Organic glass scintillator (OGS) property comparisons to Stilbene, EJ-276 and BC-404

Abstract

A new fast organic glass scintillator (OGS), recently developed at Sandia National Laboratories, has been proposed as a lower cost alternative to stilbene for detecting fast neutrons in intense gamma-ray fields, where excellent pulse-shape analysis (PSA) is required. In this paper we evaluate this proposition by measuring OGS’s scintillation properties and comparing them to three well known materials: stilbene, EJ-276, and BC-404. The measured properties were single photon light emission curves, coincidence time resolution (CTR), luminosity (photons/MeV), and figure of merit (FOM) for neutron/gamma PSA. From the light emission curves, we found that OGS has an 0.82 ns 10–90 risetime, close to EJ-276’s value of 0.81 ns and 25% faster than BC-404 and stilbene’s values at 0.96 and 1.01 ns, respectively. CTR values were measured from 75 to 325 keV, with OGS approaching 200 ps at 325 keV, compared to 250, 325 and 325 ps for BC-404, stilbene, and EJ-276, respectively. OGS had the highest luminosity, at 15,821 photons/MeV, compared to stilbene (13,054), BC-404 (8410), and EJ-276 (5522). For PSA, we studied neutron and gamma-ray pulse shapes as a function of energy and investigated various PSA algorithms, finding a properly selected tail/peak ratio to be generally best. OGS PSA FOM values were found to be twice as large as for EJ-276 and almost as good as stilbene’s – reaching 2.9, 1.5, and 3.2 at 1 MeVee respectively. Since OGS can be produced by lower cost casting techniques, this work supports further OGS development efforts.