Application of a helium scintillation counter in the neutron time-of-flight spectrometer for measurements in the 0.4-4 MeV energy range

A helium scintillation counter is described, for measuring the neutron spectra in time-of-flight in the energy range 0.4-4 MeV. The case of the counter is made of stainless steel, 2mm thick, and all its internal components are of stainless steel, teflon and brass. The counter is filled with a mixture of high purity He (90%) and Xe (10%) to a pressure of 20 atm. The pulse rise time is 15-20 ns into a 90 Ohm load in the anode of a photomultiplier. The pulse width to half-heiqht is approximately 100 ns. The technique of determining experimentally the efficiency of the counter to neutrons is considered. Experience in the combined use of the He scintillation counter and a spectrometer for measuring the spectra of time-of-flight neutrons from thick targets irradiated with 17 MeV protons, and 40 MeV α-particles, shows that the contribution of γ-radiation in the neutron spectrum is negligible (less than 1% at. O.3 MeV threshold of neutron detection, and counting rate 2.103 pulse/s)