MEASUREMENTS ON K-ELECTRON CAPTURE PROBABILITIES IN THE DECAY OF AU-196 AND HG-197

The K-electron capture probabilities in the decay of Au-196 characteri sing 2 --> 2+ non-unique first forbidden transitions to the levels 688 .7 and 355.7 keV in the daughter Pt-196 were measured for the first ti me using the X-gamma summing method. The respective PK values are foun d to be 0.776 - 0.038 and 0.847 +/- 0.051 in agreement with the theory . The K-electron capture probability for the non-unique first forbidde n transition 1/2 --> 1/2+ in the decay of Hg-197 to the 77.35 keV leve l in the daughter Au-197 was measured to be 0.778 +/- 0.014 in agreeme nt with the theory.