DOUBLE-BETA DECAY OF CA-48

Ca-48, the lightest experimentally accessible double beta decay candid ate, is the only one simple enough to be treated exacly in the nuclear shell model. Thus the beta beta(2v) half-life measurement, reported h ere, provides a unique test of the nuclear physics involved in the bet a beta matrix element calculation. Enriched Ca-48 sources of two diffe rent thicknesses have been exposed in a time projection chamber. We ob serve a half-life of T-1/2(2v)=(4.3(-1.1)(+2.4)[stat]+/-[syst])x10(19) yr, consistent with shell model calculations.