Evaluation of a quenching coefficient in Li-containing scintillators

Watanabe, Kenichi*; Oshima, Yuya*; Hirata, Yuho   

Li has a high cross section for thermal neutrons and undergoes the Li(n, t) alpha reaction. This reaction is important in thermal neutron detection, and scintillator materials containing Li are widely used for neutron detection. However, the luminescence efficiency for the tritons and alpha-particles emitted from the Li(n, t) alpha-reaction is reduced due to the quenching effects. This makes it difficult to separate the emission of particles generated by background gamma-rays and neutrons by the amount of luminescence. Although, the alpha/beta ratio has been used as a conventional index to evaluate the quenching effect of scintillators for neutrons, it is insufficient for small scintillators because it does not fully reflect the effect of alpha and triton particles on the luminescence. In this study, we adopted Birks equation as a model for the quenching effect, simulated the quenching effect using the Monte Carlo simulation code PHITS, and compared the obtained signal wave height distributions with experimental results.