High efficiency neutron spectrometer with low background

Abstract

A neutron energy spectrometer with a geometry close to 4 π solid angle operated in the 1–5 MeV energy range at a configuration suitable for a “cold fusion” experiment and a very good n/γ discrimination has been constructed. Tests of registration efficiency, energy resolution and radiation type identification have been made with the help of low intensity neutron and gamma sources. The spectrometer has shown an efficiency of about 10% at 2×10 −3 s −1 background level and permits one to measure a neutron energy spectrum at a very low intensity of the source. This paper describes the physical principles, design of the neutron detector system and the results of its testing.