Calibration of neutron spectrometers based on a BC-501A liquid scintillator using the neutron-gamma coincidence method

摘要

Two neutron spectrometers based on a BC-501A liquid organic scintillator were calibrated. The calibration procedure included obtaining the spectrometers' response functions to monoenergetic neutron emissions and estimating the detectors' efficiency and is described in this paper. A~9 Be(α, nγ)~(12)C nuclear reaction was used as the neutron source. Simultaneous registration of neutrons and gamma quanta with 4.44 MeV energy enabled the extraction of monoenergetic neutrons corresponding to the first excited state of a ~(12)C nucleus. This process is the basis of the neutron-gamma coincidence method, which was applied in the present experiments. The experiments were conducted using the cyclotron at Ioffe Institute, where α particles were accelerated to energies of 2.06, 5.35, 6.05, and 10.08 MeV. The angular dependence of the energy of produced neutrons provided a wide energy range of monoenergetic neutron emission at the same energy of the incident α particle. The response functions of the BC-501A spectrometers on the monoenergetic neutrons were obtained at energies of 1.9 to 10.4 MeV. The neutron registration efficiency of both detectors was estimated in the same energy range as the responses.