Measurement of the fast neutron response for 4He scintillation detectors using a coincidence scattering method

Abstract

Time-of-flight (TOF) and coincident scattering measurements were conducted to measure the light response of a pressurized $^4{\rm He}$ fast neutron scintillation detector as a function of deposited energy up to 5 MeV. The energy deposited in the detector by a neutron was measured by its angle of scatter and compared to the resulting light output. Whereas previous research has exclusively focussed on the energy information contained in the slow component, this work demonstrates that the fast component is also sensitive to neutron energy, and the entire scintillation signal can therefore be used. The gamma rejection capability of the detector was also measured for a variety of gamma sources. The detector demonstrated a inherent gamma rejection rate of 97.31%, which was increased to 99.89% after the application of pulse shape discrimination (PSD) algorithms. The characterization of gamma rejection and light response parameters will enable implementation of these detectors for neutron spectroscopy in mixed radiation fields.