Open AccessDelayed coincidence with a day-scale window for tagging 232Th series isotopes in KamLAND
Author(s) -
Takahiko Hachiya
Publication year - 2020
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1468/1/012257
Subject(s) - coincidence , physics , nuclear physics , scintillator , coincidence counting , neutrino , isotope , detector , particle physics , optics , medicine , alternative medicine , pathology
Decays of 232 Th series isotopes such as 212 Bi 212 Po and 208 Tl form background events for underground physics experiments. In this study, we performed new delayed coincidence with a day-scale window using data of KamLAND, a 1 kton liquid scintillator detector. We firstly searched for a coincidence of 220 Rn– 216 Po (T 1/2 = 0.15 s), prompt coincidence (PC), and then searched for events of 212 Bi 212 Po or 208 Tl decays within 2 day from PC. It yields ~80% tagging efficiency with modest, ~10%, deadtime despite the requirement of long time correlation thanks to low accidental coincidence rate of PC. This method will be newly introduced to analyses of solar neutrino measurement at 3 MeV region with KamLAND and neutrinoless double-beta decay search with KamLAND-Zen to reduce the backgrounds.