Analysis of pulse shapes in a plastic scintillator with efficient neutron/gamma pulse shape discrimination.

A sample of the new plastic scintillator recently formulated by Zaitseva et al., and shown by them to have efficient pulse shape discrimination properties, was exposed to neutron and gamma radiation, and the pulse shapes recorded by a digitising oscilloscope. Separate average neutron and gamma pulse shapes were derived, and then a theoretical pulse shape formula, based on the proportions and lifetimes of excitations within the scintillator, was fitted to the experimentally-measured shapes. The results of these fits lend support to the commonly accepted description of the mechanism underlying neutron / gamma pulse shape differences in organic scintillators, and provide numerical estimates of the proportions and lifetimes of the scintillator excitations.