A hybrid pulse shape discrimination technique with enhanced performance at neutron energies below 500 keV

A hybrid pulse shape discrimination (PSD) method is presented that combines a charge-integration PSD method with a reference-pulses PSD method. The reference-pulses PSD method uses detailed knowledge of the average, energy-dependent detector response to radiation. To obtain the reference-pulses, a large number of neutron and gamma-ray pulses was averaged in several pulse height regions. The reference neutron and gamma-ray pulses were then used in the new PSD method for the classification of a large number of measured pulses. The reference-pulses PSD method was applied below 70 keVee, whereas the standard charge-integration PSD method was used above 70 keVee. This new hybrid PSD method proves to be more accurate than the standard charge-integration PSD method for classification of neutrons and gamma rays. Specifically, the improvement is approximately 30% for neutrons in the smallest pulse height bin considered, which was between 20 and 30 keVee (corresponding to approximately 150 and 225 keV neutron energy deposited, respectively). For this pulse height bin. approximately 72% of the neutrons were correctly classified by the hybrid PSD method. The average number of correctly classified neutrons is approximately 88% for the hybrid PSD method between 20 and 100 keVee (corresponding to approximately 150 and 670 key neutron energy deposited, respectively) as opposed to 83% for the charge-integration PSD method. Published by Elsevier B.V.