Double beta decay of $^{48}$Ca in CANDLES III - Construction and first run -

Experiments of neutrino oscillation show that neutrinos have mass. The absolute mass scale and Majorana nature of neutrino are of current interests. The measurement of neutrino-less double beta decay can establish the Majorana nature of neutrino and is the realistic experiment to measure the effective mass in the range of meV, so far. We have been studying double beta decay of $^{48}$Ca. The highest Q-value of $^{48}$Ca among double beta decay nuclei makes it possible to realize background free measurement. CANDLES (\underline {CA}lcium fluoride for the study of \underline {N}eutrino and \underline {D}ark matter by \underline {L}ow \underline {E}nergy \underline {S}pectrometer) system was proposed, in order to achieve the sensitivity of order of meV neutrino mass. In this system, CaF$_{2}$ crystals are immersed in liquid scintillator. We started studying of neutrino-less double beta decay by using CANDLES III that consists of 60 undoped CaF$_{2}$crystals with total mass of 191kg. The present status of construction and performance of CANDLES III in the first run will be reported.