Author:
Umehara S.,Nomachi M.,Kishimoto T.,Ajimura S.,Takemoto Y.,Tetsuno K.,Takihira K.,Matsuoka K.,Trang V. T. T.,Yoshida S.,Shokati M.,Li X.,Batpurev T.,Khai B. T.,Lee K.,Akutagawa K.,Soberi F.,Mizukoshi K.,Yamamoto K.,Tamagawa Y.,Ogawa I.,Nakajima K.,Tozawa M.,Shimizu K.,Shimizu K.,Mori Y.,Ikeyama Y.,Ozawa K.,Matsuoka K.,Iida T.,Fushimi K.,Hazama R.,Noithong P.,Suzuki K.,Ohsumi H.
Abstract
Abstract
We have studied the neutrino-less double beta decay(0νββ) of 48Ca with the CANDLES III system, which consists of CaF2(pure) scintillators. Rejection analyses for background events from radioactive contaminations in the CaF2(pure) scintillators were effective to reduce backgrounds in Qββ
-value region. As the results, no events were observed in the region for the data of 131 days × 86 kg. It gave a lower limit 6.2 × 1022 year (90 % C.L.) for the half-life of 0νββ of 48Ca. For higher sensitive measurement of 48Ca 0νββ, we have developed new techniques for 48Ca enrichment and CaF2 scintillating bolometer. In this paper, we will also show current status of these techniques.
Subject
General Physics and Astronomy