Fast neutron response of C⁷LYC: simulation and experiment

New insights into the fast neutron response of ⁷Li-enriched C⁷LYC scintillators have been obtained through detailed GEANT4 simulations of (n,p) and (n,alpha) reactions on ³⁵Cl, that are primarily responsible for the neutron response of C⁷LYC. The light output for a C⁷LYC detector was simulated and used to identify features of the different neutron reaction channels. The simulations were benchmarked against experimental data for inelastic neutron scattering data from a ¹²C target, obtained at the Los Alamos LANSCE facility, where a white neutron beam is generated by bombarding a thick W spallation target with 800 MeV pulsed protons. Fourteen 1"x1" C⁷LYC detectors were placed radially at a distance of 8" from the ¹²C scatterer. Incident neutron energies were extracted from their time-of-flight through a 20-m path from the spallation target to the ¹²C, with appropriate recoil corrections for the different detector angles, allowing a mapping of the response of C⁷LYC to mono-energetic neutrons. Resonances in the ³⁵Cl(n, p) cross-section below 3 MeV neutron energy, recently measured through the detection of the outgoing proton [1], were directly observed in C⁷LYC with similar resolution as a function of incident neutron energy.

[1] S.A. Kuvin et al, Phys. Rev. C102, 024623 (2020)