Status of $^{48}$Ca double beta decay search with CANDLES

Umehara, Saori; Fushimi, Ken-Ichi; Harada, Takaaki; Hashimoto, Akihiro; Hazama, Ryuta; Hiraiwa, Tasuku; Iga, Tomoki; IIda, Takashi; Kawashima, Yusuke; Kishida, Yumiko; Kishimoto, Tadafumi; Matsuoka, Kenji; Miyoshi, Go; Muramatsu, Yoshiki; Nakajima, Kyohei; Nomachi, Masaharu; Ogawa, Izumi; Rittirong, Anawat; Sakai, Toshiki; Sakaue, Akitoshi; Suzuki, Kohtaku; Takihira, Yukichi; Tamagawa, Yoichi; Tozawa, Masashi; Yamamoto, Asahi; Yoshida, Sei; Yoshida, Tomomi; Yoshioka, Atsushi

doi:10.22323/1.380.0291

Abstract

We have studied the neutrino-less double beta
decay(0

$\nu\beta\beta$ ) of

$^{48}$ Ca
with the CANDLES III system, which consists of CaF

$_{2}$ (pure) scintillators.
The first result of

$^{48}$ Ca double beta decay with the CANDLES III system
was obtained by using 130.4 days of data.
In this measurement,
we achieved a background free measurement
and a low background condition of 10

$^{-3}$ events/keV/yr/(kg of

$^{\rm nat.}$ Ca).
The sensitivity of this measurement, however, was limited by the small amount of

$^{48}$ Ca.
For a more sensitive measurement of

$^{48}$ Ca 0

$\nu\beta\beta$ ,
we have developed new techniques for

$^{48}$ Ca enrichment
and CaF

$_{2}$ scintillating bolometer.
In this paper, we will also show the current status of these techniques.