Measurement of neutrons down to 200 keV with pulse shape discrimination using an EJ-301 liquid scintillator

Abstract

Pulse shape discrimination is a method commonly used to separate gamma and neutron signals in liquid scintillation detectors. The method works well for neutrons above 500 keV, but as the energy deposited in the detector decreases, so does the effectiveness. In order to utilize pulse shape discrimination capabilities at lower energies, a 1.27 cm thick EJ-301 detector operated at a bias voltage of 2200 V has been used. The detector has been shown to have an average misclassification of 0.5% of gamma pulses over the total energy range from 35 keVee to 400 keVee, and 2.0% in the most sensitive region from 35 keVee to 45 keVee. A measurement performed using the time-of-flight method at the Gaerttner Linear Accelerator Facility at Rensselaer Polytechnic Institute has shown that with the pulse shape discrimination method, this detector can detect and characterize neutron pulses down to 200 keV.