Status of <sup>48</sup>Ca double beta decay search and its future prospect in CANDLES
K. Tetsuno, S. Ajimura, K. Akutagawa, T. Batpurev, W. M. Chan, K. Fushimi, R. Hazama, T. Iida, Y. Ikeyama, B. T. Khai, T. Kishimoto, K. K. Lee, X. Li, K. Matsuoka, K. Matsuoka, K. Mizukoshi, Y. Mori, K. Nakajima, Pannipa Noithong, M. Nomachi, Izumi Ogawa, H. Ohsumi, K. Ozawa, K. Shimizu, M. Shokati, Firdaus Soberi, K. Suzuki, Y. Takemoto, Y. Takihira, Y. Tamagawa, M. Tozawa, V. T. T. Trang, S. Umehara, Kei Yamamoto, S. Yoshida, I. Kim, Do‐Hoon Kwon, H L Kim, H J Lee, M K Lee, Y. H. Kim
Abstract
Abstract CANDLES(CAlcium fluoride for the study of Neutrinos and Dark matters by Low Energy Spectrometer) is the experiment to search for the neutrino-less double beta decay(0 vββ ) of 48 Ca with CaF 2 scintillator. 48 Ca has the highest Q ββ -value (4.3 MeV) among all isotope candidates for 0 vββ . It enables us to measure signals with very low background condition. After rejection analysis with 131 days × 86 kg data for background events from radioactive contaminations in the CaF 2 scintillators, no events are observed in the Q ββ -value region. As a result, the half-life of 48 Ca is greater than 6.2 × 10 22 yr (90% confidence level). For further high sensitive measurement of 48 Ca 0 vββ search, we have been developing the 48 Ca enrichment and CaF 2 scintillating bolometer techniques. In this paper, the latest result for CANDLES and the status of scintillating bolometer development are described.