the VNC ports generally produced lower NMSE values than symmetric configurations, while increasing the detector channel number in the RNC port improved reconstruction accuracy overall. These results indicate that appropriate neutron camera configuration can enhance neutron imaging performance in DT fusion reactor environments and may provide fundamental data for future neutron camera design and optimization for DEMO-class fusion reactors.

Abstract

This study investigates the unique high-energy radiation environment of thunderstorms, focusing on terrestrial gamma-ray flashes (TGFs). Led by the Air Force Institute of Technology, the United States Air Force School of Aerospace Medicine, and the Air Force Research Laboratory, this effort deploys custom-built High Elevation Radiation Array (HERA) instruments aboard ten WC-130J “Hurricane Hunter” aircraft. These planes fly into hurricanes and tropical storms for the purpose of measuring weather data, potentially bringing them into proximity of TGF radiation. Each HERA unit contains a sodium iodide scintillator, a plastic scintillator, and associated data acquisition hardware. HERA represents the largest airborne campaign to date for near-source TGF observations and aims to improve understanding of TGF mechanisms, occurrence rates, and associated radiation risks to aircrew and equipment. All HERA detectors have been installed on aircraft and will collect data during the full 2026 Atlantic hurricane season.

Abstract

Floating-gate dosimeters (FGDOS) are being investigated at CERN as candidates for the next generation of Total Ionizing Dose monitoring devices in the accelerator complex. This work presents the characterization of floating-gate dosimeter structures through a standardized CERN BE-CEM-EPR radiation-test platform using a common carrier board, dedicated sensor daughterboards with standardized pinout, and a Pynq FPGA readout implementing reusable gateware libraries and continuous-integration firmware validation. The platform allows the same device under test to transition from laboratory bring-up to irradiation facilities without setup modifications. The sensor is fabricated in a 0.6 μm CMOS process and exploits a digital control component — handling structure selection, bias control, charge injection, and frequency readout — combined with analog floating-gate NMOS structures, each paired with a matched dummy reference transistor for differential read-out. Two structures with different floating-gate area to NMOS readout transistor ratios were characterized: a reduced-area variant at one quarter of the baseline retaining the same NMOS (TC994), and a variant with larger sensor area and optimized NMOS for lower noise (TC994). Four recharge modes were compared: disabled, comparator-based, counter-based, and bit-based. Temperature dependence of the sensor frequency was observed and used to validate the acquisition chain; sensor-to- reference frequency ratios were evaluated as a first-order thermal compensation method. The platform is being extended to a new generation of structures integrating normal NMOS, high-voltage NMOS, and parasitic NMOS readout implementations (TC994), whose laboratory and irradiation results will be presented with emphasis on suitability for future RadMon and BatMon Total Ionizing Dose monitoring at CERN.

Abstract

Accurate characterization of neutron fields is crucial in applications involving neutron-emitting radioisotopes, as surrounding materials can alter these energy distributions. This necessitates a detailed reconstruction of neutron flux distributions beyond just dose-rate measurements. Reliable neutron flux reconstruction using compact organic scintillation detectors remains challenging under spectrally modified neutron fields owing to nonlinear light yield and detector resolution effects. In this study, we investigated the robustness of neutron flux unfolding using a stilbene scintillation detector with response matrices optimized using a physics-informed genetic algorithm (GA) framework. Although local differences in the unfolded flux distributions were observed under source-or neutron field–mismatched conditions, the overall spectral shapes remained stable. The approach aids neutron flux reconstruction for various safety and evaluation applications. It enhances assessments in mixed radiation fields and nuclear environments.

Abstract

In recent years, increasing attention in nuclear and medical applications has focused on detectors capable of neutron–gamma discrimination, with Pulse Shape Discrimination (PSD) being one of the most widely used and versatile techniques. A compact real-time detector has been previously developed, providing an event-by-event digital PSD parameter and a flexible platform for both organic and inorganic scintillators, as demonstrated using the CLYC crystal and, more recently, the M-700 scintillator. The system is based on a scintillator coupled to NUV-HD SiPM arrays and compact front-end electronics enabling real-time acquisition and processing. The detector achieves moderate Figures of Merit (FOM) while ensuring reliable neutron–gamma separation. To investigate the factors limiting its performance, an analytical model of the full detection chain was developed, including scintillator–SiPM coupling, readout electronics, and the main noise contributions (electronic noise, statistical fluctuations, time jitter, amplitude walk, and finite bandwidth-induced shaping in the analog chain). This framework allows the decoupling and quantitative evaluation of the effects limiting discrimination accuracy. Preliminary results show good agreement with experimental data and identify the dominant limiting factors, providing guidance for targeted improvements and further performance enhancement.

Abstract

Accessing an early stage of damage evolution is a key factor for the aircraft industry. Positron annihilation allows very accurate and nondestructive measurement of defect density, and its future evolution, as probed by Doppler Broadening Spectroscopy. Once the limited availability of positrons is addressed using a nonradioactive positron generator, application of positron annihilation can be foreseen for maintenance activity addressing the aircraft industry.

The Blade Checker project is a proof of concept to demonstrate this capability. Although Blade Checker is focusing on the aircraft industry, this technique could be extended to other fields. It consists of a novel accelerator-based, radioisotope-free positron generator, custom HPGe detectors and an experimental setup allowing the defect density measurement on mechanical parts up to 3 dm³.

The AM Gen is an accelerator-based positron generator, developed by POSITHOT, with a compact design and including the Xray shielding. Complemented by a beam stretching device, it provides a continuous positron flux of approximately 5.10⁶ positrons per second. The generator has been commissioned by the French nuclear safety authority.

The signals coming from the positron annihilation require the resolving power of a High Purity Germanium (HPGe) detector focusing on the 511 keV peak shape analysis. MIRION Technologies developed a custom, 7-element, electrically cooled HPGe detector placed inside a vacuum chamber as close as possible to the sample to be measured. Several small elements are preferred over one large crystal to avoid pile-up effects. A time-listed multi-channel data-acquisition is used to have in-beam time correlation and coincidence.

A description of the systems, positron generator, HPGe system and readout, together with some results from material characterization and projected probing speed will be presented.

Abstract

Compensated neutron logging commonly employs isotopic neutron sources based on (α,n) reactions, such as Am–Be sources, which are typically approximated as point sources due to their small physical dimensions. However, alternative neutron sources based on (γ,n) reactions may require significantly larger target volumes to achieve sufficient neutron yield, making the point-source approximation no longer applicable. In this work, Monte Carlo simulations based on MCNP are performed to investigate the effect of neutron source length on compensated neutron logging response. A limestone–water formation model and a dual-detector configuration with near and far He-3 detectors are employed. The results show that the porosity sensitivity initially increases with source length, reaches a maximum at approximately 20 cm, and then gradually decreases. A figure-of-merit (FOM) combining sensitivity and statistical stability is further introduced, which increases monotonically with source length while gradually approaching saturation. The results provide a quantitative basis for neutron source optimization in compensated neutron logging.

Abstract

Compton cameras (CCs) have a large field of view and a wide energy detection range, and are useful in nuclear security monitoring, environmental radiation measurement, nuclear accident response, and radiation source localization. However, their depth accuracy is still limited in practical three-dimensional source localization. A single detector view provides weak spatial constraints, so traditional Compton reconstruction methods can produce depth errors, especially with few events, strong noise, or distant sources. Artifacts may also appear in the reconstructed images. To address this problem, we propose a three-dimensional radiation source reconstruction method for a compound-eye Compton camera based on a NeRF neural network structure. The aim is to improve localization accuracy by combining the compound-eye geometry with neural field learning. We simulated a compound-eye detector system with 25 scatterers arranged on a spherical surface and absorbers arranged in a plane. For each detector view, list-mode Compton event data were used to perform independent MLEM reconstruction, and a source distribution image was obtained. These reconstructed images and the corresponding detector pose information were then used as training data for the neural field network. Preliminary results show that, after training with multi-detector data, the reconstructed three-dimensional radiation intensity distribution becomes more concentrated. The peak intensity position is closer to the true source position, and the depth shift is reduced. These results show that multi-detector geometric constraints can provide useful information for three-dimensional radiation source reconstruction, and that combining a compound-eye Compton camera with neural field reconstruction is feasible.

Abstract

The European Spallation Source (ESS), expected to start its scientific program in 2027, will be the world's most powerful neutron source. This facility requires advanced systems for accurate beam monitoring and diagnostics. To meet these requirements, dedicated detectors have been designed to operate at ESS, one of them being the Ionization chamber Beam Monitor (I-BM). This work presents detailed simulation studies, using Geant4, Garfield++ and LTspice, to investigate energy deposition, charge transport, induced current  formation, and front-end electronics response. Experimental data from neutron beam test campaigns are also included to support the evaluation of the I-BM performance.

Abstract

Fast, spatially complete and digitally usable radiation information is essential for radiation protection in nuclear power plants (NPPs), particularly during maintenance, decommissioning and emergency response. Conventional surveys usually separate geometric measurement from dose-rate measurement, which makes data acquisition slow, labor-intensive and difficult to integrate with digital radiation-protection platforms. This paper presents an indoor three-dimensional (3D) gamma radiation mapping method based on visual simultaneous localization and mapping (VSLAM). The developed DoseMap system combines an RGB-D VSLAM module with a hot-pluggable Geiger--Muller gamma dose-rate detector. Environmental point clouds, measurement trajectories and gamma dose-rate data are fused through timestamp synchronization and an integral path midpoint method, enabling real-time 3D visualization, radiation-field interpolation and hotspot localization. Tests in laboratories and NPP environments show that more than 80\% of the reconstructed scene point cloud is within 0.2 m of the reference cloud, the trajectory localization error is approximately 4 cm, the single-source hotspot localization error is less than 0.2 m, and measurement efficiency is improved by a factor of 26.8 compared with traditional survey workflows. The method has also been linked with the smart radiation-protection support system(SMARP), demonstrating its potential for digital twins, ALARA planning and remote or robotic radiation surveys.

Abstract

Illicit transport of uranium-bearing materials remains a concern for nuclear security when passive radiation signatures are weak, shielded, or ambiguous. Active photon interrogation can induce photofission in uranium using a Bremsstrahlung field generated by 9 MeV electrons and provide neutron signatures from this reaction. Established photofission approaches commonly exploit delayed neutrons or delayed gamma rays measured after irradiation or in beam-off windows, which helps reject prompt radiation fields but imposes constraints on timing, sufficient decay statistics, and acquisition duration. Here, we propose a proof-of-concept measurement of prompt photofission neutrons using a depleted uranium bar and a commercial superheated droplet detector. Such passive neutron sensors rely on nuclear recoils that form bubbles when local energy deposition exceeds a thermodynamic threshold, while photon-induced low-LET interactions are strongly suppressed. Although superheated droplet detectors are established for neutron dosimetry and photon rejection, their use for measuring prompt neutrons from photofission during active photon interrogation has not, to our knowledge, been demonstrated experimentally. Measurements will be acquired with and without uranium under identical beam, geometry, shielding, and temperature conditions. The integrated response will be normalized to irradiation time under fixed beam settings, with beam-current or dose-monitor information used to check the stability of the photon output. A 20°C temperature-controlled bath stabilizes detector response. Polyethylene shielding is placed within the direct solid angle of the converter as seen by the detector, in order to reduce the linac-induced photoneutron component reaching the measurement region. The experiment will test whether uranium produces a reproducible excess above this background and will define requirements for prompt photofission neutron measurements at sub-10 MeV electron energy.

Abstract

Portable gamma-ray spectrometers with integrated imaging capability represent a significant advancement in field radiation detection by combining radionuclide identification with real-time source localization. These systems have the potential to reduce operator dose through stand-off detection while improving situational awareness in safeguards, emergency response, and radiological assessment missions. This work characterizes and compares two novel handheld gamma-imaging spectrometers: the PHDS GeGI, a mechanically cooled high-purity germanium (HPGe) system, and the H3D H420, a cadmium zinc telluride (CZT)-based detector employing room-temperature semiconductor technology.  Baseline performance testing evaluated energy resolution, intrinsic photopeak efficiency, imaging capability, and operational factors including power consumption. Laboratory measurements confirmed that both detectors achieved manufacturer-stated energy resolution at 662 keV, with the GeGI demonstrating superior spectroscopic resolution while the H420 exhibited greater intrinsic photopeak efficiency across much of the tested energy range due to detector geometry and material characteristics. High-gamma-flux testing revealed that the H420 maintained functional spectroscopy and reliable gamma-imaging performance at significantly closer source distances, whereas the GeGI experienced degradation in spectral quality, imaging accuracy, and mission suitability under elevated exposure conditions.  The results demonstrate complementary advantages between the two systems: the GeGI provides superior high-resolution isotope identification, while the H420 offers improved operational robustness, imaging stability, and field deployability. These findings support the development of expanded field-performance evaluation frameworks for next-generation gamma-imaging spectrometers and provide guidance for mission-specific detector selection.

Abstract

R3B is a fixed target experiment at the Facility for Antiproton and Ion Research (FAIR) (DE). The setup comprises different sub-detectors that perform kinematically complete measurements of reactions with high-energy radioactive beams. One such sub-detector is the Target Recoil Tracker (TRT), placed in vacuum around a target. The TRT aims to detect light charged particles with an efficiency of ≥ 65 % and provide precise tracking (≤ 10 μm), angular resolution (≲ 2 mrad), and reaction vertex reconstruction, over a large acceptance (≈10° to 90°). It consists of two concentric barrels with radii 5 cm and 6.5 cm, and a total active length of ∼ 27 cm. It utilizes silicon Monolithic Active Pixel Sensors (MAPS) thinned down to 50 μm. The ALPIDE sensor, developed by ALICE/CERN, was chosen as its technology is mature and fulfills the R3B detector requirements.

A module consists of 9 chips glued to an aluminum-based Flexible Printed Circuit (FPC) and wire-bonded, with a total material budget of ∼ 0.16% X/X₀. The assembly has undergone extensive prototyping through low-, mid-, and high-readiness modules, during which assembly procedures, quality assurance, databases, manuals, and electrical tests were developed in preparation for launching pre-production. The last batch of high-readiness prototypes has been assembled with all final materials and tested. The prototypes show a functional response from all chips, demonstrating the ability to construct fully working production-level modules. Validation tests include a scan of the module with a ⁹⁰Sr source coupled to an external trigger, and vacuum tests down to 1×10⁻⁴ mbar. This paper will present the latest developments from the last prototyping stage. UKRI-STFC Laboratories and the University of York aim to deliver 60 production-level modules to FAIR by October 2027.

Abstract

The Compton camera has emerged as a pivotal gamma-ray imaging technique, with critical applications in astrophysical observation, nuclear safety monitoring, and environmental radiation detection. In nuclear astrophysics, the detection and localization of gamma rays in the MeV range are indispensable for probing high-energy cosmic phenomena. Despite its importance, the advancement of MeV gamma-ray imaging instrumentation remains constrained by low interaction probabilities and high imaging complexity. This study presents a single-layer Compton camera prototype designed for enhanced spatial imaging, building upon the mission heritage of the BNU-120—a space-borne detector successfully deployed for monitoring gamma-ray bursts (GRBs). To transcend the original system's lack of spatial imaging capability, we propose a high-performance architecture that leverages the established BNU-120 framework while integrating a dual-ended readout to achieve a 4π detection solid angle. The prototype uses a 8×8 Ce:GAGG array coupled to Hamamatsu Multi-Pixel Photon Counters (MPPC, S14161-3050HS-08) at both ends. Each crystal measures 3×3×25 mm³ and is optically isolated by 0.2-mm-thick BaSO₄ reflective layers. System characterization demonstrated an energy resolution of approximately 5% (FWHM) at 511 keV. Depth-of-interaction (DOI) information, extracted via the energy ratio method, yielded a DOI resolution of roughly 2 mm (FWHM) along the crystal axis. Computational validation using GATE simulations of a U-shaped 511 keV planar source showed that the source geometry was clearly distinguishable through a back-projection (BP) algorithm. Subsequent point-source experiments verified the detector's capability to localize discrete sources. Future work will focus on realistic physical imaging experiments and the exploration of more advanced reconstruction algorithms to fully evaluate the module's Compton imaging performance.

Abstract

A 1U-CubeSat payload for the Gamma-Ray Integrated Detectors (GRID) mission has been developed, expanding its scientific scope from transient gamma-ray burst (GRB) monitoring to include space-based neutron lifetime measurements in Low Earth Orbit (LEO). Constrained by a strict form factor (1U, 1.3 kg, 8 W), the payload retains two legacy GAGG scintillators for GRB detection while introducing two novel CLYC-plastic phoswich probes for thermal neutron measurement. To discriminate thermal neutrons within complex orbital backgrounds, the phoswich architecture enables robust pulse shape discrimination (PSD). To mitigate spacecraft-induced secondary neutrons, Gadolinium (Gd) shielding is applied to the sides and backs of both phoswich probes. Furthermore, a differential front-shielding design is employed to extract the thermal neutron flux. An in-orbit Charge Comparison Method (CCM) algorithm is implemented, which optimizes telemetry by processing the PSD signals in real-time, adding only two bytes per event. Ground calibrations demonstrate a neutron-gamma Figure of Merit (FoM) of 1.25, and preliminary cold neutron beam tests validate the differential shielding concept. The payload successfully balances multi-messenger astronomy and fundamental physics goals, verifying its readiness for flight.

Abstract

The ATLASPix3.1 is a full reticle HV-CMOS sensor [1]. It is under study for future lepton colliders [2] and is part of the family of sensors leading to the MightyPix for LHCb and the MuPix for Mu3e. This makes detailed studies of the sensor performance important. We previously reported signal to noise, cluster size and position resolution [3]. Here a detailed study of cross talk and charge collection is presented. Between ATLASPix3.0 and ATLASPix3.1 masks were changed to improve the chip properties at the cost of introducing cross talk. Two types of cross talk were found. Type I yields small signal at fixed positions determined by the hit location. These typically have a signal less than 15% of the original signal. Around 99% of these clusters can be suppressed using a simple minimal signal cut. There is a second type of cross talk hits that yield high signals. An attempt was made to identify these cross talk hits using a gradient-boosted decision tree analysis with variables reflecting cluster shape & signal and signal spread over the pixels. We show that it is not possible to efficiently remove these hits based on cluster properties. This can result in a track candidates with similar χ². This can be addressed in an updated design of the sensor and/or by further optimising settings. Using a grazing angle scan the charge collection was studied. In the depletion zone, the charge will be collected quickly. Charge generated in the non-depleted zone will yield a lower and later signal. The depth of the depletion zone was derived as a function of bias voltage. The results show that the depletion depth is proportional to the square root of the bias volrage as would be expected for a planar silicon detector. The experiments have shown that the sensor has very good performance, serving as a promising candidate for future lepton colliders.

Abstract

The ALICE ITS3 upgrade represents a major advancement in silicon tracking, exploiting the commercial 65 nm CMOS imaging technology to develop ultra-thin monolithic active pixel sensors (MAPS) for high-energy physics applications. The target detector performance includes an extremely low material budget below 0.09% X0 per layer, with a spatial resolution below 5 μm, and radiation tolerance up to 4×10¹² 1 MeV n_eq cm⁻².
Several pixel test structures have been designed and fabricated to investigate both sensor geometries and front-end architectures. In particular, analogue pixel test structures (APTS) featuring a fast operational amplifier (APTS-OA) as output buffer have been developed to study charge collection dynamics and the intrinsic timing performance of the sensor. Measurements performed in charged-
particle beam tests demonstrated a best time resolution of 63 ps, combined with a charge collection efficiency above 99% and a spatial resolution better than 3 μm, while maintaining stable performance up to 1×10¹⁴ 1 MeV n_eq cm⁻².
Building on these results, a second engineering run (ER2) introduced three novel chip variants targeting enhanced detector performance and improved radiation robustness. In particular, the optimization of the low-dose n-implant located below the n-well collection electrode aims at reducing the sensor capacitance while enhancing the lateral electric field, thereby improving sensor
depletion and restoring charge collection performance after radiation damage.
This contribution presents the characterization of the new APTS-OA variants and discusses their impact on timing performance, charge collection efficiency, and radiation tolerance through measurements performed on both irradiated and non-irradiated devices.
Laboratory characterization results will be presented providing insight into the effectiveness of the ER2 design optimizations for radiation-tolerant fast MAPS detectors.

Abstract

The ATLAS Liquid Argon (LAr) calorimeter readout electronics are being upgraded for operation at the High-Luminosity Large Hadron Collider (HL-LHC), where up to approximately 200 proton-proton interactions per bunch crossing will significantly increase detector occupancy, data throughput, and trigger rates. While the calorimeter detectors themselves remain unchanged, the full readout electronics chain is being replaced. The upgraded off-detector processing system continuously receives digitized calorimeter signals from approximately 182000 channels at the 40 MHz bunch-crossing rate through high-speed optical links. The processing architecture is implemented in Advanced Telecommunications Computing Architecture (ATCA) systems hosting large FPGAs performing real-time reconstruction of energy and timing while satisfying stringent trigger latency requirements. Prototype hardware and firmware have been developed and validated in integration setups combining front-end electronics, timing distribution, and data acquisition systems. In parallel, advanced reconstruction methods including machine-learning approaches optimized for FPGA implementation are being investigated to improve robustness against pileup and overlapping pulses.

Abstract

Precision physics at future e+e− Higgs factories set stringent requirements on calorimetric performance, with 3%/√E for electromagnetic particles and ∼ 30%/√E for neutral hadrons identified as key benchmarks. A hybrid dual-readout approach, combining a homogeneous crystal electromagnetic section with a fiber-based hadronic section, offers a cost-effective path toward simultaneously achieving both targets. Reaching such performance requires enhancing the longitudinal and transverse granularity of the crystal section beyond what is available in conventional homogeneous calorimeters and equipping each crystal cell with two independent readout channels to simultaneously collect Cherenkov and scintillation light. These features enable advanced particle-flow dual-readout reconstruction algorithms to exploit the maximum available information from each event. This work will present extensive laboratory characterizations together with beam-test measurements carried out at CERN on single-crystal PWO, BGO, and BSO cells instrumented with optical filters and SiPMs. These studies demonstrate event-by-event separation of Cherenkov and scintillation light, with both scintillation and Cherenkov yields exceeding the thresholds required for optimal electromagnetic and hadronic energy resolution. The results have guided the technological choices for the ongoing construction of full-containment calorimeter prototypes

Abstract

An upgrade of the LHCb electromagnetic calorimeter (ECAL) is planned for Long Shutdown 3
(LS3) to address significant aging effects in the central region caused by radiation damage and
high particle flux. The innermost ECAL modules will be replaced with a new design based on
Spaghetti Calorimeter (SpaCal) technology, optimized for radiation tolerance and improved
performance under high occupancy conditions. A total
of 176 SpaCal modules will be installed. These are based on scintillating plastic fibers embedded
in dense absorbers. The innermost 32 modules will use 3D-printed tungsten absorbers to
withstand the highest radiation levels, while the remaining 144 modules will employ lead
absorbers produced through an innovative casting technique. Both configurations have been
prototyped and extensively validated in test beam campaigns at
DESY-II and CERN SPS. The measured energy resolution for electron beams is consistent with
performance requirements and shows good agreement with detailed Monte Carlo simulations. The
scintillating fibers will be read out using radiation-hard hollow light guides coupled to fast photon
detectors. In total, 3072 new readout channels will be implemented with dedicated front-end
electronics. In parallel with the installation of the new SpaCal modules, the current Shashlik
calorimeter modules will be rearranged to better match the spatial distribution of particle
occupancy. Simulation studies demonstrate a significant reduction in per-cell occupancy after the
LS3 upgrade, improving detector performance in Run 4 conditions. Benchmark analyses of key
physics channels confirm that this enhancement leads to a substantial gain in reconstruction
efficiency and measurement precision. Overall, the LS3 ECAL upgrade represents a crucial step
toward coping with higher luminosity conditions and anticipates key design features of the future
PicoCal system foreseen for implementation during LS4.

Abstract

ePIC is the general purpose detector for the Electron-Ion Collider (EIC)
that is being built at Brookhaven National Laboratory and will be ready for first physics 
when the Electron-Ion Collider turns on.  ePIC is based
on a new 1.7T superconducting solenoid magnet.  The detector
consists of precision tracking, particle identification and 
calorimeter (electromagnetic and hadronic) to measure the
properties of electron-Ion collisions that will occur at the
EIC. In this paper we will present the over all design of the ePIC
detector, with a focus  on the Barrel Hadronic Calorimeter (BHCal)
which is the repurposed sPHENIX Outer Hadronic Calorimeter (HCal).
We will also present the current status of the BHCal design, test stand
and preliminary results of the new electronics readout system based on the 
CaloROC chip designed for ePIC

Abstract

The ATLAS Experiment is preparing for the Phase 2 upgrade. Leading the upgrade program is the replacement of the current Inner Detector with an all-silicon Inner Tracker (ITk) designed to operate during High-Luminosity LHC with an average of 200 proton-proton interactions per bunch crossing. The ITk will consist of a Strip detector and a Pixel detector. The five layer Pixel detector will be constructed from three sub-systems. One system occupying the central three outermost layers, called the ITk Pixel Outer Barrel, will use carbon-fiber local supports with steel pipes that provide CO2 cooling and services for 4472 loaded pixel detector module cells. A loaded module cell combines an ITk pixel hybrid module with four front-end chips and a thermo-mechanical structure called bare cell. The bare cell is made of aluminium graphite block and pyrolithic graphite tile for precise positioning and thermal coupling respectively. 
The contribution will share experiences from the pre-production qualification campaign for loaded module cell assembly and quality assurance carried out last year. The institutes loaded onto bare cells and thoroughly characterized about 134 modules to verify the production procedures, loading accuracy, electrical integrity, and thermal performance at each site. The pre-production campaign demonstrated reliable assembly and testing capabilities in a large-scale production chain, and it identified an insulation issue between the module and the bare cell, allowing corrective actions before large-scale production.
This contribution presents the developed site production equipment, the homogenization process of the equipment, and common production rules between sites. The entire cell loading workflow and qualification procedures will be explained, as well as the results, and systematic studies of the pre-production run will be shared. Ultimately, the contribution will show lessons learned to produce components for the best possible tracking detector.

Abstract

In the framework of the ARCADIA collaboration several INFN groups developed a Monolithic Active Pixel Sensor realized in 110 nm CMOS technology capable to operate with fully depleted substrate. Several prototypes embedding different substrate thickness have been produced and tested. In this contribution we detail the design and operation of the first multilayer particle tracking telescope realized with such technology, and successfully tested at the DESY II Test Beam Facility.
The telescope uses 6 tracking planes, each realized with an ARCADIA sensor, and is paired to a 7th layer, the device under test, which was also an ARCADIA sensor, only with a different substrate thickness. The tracking apparatus includes a scintillator based triggering system, a complete synchronization electronics, and a parallel DAQ system for control and data readout.
Together with a brief description of the sensor, the whole telescope system is depicted, detailing the relevant design choices and the expected performances. Maximum rates, resolution and other key metrics are derived from the telescope technical characteristics, and bench-marked against test-beam results. Measured performance are also compared with respect to the gold-standard MIMOSA telescope available at the same test-beam facility, which was used to characterize the same Device Under Test for reference.
A discussion about the strength and weaknesses of the technology, as well as the foreseen improvements and potential applications will close the discussion. Also, potential area of application, both in physics research and in applied fields will be highlighted.

Abstract

This work reports on the experimental characterization, modeling and correction of high intensity effects on the pixel response of the DEPFET Sensor with Signal Compression (DSSC) camera, an active pixel detector targeted at soft X-ray imaging experiments at the European XFEL. Experimental tests with up to 5 MeV/pixel deposited energy have been performed at the European XFEL, showing evidence of a shift of the pedestal value growing with X-ray intensity. Moreover, the signal compression provided by the DEPFET (DEpleted P-type Field Effect Transistor), integrated in each pixel, enhances the impact of this systematic effect on the measurement accuracy. The observed shift is assumed to be proportional to the signal dependent drop of the power supply lines along each ASIC column and can be modeled by two parameters. We devised a procedure to efficiently measure the two model parameters by means of a custom mask that shields a fraction of each ASIC column, irradiated with a flat field. The main results of the characterization of the signal dependent pedestal shift parameters and the application of the resulting correction to X-ray images of different patterned masks (dots, stripes, 2D shapes etc.) acquired at increasing intensities will be presented and discussed.

Abstract

We present the XSTREAM Pathfinder, an exploratory R&D effort at the European XFEL aimed at defining detector technologies for a potential facility upgrade. The activity addresses a broad photon-energy range, from soft X-rays starting at about 250 eV to hard X-rays up to 50 keV, and is structured around three main building blocks: sensor and interconnection technologies, prototype readout ASICs, and a first-stage DAQ system at camera level. The goal is to investigate detector concepts combining pixel sizes of about 100 µm, MHz-rate capability, and flexibility with respect to possible future XFEL timing structures. Baseline sensor options include silicon diodes and MiniSDDs for soft X-rays, and (thick) silicon diodes for hard X-rays in the 9–12 keV range, with high-Z materials (e.g. CdTe, CZT) considered for extending the operation toward higher photon energies. More advanced options for soft X-rays, including DEPFETs and LGADs, are also under investigation. On the ASIC side, prototype developments will be implemented in scaled CMOS technologies (28 nm or 22 nm), aiming at maximizing the reuse of both analog and digital building blocks across different sensor implementations. While sensor-specific front-end adaptations are required, a common architecture is pursued for key elements such as analog filtering, predictive gain switching, in-pixel digitization, and high-speed data serialization. A central challenge is the development of a high-throughput readout enabling continuous operation at up to 1 MHz, opening the path toward CW or high-duty-cycle modes, while maintaining backward compatibility with burst-mode operation. The Pathfinder will progressively validate the readout chain from sensor to digital output, including early studies of DAQ-level real-time data reduction.

Abstract

The Data Acquisition (DAQ) system of the DEPFET Sensor with Signal Compression (DSSC) megapixel (Mpx) camera at the European X-ray Free-Electron Laser (EuXFEL) is being revisited to support higher-performance detectors. The current digital front-end consists of two Field-Prgrammable Gate Array (FPGA)-based stages: the Input Output Board (IOB), responsible for initial data acquisition from Application Specific Integrated Circuits (ASICs), and the Patch Panel Transceiver (PPT), which manages data reordering and remote control. In the present 1-Mpx configuration with 9-bit pixel resolution, each IOB serves 16 ASICs (0.29 Gbps), four IOBs form a quadrant (18.88 Gbps), and four PPTs handle the full camera (75.49 Gbps). Since the AISCs and IOBs operate inside a vacuum enclosure at about −20 °C, any upgrade must comply with strict constraints on size, power delivery, and thermal management. In this context, EuXFEL is exploring both near- and long-term upgrade paths driven by the evolution of DSSC toward a 4-Mpx detector with 10-bit pixel resolution and higher throughput. The current system stores about 8,000 frames per second out of the 27,000 pulses per second produced by EuXFEL; near-term targets are 10,000 fps and 27,000 fps, while the long-term goal is continuous operation up to 1 Mfps. These modes would increase the required data transfer rate by factors ranging from about 5.55 to 15 in the near-term, and up to 555 in the long-term scenario, highlighting the main limitation of the current IOB. The IOB must be redesigned with a more powerful FPGA to meet near-term targets while enabling advanced data processing for long-term scenarios (e.g., lossless compression). The current capacitor bank—a simple power approach for DEPFETs—is therefore reconsidered; its removal frees up to about 50% of the IOB area, allowing the integration of additional memory and paving the way toward significantly higher data rates.

Abstract

The increasing brilliance of fourth-generation synchrotron sources drives a growing demand for energy-dispersive X-ray fluorescence (XRF) spectrometers capable of handling extreme photon fluxes.
We present the design and characterization of the ARDESIA-64 instrument, a complete X-ray fluorescence (XRF) spectrometer for high-throughput synchrotron applications. 
The instrument integrates a highly scaled 64-channel monolithic Silicon Drift Detector (SDD) array, featuring a pixel pitch of 2.5 mm, within a compact, vacuum-compatible mechanical housing tailored for beamline integration.
At the conference, we will present the instrument design and comprehensive spectroscopic characterization results. 
The collimated 450 μm-thick sensor variant demonstrates an excellent average energy resolution of 125.9 eV FWHM at 5.9 keV. Preliminary high-rate tests confirm exceptional throughput capabilities, sustaining Input Count Rates (ICR) exceeding 800 kcps per channel while preserving an energy resolution of ~150 eV. The readout is performed by a 64-channel Digital Pulse Processor (DPP) based on the CAEN DT5560SE digitizer with firmware specifically adapted for high-throughput X-ray spectroscopy in synchrotrons.

Abstract

Conducting isotopic level material control and accountancy of radioactive materials in fluids is challenging for multiple reasons: optical and electronic methods only provide elemental information, gamma-based methods face difficulties quantifying total concentrations, and destructive mass spectroscopy is costly and time consuming. Alpha-based techniques are typically not feasible due to the particles short (10-20 μm) range in dense matter and often require radiochemical separations in conjunction with electroplating. In this presentation we will present a novel sensor design that utilizes microfluidic structures which constrain the sample to a thin volume, limiting the energy loss of alpha particles, enabling spectroscopic measurements. If the alpha-particle energy is properly conserved it will allow for identification of the isotopes present, while the known sample volume will provide a means of calculating the isotope mass and subsequent concentration.

Abstract

The rhizosphere is the zone surrounding plant roots where there is mutual influence exerted between soil microbes and the roots. In this zone biological and chemical activity is driven by compounds exuded by or present in the root and consumed by specialized types of fungi and bacteria that inhabit or surround the roots. Understanding the dynamics occurring in the rhizosphere regarding plant-microbe, plant-plant and microbe-microbe interaction is the focus of much plant ecophysiology research. Plant biologists often use radioisotopes of carbon, iron, phosphorous and calcium to study this plant-microbe interaction but their radioisotope imaging methods are static and destructive. The Beta Rhizotron is a beta (b)particle imaging detector designed for dynamic, non-invasive, in-vivo/in-situ imaging of plant roots being studied using b-particle emitting radioisotope tracers. Potential tracers include ¹⁴C, ³²P, ⁴⁵Ca and ⁶⁴Cu via detection of their emitted b-particles from roots grown in a special container called a rhizotron/rhizobox. The detector is a gas based charged particle detector known as a micro-pattern gaseous detector (MPGD). Large area MPGDs are used in particle physics research. The use of a MPGD coupled to a rhizobox for low energy b-particle detection requires an MPGD able to operate in a varying temperature and humidity environment of standard growth chambers to obtain dynamic images of the bio-distribution of b-particle emitting radioisotopes. A key optimization of MPGD construction we are reporting here is the choice of window material.To estimate the expected 2-D intensity histograms simulations were performed using GEANT4 for ⁶⁴Cu with the b+ endpoint energy of ~0.65 MeV.Simulated was an 8 µm Kapton window, a 6 µm aluminized Mylar MPGD cathode/window, a 3 mm thick MPGD drift gas volume and a 1 x 1 x 70 mm³ water column with a uniform spatial distribution of the β-particle emitter to approximate a root. Results indicated adequate imaging results.

Abstract

This project advances a self-contained, portable True Random Number Generator (TRNG) grounded in the quantum-physical randomness of radioactive decay, integrated with an AI-driven monitoring and adaptive control system, for post-quantum cryptography (PQC) in mission-critical environments where remote connectivity is unavailable or constitutes an unacceptable security risk. Conventional cryptographic methods are projected to be vulnerable to quantum computing attacks by 2030, and NIST has mandated migration to PQC standards (FIPS 203–205) by 2030–2035. A fundamental requirement of PQC is a hardware TRNG capable of producing certified entropy without software-based pseudo-randomness. Existing solutions, e.g., cloud-connected beacons, large optical facilities, are incompatible with the remote, radiation-exposed, and network-denied settings of nuclear power plants, satellites, submarines, and forward military installations. Silicon SoC (system on a chip)-based TRNGs further fail in these environments, as ionizing radiation effects (total ionizing dose, single event upsets, direct damage) can bias, degrade, or manipulate their entropy output. Radioactive decay is a quantum-physical process that is intrinsically random, radiation-environment-tolerant, and scalable to NRC-exempt activity levels, making it ideally suited to this application.

Abstract

Cryogenic microcalorimeters are low-noise thermal detectors that have demonstrated gamma-ray resolution better than 100 eV at 100 keV, resolving lines unresolvable by conventional spectrometers. Achieving this resolution with an array of transition-edge sensors (TESs), however, requires that all TESs, each with a slightly different transition temperature, be simultaneously biased near their individual operating points. Because the TESs on a given readout line share a common bias, ensemble performance is determined by global parameters: the mixing-chamber temperature, the TES bias current, and the readout electronics configuration. A parametric study was performed to identify the operating point that maximizes the number of usefully contributing pixels and the combined energy resolution. Results of this study will be discussed, along with the methodology for combining and analyzing spectra across the array.

Abstract

QD nanostructures have emerged as highly versatile materials for sensing ionizing radiation. However, comparatively little is known about how QDs respond to non-ionizing radiation such as fast and thermal neutrons, where neutron capture, rather than ionization, is the dominant interaction mechanism. This study examines the viability of graphene QDs as neutron dosimeters or neutron–gamma discriminators. Additionally, research into QDs can aid in nuclear non-proliferation and dosimetry. The goal of this research is to investigate the effects of neutron irradiation on the optical properties of graphene QDs for non-proliferation applications. The results of this work provide insight into the mechanisms through which neutrons alter QD electronic structure and optical response. This study will contribute to the broader effort to develop hybrid or stand‑alone QD‑based radiation sensors and markers capable of operating across diverse radiation environments and even being incorporated into fuel.

Abstract

Transition-edge Edge Sensor (TES) microcalorimeters (TES) are attractive promising detectors for gamma-ray spectroscopy because of their excellent energy resolution[1]. However, TES detectors microcalorimeters generally have small sensitive effective areas, and large-scale arrays are required to achieve high detection efficiency. Since TESs operate at cryogenic temperatures, increasing the number of TESs increases Joule heating and readout complexity.

To address this issue, a Position-Sensitive TES (PoST) structure microcalorimeters haves been proposed to realize a large effective detection area with a small number of TESs. The Our gamma-ray PoST consists of a long lead absorber with TESs attached to both ends, and the incident position of gamma rays is estimated from differences in pulse shapes.

In this study, we evaluated the energy resolution and position resolution of the PoST detector by simulations considering thermal intrinsic noise and gamma-ray multiple scatteringinteractions. The simulations were performed using a finite element model coupling thermal conduction and TES electrical circuits. Sub-millimeter position resolution was achieved for 1333 keV1.33 MeV gamma rays.

Abstract

Optical-fiber dosimetry, based on Radiation-Induced Attenuation (RIA) or Radiation-Induced Luminescence (RIL), has progressed from particle-accelerator research to space applications. The first space-borne implementation, the LUMINA experiment, flew on the International Space Station during the ALPHA mission. LUMINA used several kilometres of specially selected silica fiber to provide dose-rate-independent, temperature-independent, and particle-type-independent measurements, successfully monitoring the ISS radiation environment, including each passage through the South Atlantic Anomaly.

To meet the more demanding radiation levels, mass, volume, and power constraints of CubeSat missions, we have miniaturized the LUMINA architecture into GlowRIA. In this new design, the fiber length was reduced to a few hundred metres and can be adjusted according to the expected mission dose. The optoelectronics, including the laser and photodiodes, were selected for lower power consumption and a more compact form factor. In addition, the read-out electronics were replaced by a radiation-tolerant microcontroller, eliminating the Raspberry-Pi board used on LUMINA and ensuring resilience to both cumulative dose effects and single-event effects.

GlowRIA has been subjected to a comprehensive qualification campaign reproducing harsh orbital conditions such as vacuum, large temperature excursions, electromagnetic interference, and total ionizing dose. The tests confirm that the dosimeter retains its performance while meeting CubeSat power and mass budgets.

We are also conducting Total Ionizing Dose calibration of the instrument using a Co-60 source, while Single Event Effects testing is planned at a later stage. The results of the environmental, radiation, and performance qualification campaigns will be presented in the full article.

Abstract

Large volumes of liquid argon or xenon serve as highly effective media for detecting neutrino interactions and searching for dark matter. Conventional noble-liquid detectors typically use scintillation light for timing or calorimetric measurements only, while relying on charge drift in a time projection chamber for spatial reconstruction. 
Direct optical reconstruction of events by imaging scintillation light could provide an alternative to the slow charge collection, also eliminating the necessity for an electric drift field. The increased rate capability enables new applications, including detectors at high-intensity neutrino beams and medical imaging (whole-body PET). 
Thanks to finely segmented Silicon PhotoMultiplier arrays and appropriate optical systems, it is feasible to create cameras capable of ``photographing" the primary scintillation light. A significant challenge is presented by the fact that both argon and xenon emit scintillation light in the vacuum-ultraviolet spectrum. To overcome this, coded aperture masks are employed instead of conventional lenses, enabling the construction of thin cameras with wide and deep fields of view. A reconstruction algorithm based on Maximum Likelihood Expectation Maximization has been developed to generate a 3D map of energy deposition. The most recent results from simulations and reconstructions of particles tracks in a liquid argon detector equipped with these cameras will be discussed.

Abstract

Since their invention in the 1970s, high purity germanium (HPGe) detectors have been the gold standard for the detection and spectroscopy of gamma rays. Developments in the fabrication, packaging, and operation of HPGe detectors, as well as in readout electronics and signal processing, have led to their application in fields as diverse as fundamental nuclear and particle physics, nuclear security and safety, and nuclear medicine. Based on decades of experience in electrical cooling technology, in recent years Mirion Technologies has developed rugged germanium detectors that can be used in difficult conditions traditionally considered too challenging for HPGe detectors. An example of such a detector is our newest product: the MicroGe detector. Due to it is small form factor and rapid deployment capability, the MicroGe detector can be used in medical radioisotope production facilities where high resolution is critical to identify impurities in samples. The MicroGe detector is capable of going from storage to measurement in less than 30 minutes which is a revolutionary achievement for HPGes. This paper presents results of the evaluation of a novel ultra-compact electrically cooled germanium detector as a quality-control instrument for quantification of for radionuclide impurity of samples.