A liquid scintillator containing a tetrakis (isopropyl acetoacetato) zirconium has been developed for ZICOS experiment. In order to reach the sensitivity T10/ν2 ≥ 1027 years, we have to use tone scale of 96Zr and have to reduce 95 % of 208Tl decay background. Using Monte Carlo simulation, we could demonstrate new method using the topological information of Cherenkov light, and could reduce 93 % of 208Tl background with 78 % efficiency for 0νββ signal. For the discrimination of Cherenkov light, the precise spectral pulse shape from Cherenkov lights was directly measured by using sub-MeV electrons from 90Sr/90Y beta source. The observed shape was clearly different from the shape of scintillation light. The pulse rise and fall (decay) time for Cherenkov light were 0.8 ns and 2.5 ns, respectively. They were actually shorter than those times of scintillation light which were also measured by 1.6 ns and 6.5 ns, respectively. This clear difference of rise time will be used for the pulse shape discrimination in order to select PMT which receive Cherenkov lights, and the topological information due to Cherenkov light will be used for the reduction of backgrounds from 208Tl decay which should be major backgrounds observed around Q-value (3.35MeV) of 96Zr neutrinoless double beta decay.
|ジャーナル||Proceedings of Science|
|出版ステータス||Published - 2019|
|イベント||2019 European Physical Society Conference on High Energy Physics, EPS-HEP 2019 - Ghent, Belgium|
継続期間: 2019 7 10 → 2019 7 17
ASJC Scopus subject areas