Glass That Sees Thermal Neutrons express
Neutrons leave no trace in ordinary glass: they pass right through, like light through a window pane. But some materials flash a faint burst of light when a particle hits them. That's how a scintillator works: a substance that turns invisible radiation into visible light.
The new transparent glass SG101 is one such material. It is especially sensitive to thermal neutrons — slow particles that have lost energy and move at the speed of air molecules in a room. In tests with an AmBe neutron source, the glass caught these particles and emitted flashes that electronics registered.
To tell useful signals from noise, SG101 was paired with organic scintillators EJ200 and EJ276. The result was a system that sorts radiation into categories: gamma rays, fast neutrons, and thermal neutrons. For the SG101+EJ200 pair, the quality of gamma/thermal neutron separation reached 3.81 on the FOM scale (higher means cleaner separation). With EJ276, it distinguished all three particle types with scores of 3.46 and 2.21.
Further analysis showed that events where a thermal neutron arrives together with a fast neutron or a gamma quantum occur much more often than random coincidences would predict. This confirms the detector truly sees correlated physical processes, not noise.
This material will be useful where you need to know exactly how many thermal neutrons arrived and when — for example, at research reactors or in nuclear material control systems.
Original abstract
as written by the authors arXiv:2602.11597
We present a detailed characterization of the thermal neutron sensitive transparent glass scintillator SG101, benchmarked against the conventional LiF ZnS(Ag)based scintillator EJ426. The detection efficiency, energy resolution, and pulse shape discrimination (PSD) performance ofSG101 were evaluated under AmBe neutron irradiation. When coupled with organic scintillators(EJ200 or EJ276),the SG101 EJ200 system achieves a figure of merit (FOM) of 3.81 for thermal neutron/gamma separation, while the SG101 EJ276 configuration resolves three distinct particle populations gamma rays, fast neutrons, and thermal neutrons with FOM values of 3.46 and2.21, respectively. Correlation analysis reveals that the number of fast thermal neutron coincidence events significantly exceeds the accidental background, and the count of gamma fast thermal neutron triple-coincidence events is also far higher than the expected accidental rate, confirming significant physical correlations for both event types within a 100 us time window. These results demonstrate that SG101 is a promising candidate for applications requiring high-efficiency thermal neutron detection and precise event tagging coupling with a scintillator with PSD approach
Thermal neutrons travel at about 2.2 km/s — a hundred times slower than fast neutrons from nuclear reactions.