Weak decay of 130Ba and 132Ba:: Geochemical measurements -: art. no. 035205

The half-life of Ba-130 due to multichannel weak decay (2B(+), 2EC, and EC beta (+)) has been determined for the first time by the measurement of the Xe-130 daughter accumulated in natural barite (BaSO4) from the Belorechenskoe deposit in North Caucasus, Russia. The accumulation time was determined from U-Xe and K-Ar gas-retention ages measured in the same material. yielding a half-life for Ba-130 for all weak decay modes of 2.2+/-0.5 X 10(21) yr (68% C.L.), about a factor of 2 lower than that predicted by the proton-neutron quasiparticle random phase approximation. From excess Xe-132 observed in this barite, the half-life for weak decay of Ba-132 can be estimated (T-1/2 = 1.3+/-0.9 X 10(21) yr). However, this value is more tentative. since other sources of this isotope cannot be excluded, but the lower limit of 2.2X10(21) yr remains firm.