Characterization of CaMoO4 Crystals for the 0-neutrino Double Beta Decay Search

Characteristics of CaMoO4 scintillation crystals were studied for the 0-neutrino double beta decay search of 100Mo nuclei. Among variety of inorganic scintillation materials containing Mo with the structure of sheelite or wolframite, CaMoO4 shows brightest scintillation light. We measured light yield and decay time of CaMoO4 crystals grown with different conditions using various radioactive sources. We also showed that alpha particles and gamma rays can be separated using the different time characteristics of the crystal which is useful for reduction of 208Tl and 214Bi radioactive decay background. Internal background of a CaMoO4 crystal was measured for several months with the shielding of 30cm thick mineral oil, 15cm thick lead and 5cm thick polyethylene at the 750 minimum depth of underground laboratory in YangYang Stored Water Power Plant in Korea. The 100Mo nuclei has a Q-value of 3.034 MeV and it's the best half life limit is 5x1022 years. Significant improvement of sensitivity of 0-neutrino double beta decay can be achieved by using several kilograms of 100Mo enriched CaMoO4 crystals with good energy resolution and low background