Abstract
Double beta decay of has been confirmed and the ratio of half-lives for ββ decay of and has been precisely determined as /=(3.52±0.11)× by ion-counting mass spectrometry of Xe in ancient Te ores, using techniques that reduce interferences due to trapped Xe. We have also detected excesses of originating in high energy reactions of cosmic ray muons and their secondaries on Te; such reactions make minor contributions to the measured excesses in the Te ores. The Xe measurements, combined with common Pb dating of the ores, yield a half-life of (2.7±0.1)× yr and thus a half-life of (7.7±0.4)× yr, the longest radioactive decay lifetime measured to date. These results give limits on the effective Majorana mass of the neutrino (<1.1–1.5 eV) and right-handed currents (‖〈η〉‖<5.3×) comparable to the best obtained from direct neutrinoless ββ-decay searches. They also imply new limits on unconventional Majorons not constrained by measurements of the decay width.
- Received 18 September 1992
DOI:https://doi.org/10.1103/PhysRevC.47.806
©1993 American Physical Society