Double Beta Decay of 48Ca
48Ca, the lightest experimentally accessible double beta decay candidate, is the only one simple enough to be treated exactly in the nuclear shell model. Thus the ββ2ν half-life measurement, reported here, provides a unique test of the nuclear physics involved in the ββ matrix element calculation. Enriched 48Ca sources of two different thicknesses have been exposed in a time projection chamber. We observe a half-life of T1/22ν = (4.3-1.1+2.4[stat]±1.4[syst])×101^9 yr, consistent with shell model calculations.
©1996 The American Physical Society Received 2 August 1996 We gratefully acknowledge the hospitality of Blaine Hamann and William Sharp at the Hoover Dam. We thank Felix Boehm for his advice and support, and one of us (A. P.) wishes to acknowledge the support of the Alexander von Humboldt Foundation. This work was funded by the U.S. Department of Energy under Contracts No. DE-FG03-01ER40679 and No. DE-FG03-88ER40397.