Projected shell model description for high-spin states in neutron-rich Fe isotopes

Abstract

A systematic study of neutron-rich even-even Fe isotopes with a neutron number from 32 to 42 is carried out by using the projected shell model. Calculations are performed up to the spin I = 20 state. Irregularities found in the yrast spectra and in B (E2) values are discussed in terms of neutron excitations to the high-j orbital g 9/2 . Furthermore, the neutron two-quasiparticle structure of a low-K negative-parity band and the proton two-quasiparticle structure of a high-K positive-parity band are predicted to exist near the yrast region. Our study reveals a soft nature for the ground state of N ≈ 40 isotopes and emphasizes the important role of the neutron g 9/2 orbital in determining the structure properties for both low-and high-spin states in these nuclei.

β-decay measurements forN>40Mn nuclei and inference of collectivity for neutron-rich Fe isotopes

“…These conclusions are of broad relevance especially for the neutron-rich Cr isotopes as emphasized in a recent paper [13] and consistent with shell-model calculations [17,29,51].…”

“…It is gratifying that this conclusion matches that in [17] where another microscopic model description based on a Projected Shell-Model (PSM) was employed. Actually the two models rely upon different physical pictures.…”

“…The same effect is observed in the neutron single-particle level diagram calculated for 64 Ni [16]. The energy of the 2 offered in previous shell-model studies [17].…”

“…As the collective picture stemming from our calculations is close to that provided in Ref. [17], we make a brief discussion intended to explain why both models lead to similar conclusions. Next presented are complementary calculations that are performed to estimate mean occupancies of the νg 9/2 and νd 5/2 neutron orbitals and delineate their evolution throughout the isotopic chain.…”

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

“…Thus, there appears to be a discrepancy between the TPSM and SSM results for the transition probabilities and it is highly desirable to perform the lifetime measurements for the high-spin states in 76 Ge. As quadrupole transition probabilities measure the collective behavior of a system, a correct description of it usually requires a sufficiently large model space [29].…”