ZnO-LiF/polystyrene composite scintillator for thermal neutron radiation detection.

We report the preparation of the ZnO-LiF composite with a polystyrene (PS) polymer as a host using the solution mixing process. LiF acts as a converter material that absorbs a thermal neutron and produces alpha particles, which excites ZnO micro-particles, resulting in UV-vis photons' emission. The free-standing ZnO-LiF/PS composite film is coupled to a photomultiplier tube (PMT). Am-Be (1Ci) is used as the neutron radiation source for measuring the response. We compared the response of the composite scintillator consisting of (i) natural LiF and (ii) 95% Li enriched LiF (LiF). The increased pulse heights are recorded for 95% Li enriched, i.e., LiF converter. It confirms the generation of alpha particles after the absorption of a neutron in LiF. Furthermore, ZnO and LiF are considered in different weight proportions, 2:1, 1:1, and 1:2, keeping the total loading 50% (w/w) of polystyrene. The ZnO:LiF (1:1)/PS composite showed higher scintillation pulse heights than the other two composites. Repetitive measurements are performed for the ZnO-LiF(1:1)/PS composite, showing ±5% variation in respective responses. We also investigated the impact of different counting times and source-to-detector responses for the ZnO-LiF(1:1)/PS composite. The response increases linearly with neutron dose, exhibiting a sensitivity of ∼203 counts/μSv. Neutron measurement counts at different source-to-detector distances have a similar trend as that of neutron dose measured by using a neutron dosimeter. Thus, this work demonstrated the potential of the ZnO-LiF/PS composite, coupled to PMT for detecting thermal neutron radiation.