Depopulation of the J^π = 9^- isomer in ¹⁸⁰Ta to the J^π = 1⁺ ground state by Coulomb excitation

In-beam Coulomb excitation of the exotic odd-odd nucleus Ta-180 has been studied by using a Xe-136 beam and a setup consisting of five EURO B ALL CLUSTER detectors and the Darmstadt-Heidelberg Crystal Ball array. Spectroscopic information on the extremely rare Ta-180 is obtained from the comparison between an enriched (3.6 +/-0.3% Ta-180) and a natural tantalum target. Possible evidence for a depopulation from the long-lived high-spin J(pi) = 9(-) isomer to the short-lived J(pi) = 1(+) ground state is searched for by different methods. The decay of low-K bandheads, which are nanosecond isomers, towards the groundstate band can be demonstrated in delayed spectroscopy. A gamma gamma coincidence analysis provides indications of K = 5 in-band transitions. Finally, when the Crystal Ball is used as an energy and gamma multiplicity filter, signals of decay into the K = 0 band are observed.