States in 176Hf Populated by the (a,2n) Reaction

Abstract

The level structure of the even-even deformed nucleus 176Hf has been studied by means of the 174yb (a,2n) 176Hf reaction through y-ray singles, conversion electron and extensive prompt and delayed y-y coincidence measurements. The half-lives of the isomeric states a·t 1333 and 1559 keV have been measured as 9.5 and 9.8 usec, respectively. Besides the ground state rotational band, the following ten rotational bands have been established: two K=0+ bands at 1150 keV and 1293 keV, a K=2+ band at 1341.1 keV, a K=3+ band at 1577.3 keV, a K=2-octupole band at 1247.5 keV, two K=6+ bands of mixed neutron and proton character at 1333.1 keV and 1761.5 keV, a K=8- band at 1559.4 keV, a K=8- and/or 7- band at 1860.3 keV and a K=7-and/or 6- band at 1798.0 keV. The de-excitation of the high K states proceeds through either of the two isomers, and were studied by novel experimental techniques which involved pulsing the alpha beam. The intrinsic structure and decay properties of the states are understood in terms of the unified model. In some cases it has been necessary to make use of unpublished McMaster results from the single neutron and proton transfer reactions.