Performance comparison of NE213 detectors for their application in moisture measurement

The pulse shape discrimination (PSD) characteristic and neutron detection e fficiency of NE213 detectors have been measured for their application in mo isture measurements using Cf-252 and Am-241-Be sources. In PSD studies neut ron peak to valley (p(n)/V) ratio and figure of merit M were measured at fo ur different bias values for cylindrical 50, 125 and 250 mm diameter NE213 detectors. The result of this study has shown that better PSD performance w ith the NE213 detector can be achieved with a smaller volume detector in co njunction with a neutron source with smaller gamma-ray/neutron ratio. The n eutron detection efficiency of the 125 mm diameter NE213 detector for Am-24 1-Be and Cf-252 source spectra was determined at 0.85, 1.25 and 1.75 MeV bi as energies using the experimental neutron detection efficiency data of the same detector over 0.1-10 MeV energy range. Due to different energy spectr a of the 241Am-Be and 252Cf sources, integrated efficiency of the 125 mm di ameter NE213 detector for the two sources shows bias dependence. At smaller bias, Cf-252 source has larger efficiency but as the bias is increased, th e detector has larger efficiency for 241Am-Be source. This study has reveal ed that NE213 detector has better performance (such as PSD and neutron dete ction efficiency) in simultaneous detection of neutron and gamma-rays in mo isture measurements, if it is used in conjunction with 241Am-Be source at h igher detector bias. (C) 2000 Elsevier Science Ltd. All rights reserved.