Tl-Doped CsI/⁶LiBr Scintillator for Thermal Neutron Detection With Ultrahigh Light Yield

In this study, a novel thermal neutron scintillator of Tl:CsI/LiBr was developed. The eutectics were fabricated at various growth rates and investigated their scintillation properties. As a material design guideline, Tl:CsI, which has an excellent \alpha /\gamma ratio, was selected as the scintillator phase to realize high light yield at the energy of \alpha -rays and tritons generated by the nuclear transmutation reaction with 6 Li and LiBr, which has a refractive index close to that of CsI, was selected as the neutron capture phase. Radioluminescence (RL) measurement under X-ray irradiation was also performed to obtain the emission spectrum of the eutectics. The light yield and decay time for thermal neutron were measured using 252 Cf and were much higher than those of conventional scintillators for thermal neutron. Furthermore, fabricated eutectic can have the higher sensitivity to thermal neutron due to the high 6 Li concentration compared to conventional single-crystal scintillators. Therefore, we have succeeded in developing a promising scintillator material.