Neutron Response of PARIS Phoswich Detector

We have studied neutron response of the PARIS phoswich [LaBr\(_3\)(Ce)-NaI(Tl)] detector which is being developed for measuring the high-energy (E\(_{\gamma }\) = 5–30 MeV) \(\gamma \) rays emitted from the decay of highly collective states in atomic nuclei. The relative neutron detection efficiency of LaBr\(_3\)(Ce) and NaI(Tl) crystals of the phoswich detector have been measured using the time-of-flight (TOF) and pulse shape discrimination (PSD) technique in the energy range of E\(_n\) = 1–9 MeV and compared with the GEANT4-based simulations. It has been found that for E\(_n\) > 3 MeV, \(\sim \)95 % of neutrons have the primary interaction in the LaBr\(_3\)(Ce) crystal, indicating that a clear \(\text {n}-\gamma \) separation can be achieved even at \(\sim \)15 cm flight path.