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High-spin properties of Er164 in the multiple band crossing region
Journal article   Peer reviewed

High-spin properties of Er164 in the multiple band crossing region

S. W Yates, I. Y Lee, N. R Johnson, E Eichler, L. L Riedinger, M. W Guidry, A. C Kahler, D Cline, R. S Simon, P. A Butler, …
Physical review. C, Nuclear physics, Vol.21(6), pp.2366-2384
06/1980
DOI: 10.1103/PhysRevC.21.2366

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Abstract

High-spin states in 164Er have been studied by using the 150Nd(18 O,4n ) and 164Dy(α,4ny) reactions and by multiple Coulomb excitation with 136Xe ions. Several positive-parity bands are excited, and two negative-parity bands have been identified. The previously reported backbending behavior of the yrast sequence is demonstrated to result from the intersection of the ground band (seen to spin 22+) with an even-spin "superband" observed from spins 12+ to 24+. The odd-spin yrast superband and the second lowest even-spin superband also have been observed. All the superbands have moments of inertia appreciably larger than the ground band. The observed intersection of these multiple superbands with the y band produces different backbending behavior and a staggering of the energies of the odd- and even-spin members of the y band. B(E2) values for transitions below and through the band intersection regions of both the ground band and y bands have been deduced from multiple Coulomb excitation yields. In addition, lifetimes have been measured for the ground band by the Doppler-broadened line-shape technique. The level energies and B(E2) values are consistent with weak interaction matrix elements (-45 keV) between the intersecting bands. The B(E2) values of the unperturbed band are found to obey the simple rigid-rotor relationship. The 7-- negative-parity band exhibits a normal rotational sequence, while the 5 -- band exhibits a large odd-even staggering and a larger moment of inertia. Two-quasiparticle-plus-rotor model calculations indicate strong rotation-alignment and reproduce the observed properties of the high-spin states for both the positive- and negative-parity bands in 164Er.

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