  An organic glass scintillator developed by Sandia National Laboratories was
characterized in terms of its light output and pulse shape discrimination (PSD)
properties and compared to commercial liquid (EJ-309) and plastic (EJ-276)
organic scintillators. The electron light output was determined through
relative comparison of the $^{137}$Cs Compton edge location. The proton light
yield was measured using a double time-of-flight technique at the 88-Inch
Cyclotron at Lawrence Berkeley National Laboratory. Using a tunable
broad-spectrum neutron source and an array of pulse-shape-discriminating
observation scintillators, a continuous measurement of the proton light yield
was performed for EJ-309 (200 keV$-$3.2 MeV), EJ-276 (170 keV$-$4.9 MeV), and
the organic glass (50 keV$-$20 MeV). Finally, the PSD properties of the organic
glass, EJ-309, and EJ-276 were evaluated using an AmBe source and compared via
a figure-of-merit metric. The organic glass exhibited a higher electron light
output than both EJ-309 and EJ-276. Its proton light yield and PSD performance
were comparable to EJ-309 and superior to that of EJ-276. With these
performance characteristics, the organic glass scintillator is well poised to
replace current state-of-the-art PSD-capable scintillators in a range of fast
neutron detection applications.
