Study on pulse shape discrimination power of plastic scintillators

Abstract

Nuclear reactor safeguard, based on detection of electron antineutrino flux and energy spectrum, is of great interests to both administrative agencies such as International Atomic Energy Agency (IAEA) and neutrino community. A dominant reaction channel of such detection is inverse beta decay (IBD), for which discrimination of gamma against neutron is critical. In this study, pulse shape discrimination (PSD) is used over plastic scintillator, for its ease of detector assembly, no risk of leakage, and high chemical stability. Using 22Na and 137Cs radioactive sources to calibrate the energy response of the whole system (data acquisition and materials), EJ200 and EJ426 scintillator combination is used as the discrimination setup. The figure of merit (FOM) can reach 9.13 ± 0.01, and could be adopted to build a reactor neutrino safeguard detector. In addition, the PSD of two kinds of plastic scintillators were compared. The FOM of the EJ276 plastic scintillator can reach 1.35 ± 0.01 at the energy threshold of 1 MeV gamma equivalent in comparison to 0.96 ± 0.01 of UPS-113NG at the same energy threshold.