Levels in 179Ta and γ-ray transition probabilities in 179Ta and 183Re

Abstract

The level scheme of the deformed odd-proton nucleus 179Ta has been investigated by inbeam spectroscopic methods. Single γ-ray spectra as well as prompt and delayed γ-γ coincidences were measured in the reactions 179Hf(d, 2n) and 179Hf(p, n). The proposed level scheme of 179Ta contains, in addition to the ground state band 7 2 + [404], the rotational bands built on the intrinsic states 9 2 − [514], 5 2 + [402], 1 2 + [411] and 1 2 − [541]. By nanosecond lifetime measurements with Ge(Li) detectors the following half-lives have been obtained for 179Ta levels: T 1 2 (238.6 keV) = 95 ± 5 ns , T 1 2 (520.3 keV) = 350 ± 20 ns , T 1 2 (628.1 keV) = 80 ± 10 ns . A three-quasi-particle state of T 1 2 = 8.6 ± 1 ms with spin and parity tentatively assigned as I π = ( 19 2 , 21 2 ) − has been identified at an excitation energy of 1253.3 keV. For the 5 2 1 2 − [541] level in 183Re, excited in the reaction 181Ta(α, 2n), a lifetime of T 1 2 = 2.0 ± 0.1 ns was measured.