Levels in 206Po populated in the EC-β+ decay of 206At

Abstract

Levels of 84206Po122 excited in the positon decay of 85206At121 have been studied. Measured were γ-rays, conversion electrons, positons and γ-γ coincidences. Energies and relative intensities of 60 γ-rays following the decay of 206At have been measured. The positon spectrum was found to contain two branches. The total disintegration energy is 5 687±150 keV. Conversion coefficients and multipolarities of the strongest transitions have been determined. The existence of levels with the following energies in keV (spin-parities in parentheses) was deduced: 700.66(2+); 1 177.76(4+); 1 434.34(4+); 1 573.30(6+); 1 915.81; 2 100.73(4,5-); 2 138.85(4,5,6+); 2 302.57; 2 500.50; 2 581.69; 2 916.97(5,6+); 3 361.83; 3 396.45; 3 595.45(5,6+); 3 872.11; 4 038.80; 4 409.92; 4 419.53 and 4 697.84. The half-life of 206At was measured to be 29.3±0.4 m. The spin-parity of the 206At ground-state is found to be 5+.