Fast Neutron Spectroscopy Using ${\rm Cs}_{2}{\rm LiYCl}_{6}{:}{\rm Ce}$ (CLYC) Scintillator

The response of Cs₂LiYCl₆:Ce (CLYC) scintillator material to fast neutrons has been measured using a Van de Graaff accelerator. Beams of monoenergetic neutrons in the energy range 0.359 MeV to 4.703 MeV were used to irradiate a 9 mm × 9.5 mm × 12 mm CLYC crystal. Following pulse-shape discrimination to separate neutron and gamma-ray events, peaks are observed in the neutron spectrum and assigned to fast-neutron events in the scintillator. One of the peaks is interpreted as being due to the ³⁵Cl(n, p)³⁵S reaction, and it is shown that the proton energy released in this reaction varies linearly with the energy of the incoming neutron. The linearity of the response may enable CLYC to be used for fast-neutron spectroscopy with well defined spectral peaks. The response of CLYC to thermal neutrons and gamma rays is well known, and the material has potential for simultaneous thermal-neutron detection, fast-neutron spectroscopy, and gamma-ray spectroscopy.