Online program Overview Session: NSS-25

Abstract

The objective of the Neutron Radiation Detection Instrument (NeRDI) series of experiments is to space qualify and characterize the long-term performance of these new detector technologies in on-orbit radiation environments. The second of this series of experiments, NeRDI-1B, launched on 21 April 2025 to the International Space Station as part of the Department of Defense Space Test Program-Houston 10 (STP-H10) mission. The NeRDI-1B instrument comprises two arrays of Domino microstructured semiconductor neutron detectors (MSNDs), a single separate MSND sensor, and an EJ-270 plastic scintillator read out by a custom array of silicon photomultipliers. Here we describe the NeRDI-1B instrument and present an analysis of its first year of on-orbit operations, with particular focus on the characterization of the MSNDs.

Abstract

Silicon photomultipliers are increasingly replacing photomultiplier tubes in Cherenkov telescope cameras, but achieving single-photoelectron resolution with nanosecond timing in a low-noise, scalable detector system emains challenging. We present a co-designed SiPM sensor and front-end application specific integrated circuit (ASIC) that meets these requirements. The custom hexagonal sensor, developed with Hamamatsu Photonics, incorporates an integrated optical filter and fourfold pixel segmentation. The readout is performed by a second prototype of the FANSIC ASIC, optimized for this application and fabricated in 65 nm standard CMOS technology, provides eight channels with on-chip analog summing of sub-channels on a 3.5×3.5 mm2 die, while consuming only 24 mW per channel. We demonstrate clear single-photoelectron peak separation
with a gain of 2.7 × 10−12 V · s , and an impulse response below 4 ns full width at half maximum with a 1.7 ns rise time, preserving the nanosecond-scale structure of Cherenkov pulses. The system esponds linearly from 1 to 130 photoelectrons, and 55 distinct photoelectron peaks are resolved by varying the source intensity.These results demonstrate that the integrated sensorelectronics architecture delivers the speed, resolution, and dynamic range required for imaging atmospheric Cherenkov telescopes, and provides a scalable path toward large-area camera modules.

Abstract

This paper reports on the effects of thermal neutrons in a plastic-scintillator-based sampling calorimeter for a rare kaon decay experiment and the results of experimental studies demonstrating their suppression. We prepared a prototype detector consisting of a lead/scintillator sampling calorimeter with a transverse size of 25 × 25 cm² and 25 alternate layers of 1-mm-lead and 5-mm-scintillator. The prototype can accommodate 50 boron carbide sheets (0.1 mm thick), detachably mounted between the lead and scintillator layers to absorb thermal neutrons. We irradiated the prototype detector with a 0.9 GeV/c π^- beam at J-PARC and demonstrated the existence of late signals which are thought to be γ-rays from capture of thermal neutrons induced by the interaction of charged pions. Furthermore, we separately confirmed, by utilizing a radioactive neutron source, that the insertion of boron carbide sheets reduces the detection of thermal neutrons. These results demonstrate that boron loading is effective in suppressing accidental signals originating from pion-induced thermal neutrons.

Abstract

Radioactive Ion Beams (RIBs) are the frontier in Nuclear Physics, allowing investigations of low cross-section reactions and of nuclei far from the stability valley. Silicon carbide (SiC) material can overperform Silicon as a charged-particle detector, offering nearly zero leakage current and visible-light blindness thanks to the high bandgap. The high displacement energy of SiC is synonymous of radiation hardness and the saturation velocity higher than Si makes SiC an excellent material for fast, high-rate radiation detectors in nuclear and medical physics. In order to provide effectively RIBs tagging, even in the case of high intensity beams, like the ones foreseen at the Laboratori Nazionali del Sud of INFN in Catania (Italy), produced by the novel high intensity Radioactive Ion Beams (RIBs) facility named FRAISE, novel detection systems for the diagnostics and the tagging of RIBs along the transport line and in the measurement chamber are requested. To this aim and for the need of other particle accelerators around the world, we are developing a novel high performance, mid-format detection system, based on an array of Silicon Carbide (SiC) diodes, readout by an optimized fast frontend electronics. This contribution deals with the design, the study and the experimental qualification of the performance of the proposed mid-format detection system with particular care in the characterization of the timing properties and in the analysis of the limiting factors affecting the time resolution. For deposited energies above 2 MeV the time resolution keeps below 100 ps rms at zero added input capacitance. At 22pF added capacitance, the measured time resolution is below 100 ps rms above 5 MeV injected energy.

Abstract

The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed to search for low-energy cosmic antiparticles as signatures of dark matter. The GAPS instrument flew on an Antarctic long-duration balloon platform for 25 days in the 2025 austral summer, proving several novel technologies for the first time in flight. The detection method employed by GAPS involves a low-energy antiparticle slowing to a stop within the tracker, forming an exotic atom; the subsequent decay releases characteristic X-rays and nuclear annihilation products that are detectable by the instrument. GAPS utilizes a plastic scintillator time-of-flight (TOF) system that measures energy depositions and velocities and provides a system trigger, together with a tracker consisting of over 1000 lithium-drifted silicon (Si(Li)) strip detectors that provides energy and position measurements, as well as X-ray detections. The tracker operating temperature of < -35 ^oC is achieved with a novel multi-loop capillary heat pipe (MCHP) thermal system that passively transfers heat generated in the tracker to a large-area radiator. This contribution details the instrument design, performance from ground commissioning, and first Antarctic flight of the GAPS instrument.

Abstract

HYPATIA is a next-generation scintillator detector array under development for in-beam gamma-ray spectroscopy of exotic nuclei at the Rare Isotope Beam Factory (RIBF), at the RIKEN Nishina Center for Accelerator-Based Science. When completed, the array will consist of 1008 advanced scintillator detector crystals (384 HR-GAGG and 624 CeBr₃), in a hybrid configuration to deliver improved energy resolution, fast timing, enhanced background suppression and peak-to-total. This work presents the development and characterisation of CeBr₃ detector modules produced at the University of York for integration into the HYPATIA array. Each module consists of four CeBr₃ crystals coupled to silicon photomultiplier arrays within a compact, hermetically sealed housing, designed to ensure the long-term performance stability of the hygroscopic scintillators, whilst optimising the detection efficiency. Experimental characterisation demonstrates an energy resolution of 4.1% – 4.3% at 662 keV and a timing resolution of approximately 0.6 ns (FWHM) for the coincident ⁶⁰Co gamma rays. These results validate the module design and confirm its suitability for the high-precision spectroscopic measurements required to explore the limits of nuclear stability.