Neutrino-less Double Beta Decay of 48Ca studied by CaF2(Eu)   Scintillators
  We searched for the neutrino-less double beta decay(0nbb) of 48Ca by using CaF2(Eu) scintillators. Analysis of their pulse shapes was effective to reduce backgrounds. No events are observed in the Q-value region for the data of 3394 kg days. It gives a lower limit (90% confidence level) of T > 2.7 x 10^22 year for the half life of 0nbb of 48Ca. Combined with our previous data for 1553 kg days, we obtained more stringent limit of T > 5.8 x 10^22 year. 
S.Umehara, T.Kishimoto, I.Ogawa, R.Hazama, H.Miyawaki, S.Yoshida,   K.Matsuoka, K.Kishimoto, A.Katsuki, H.Sakai, D.Yokoyama,...