Observation of γ vibrations and alignments built on non-ground-state configurations in 156Dy
Abstract
The exact nature of the lowest Kπ=2+ rotational bands in all deformed nuclei remains obscure. Traditionally they are assumed to be collective vibrations of the nuclear shape in the γ degree of freedom perpendicular to the nuclear symmetry axis. Very few such γ bands have been traced past the usual backbending rotational alignments of high-j nucleons. We have investigated the structure of positive-parity bands in the N =90 nucleus 156Dy , using the 148Nd(12C,4 n ) 156Dy reaction at 65 MeV, observing the resulting γ-ray transitions with the Gammasphere array. The even- and odd-spin members of the Kπ=2+ γ band are observed up to 32+ and 31+, respectively. This rotational band faithfully tracks the ground-state configuration to the highest spins. The members of a possible γ vibration built on the aligned yrast S band are observed up to spins 28+ and 27+. An even-spin positive-parity band, observed up to spin 24+, is a candidate for an aligned S band built on the seniority-zero configuration of the 02+ state at 676 keV. The crossing of this band with the 02+ band is at ℏ ωc=0.28 (1 ) MeV and is consistent with the configuration of the 02+ band not producing any blocking of the monopole pairing.
- Publication:
-
Physical Review C
- Pub Date:
- March 2015
- DOI:
- 10.1103/PhysRevC.91.034330
- arXiv:
- arXiv:2005.04706
- Bibcode:
- 2015PhRvC..91c4330M
- Keywords:
-
- 27.70.+q;
- 21.10.Re;
- 23.20.Lv;
- 23.20.En;
- 150<
- =A<
- =189;
- Collective levels;
- gamma transitions and level energies;
- Angular distribution and correlation measurements;
- Nuclear Experiment;
- Nuclear Theory
- E-Print:
- Published in Physics Review C