Multi-layer plastic scintillation detector for intermediate- and high-energy neutrons with $\it{n}$-$\gamma$ discrimination capability

摘要

A new type of neutron detector, named Stack Structure Solid organicScintillator (S$^4$), consisting of multi-layer plastic scintillators withcapability to suppress low-energy $\gamma$ rays under high-counting rate hasbeen constructed and tested. To achieve $\it{n}$-$\gamma$ discrimination, weexploit the difference in the ranges of the secondary charged particlesproduced by the interactions of neutrons and $\gamma$ rays in the scintillatormaterial. The thickness of a plastic scintillator layer was determined based onthe results of Monte Carlo simulations using the Geant4 toolkit. With layerthicknesses of 5 mm, we have achieved a good separation between neutrons and$\gamma$ rays at 5 MeV$_{\rm ee}$ threshold setting. We have also determinedthe detection efficiencies using monoenergetic neutrons at two energiesproduced by the $\it{d}$+$\it{d}\to\it{n}$+$^{3}$He reaction. The results agreewell with the Geant4 simulations implementing the Li$\grave{\rm e}$geIntranuclear Cascade hadronic model (INCL++) and the high-precision model oflow-energy neutron interactions (NeutronHP).