A Limit of Neutrinoless Double Beta Decay of ~(48)Ca

A search for the neutrinoless double beta decay of ~(48)Ca is carried out in a coal mine which is located 512m underground near Beijing. Large scintillation crystals of natural CaF_2 were used as both the detector and the double beta decay source. Result obtained after a total of 7588.5 hours of data taking gives 1.1×10~(22) years (68% C. L.) as the lower limit of the half-life of the neutrinoless double beta decay of ~(48)Ca.