Beta decay of 187W

Abstract

Coincidence studies have established in the decay scheme of,187W the existence of transitions of energy 7, 36, 77, 455, 589, and 639 keV with intensities of 3.0 ± 0.5%, 0.50 ± 0.06%, 0.31 ± 0.07%, 0.05 ± 0.02%, 0.14 ± 0.04%, and 0.05 ± 0.02% respectively as well as yielding the absolute intensities of the well-known transitions in 187Re. In addition the beta–gamma coincidence measurements have shown that (1) a first-forbidden unique transition feeds the first-excited state of 187Re, (2) there is at most a very weak beta transition to the level at 512 keV, (3) there is no inner beta group of about 300 keV end-point energy and intensity 8% as indicated by several earlier investigations, and (4) the decay energy of 187W to 187Re is 1311 ± 2 keV. The relevance of these observations to the structure of 187Re is discussed.