Characterization of Intrinsic Neutron Background in 3He detectors

Abstract

The objective of this work is to characterize the intrinsic α background for different 3He neutron detectors in order to be able to use them in low-rate neutron experiments. Isolated from atmospheric neutrons, two detectors gathered data in order to detect the background radiation without any neutron interference. Isolation from atmospheric neutrons was achieved using an experimental setup involving a polyethylene moderator and a cadmium neutron absorber. The whole experiment was performed in the Canfranc Underground Laboratory. By using Pulse Shape Discrimination methods, the intrinsic α spectrum for each detector was obtained and the α detection rates were found to be (7.9±0.3) · 10−5 s−1 and (7.7±0.3) · 10−5 s−1 respectively. Comparing these results with the ones from similar detectors portrays the need to perform this characterization for every 3He detector.