Studies on the response of 3He and 4He proportional counters to monoenergetic fast neutrons

Two helium filled proportional counters (3He and 4He) were studied to establish the optimum operating conditions when these counters are used for fast neutron measurements, as well as to examine the linearity of the pulse height with neutron energy. The detectors were irradiated with mono-energetic neutrons in the energy range of 230 keV–22 MeV, produced via 7Li(n,p)7Be, 2H(d,n)3He and 3H(d,n)4He reactions in a Tandem Van de Graff accelerator. The gamma ray contribution to the obtained pulse height distribution and the resolution of the counters as a function of shaping time constant and applied high voltage were studied.