Isomers and oblate collectivity at high spin in neutron-rich Pt isotopes
UM-DAE Centre for Excellence in Basic Sciences, Mumbai 400098, India
Published online: 19 January 2016
Isomers and high-spin structures with rotation-aligned oblate configurations have been studied in several Pt isotopes. The 12+ states in the even Pt isotopes from 192–198Pt are found to be metastable, and have (i13/2)2 neutron character. The progression of E2 transition probabilities from the 12+ to 10+ states across the Pt isotopic chain implies reduction in collectivity, followed by an abrupt decrease at N=120 (198Pt). This behavior is quite distinct from the gradual decrease of B(E2) values near the respective ground states. A large contribution from aligned angular momentum, to the rotational sequences built on the 12+ states, is visible. This is due to the relatively small crossing frequencies for nucleons in low-Ω orbitals at oblate deformation in comparison to higher values for prolate shapes. As a result, oblate rotation is found to be increasingly favored for higher neutron numbers.
© Owned by the authors, published by EDP Sciences, 2016
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