A high resolution, low background fast neutron spectrometer

We discuss the possibility to create a spectrometer of full absorption based on liquid scintillator doped with enriched 6Li. Of specific interest, the spectrometer will have energy resolution estimated to lie in the range 5–10% for 14 MeV neutrons. It will be sensitive to fluxes from 10−4 to 106 cm−2 s−1 above a threshold of 1 MeV in a γ-background of up to 104 s−1. The detectorʹs efficiency will be determined by the volume of the scintillator only (∼3 l) and is estimated to be 0.2–10%. The main reason for the poor resolution of an organic scintillator based spectrometer of full absorption is a non-linear light-yield of the scintillator for recoil protons. The neutron energy is occasionally distributed among recoil protons, and due to non-linear light-yield the total amount of light from all recoil protons ambiguously determines the initial neutron energy. The high-energy resolution will be achieved by compensation of the non-linear light-yield of the scintillator through the use of optically separated sections. The applications of such a detector for low-background experiments in fundamental physics research, characterizations of neutron fluence in space, and the health physics community are discussed.