Investigation of CLYC-6 for thermal neutron detection and CLYC-7 for fast neutron spectrometry

• DOI: 10.1016/j.nima.2022.166460
• Publication Date: 2022-02-15T17:53:53Z
• Authors: Francesca Ferrulli; Marc Labalme; Marco Silari
• Keywords: CLYC-6; Pulse Shape Discrimination; CLYC-7; Fast neutron spectrometry; 0103 physical sciences; 500; [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det]; Thermal neutron counter; 540; 01 natural sciences

International audience ; Highly enriched 6 Li and 7 Li Cs2LiYCl 6 (CLYC) scintillators were investigated in view of their application as thermal neutron counter (CLYC-6) and as fast neutron spectrometer (CLYC-7) in the recently developed B-RAD radiation survey metre, an instrument designed to work in regions of high magnetic fields, currently equipped with a probe for photon dose rate measurements and γ -spectrometry. Both crystals were irradiated with a 2.5 MeV mono-energetic neutron beam from a Deuterium–Deuterium (D–D) generator and characterised in terms of neutron/ γ -ray (n/ γ ) discrimination capability by the Pulse Shape Discrimination (PSD) method, energy resolution and quenching factor. Both crystals exhibit an excellent n/ γ discrimination, quantified by a Figure of Merit higher than 2. The measured thermal energy resolution of CLYC-6 is 6%. The quenching factor for the 6 Li(n,t) α thermal neutron reaction is 0.65 and for the 35 Cl(n,p) 35 S reaction is 0.91. The measured neutron detection efficiency per unit volume of CLYC-6 is 60% higher than that of a 3 He proportional counter. CLYC-7 was tested as a fast neutron spectrometer below 10 MeV, when irradiated with continuum neutron spectra from Am–Be and 252 Cf sources. A proton/ α -particle (p/ α ) discrimination was performed exploiting the PSD technique, without any unfolding procedure. The resulting spectra match the corresponding ISO spectra better than the spectra without the p/ α discrimination, especially in the range 3 MeV to 5 MeV. A more sensitive PSD algorithm might help to improve particle discrimination at lower energies, while different reaction channels arise at higher energies preventing a spectrometry analysis.