Abstract
The low-lying positive- and negative-parity states in have been investigated by means of the fusion evaporation reaction. Using the coincidence method, the level scheme was corrected and extended up to 3 MeV, for both the positive- and negative-parity states. Using the new branching ratios determined in the present experiment, the quantum number was proposed for two negative-parity bands by direct comparison with the Alaga rule. Like in some other nuclei, one negative-parity band was established, decaying predominantly to the -vibrational band. In a second experiment, the lifetimes of the low-lying excited states up to in the ground-state band were measured by using the in-beam fast-timing method with the Bucharest mixed high-purity germanium (HPGe) and :Ce detector array using the triple- coincidence method. Reduced transition probabilities were extracted from the measured lifetimes and compared with the corresponding observables in neighboring isotopes, showing a smooth behavior with increasing mass. The positive- and negative-parity states as well as and transition probability ratios revealed by these experiments are compared with the interacting boson model in the and boson space, and with the confined beta-soft rotor model, and are found to be in good agreement.
1 More- Received 1 October 2014
- Revised 26 February 2015
DOI:https://doi.org/10.1103/PhysRevC.91.034321
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