Neutrino-less double-{beta} decay of {sup 48}Ca studied by CaF{sub 2}(Eu) scintillators

We searched for the neutrino-less double-{beta} decay(0{nu}{beta}{beta}) of {sup 48}Ca by using CaF{sub 2}(Eu) scintillators. Analysis of their pulse shapes was effective to reduce backgrounds. No events are observed in the Q{sub {beta}}{sub {beta}} value region for the data of 3394 kg {center_dot} day. It gives a lower limit (90% confidence level) of T{sub 1/2}{sup 0{nu}}{sup {beta}}{sup {beta}}>2.7x10{sup 22} year for the half-life of 0{nu}{beta}{beta} of {sup 48}Ca. Combined with our previous data for 1553 kg {center_dot} day [I. Ogawa et al., Nucl. Phys. A730, 215 (2004)], we obtained a more stringent limit of T{sub 1/2}{sup 0{nu}}{sup {beta}}{sup {beta}}>5.8x10{sup 22} year.