Optimum thickness of Li glass neutron detectors in mixed radiation fields

Theoretical and experimental studies were carried out to determine the optimum thickness of thin 6 Li glass scintillators using pulse amplitude discrimination to measure thermal neutrons with a minimum error in mixed neutron and gamma radiation fields. For a background count known to be 18% of the total count under the neutron peak, the optimum thickness is 1.5 mm, with the optimum thickness decreasing for increasing backgrounds. When the magnitude and spectral shape of the gamma background under the thermal neutron peak are unknown, the errors in measuring the neutron flux will increase. A distinct peak in the background occurs in a 1 mm scintillator at 0.45 MeV electron energy which is probably due to gamma radiation having energies > 0.64 MeV