Design of Handheld Stilbene System for Neutron Detection in a High-Gamma Field

A new stilbene scintillation composition is capable of growing to larger sizes than previously while preserving excellent PSD properties. The goal of this study is to design a stilbene-based neutron detection system that could function in an environment with a 1000-to-1 gamma-neutron ratio, and compare it to an equivalent EJ-309 liquid scintillator-based system. Separate 60Co and 252Cf sources were positioned to create the high-gamma field for each detector system, and measurements were taken as a function of lead thickness to assess the neutron detection efficiency and the gamma-ray photon misclassification rate. The stilbene was capable of functioning at a threshold as low as 36 keVee, while the EJ-309 liquid threshold needed to be raised to 62 keVee. It was also found that lead did not affect the stilbene’s PSD performance as much as it did for the EJ-309 liquid; rather, the light output threshold, double pulse cleaning, and discrimination line were stronger factors in determining its performance.