Abstract
A dramatic reduction in background was achieved in the latest Pacific Northwest Laboratory–University of South Carolina germanium detectors. Two 1.05-kg natural-isotopic-abundance detectors were operated for 1.92 kg yr. The residual spectrum, after straightforward corrections, has a significant region resembling the theoretical spectrum of the two-neutrino ββ decay of . A fit to the data yields Ge)=(1.)× yr at the 95% C.L., which agrees with shell-model predictions.
- Received 5 September 1990
DOI:https://doi.org/10.1103/PhysRevLett.65.3092
©1990 American Physical Society