Multiphononγ-vibrational bands and the triaxial projected shell model

Nature ofγdeformation in Ge and Se nuclei and the triaxial projected shell model description

“…However, the TPSM is a fully microscopic theory, and fixed deformations are only used for construction of basis states. It is important to note that unlike the phenomenological asymmetric rotor model [6], our results depend not only on the deformation parameters but also on the detailed microscopic isotopedependent shell filling, and more importantly, on the configuration mixing of the various quasiparticle states [18,30]. We would also like to remind here that in the spherical shell model approach, although, starting from a bare spherical basis, it can equally describe the deformed nuclei as well.…”

“…Nevertheless, this model is clearly an over-simplified approach. It has been pointed out [18,30] that the underlying physical picture of generating γ-vibration in deformed nuclei, suggested in the framework of TPSM, is analogous to the classical picture of Davydov and Filippov [6], yet TPSM is a fully microscopic method. It is interesting to see that both shell models (SSM and TPSM), though starting from quite different bases (spherically symmetric vs. triaxially deformed) give nearly identical results for the low-lying states of 76 Ge, as seen in Figs.…”

“…A triaxial qp con- 35.84 figuration is an admixture of different K (projection along the symmetry axis) states, and the vacuum configuration is composed of K = 0, 2, 4, ... states for an even-even system. It was shown [18] that the angular-momentum projection from the K = 0, 2, and 4 states correspond to the ground, γ-and γγ-bands, respectively. The model has recently been extended [13-17, 19, 20] to include multi-qp configurations in the model space, which allows one to describe states of collective γ-vibrations and qp excitations on an equal footing.…”

“…In the next section, we provide a few details of the TPSM model for completeness and further details can be found in our earlier publications [13][14][15][16][17][18]. Section III is completely devoted to the investigation of 76 Ge and in section IV, the results of the neighboring Ge-and Se-isotopes are presented and discussed.…”

High-spin structure and multiphononγvibrations in very neutron-richRu114

“…It has been shown that TPSM calculations with triaxially deformed basis can naturally describe multi-phonon γ-vibrations [23]. TPSM with multi-quasiparticle (qp) configurations in the model has recently been developed and applied successfully in different mass regions for eveneven [24,25] and odd-mass nuclei [26].…”