Microscopic investigation of magnetic and antimagnetic rotational motion in atomic nuclei

TL;DR

The paper addresses the microscopic description of magnetic and antimagnetic rotational bands in nuclei near closed shells, focusing on Pd and Cd isotopes in the A~110 region. It advances the projected shell model by incorporating quasiparticle excitations from two major oscillator shells and expanding to five-quasiparticle configurations in odd-mass systems, enabling detailed predictions of excitation energies, alignments, and electromagnetic transitions. The results show that the extended PSM reasonably reproduces MR/AMR spectra, bandcrossings, and BE2/BM1 trends, and align well with semiclassical SCM insights while revealing the role of deformation and multi-qp mixing in high-spin behavior. This microscopic framework enhances understanding of MR/AMR phenomena and opens routes to exploring positive-parity bands and related regions such as Pb.

Abstract

In the present work, we have generalized the projected shell model (PSM) approach to include the quasiparticle excitations from two major oscillator shells, and have also extended the basis space to five-quasiparticle configurations for odd-mass nuclei. The magnetic and antimagnetic rotational structures observed in odd-neutron Pd- and Cd-isotopes have been investigated as a first major application of the new development. It is shown that PSM approach provides a reasonable description of the observed properties of magnetic and antimagnetic rotational bands.

Figures (17)

• Figure 1: Schematic illustration of the twin-shears mechanism leading to the formation of an antimagnetic rotational band.
• Figure 2: (Color online) Comparison of PSM calculated energies after configuration mixing with the corresponding available experimental data 101pdsuga2 for $^{101}$Pd.
• Figure 3: (Color online) Angular-momentum projected energies are shown before diagonalization of the shell model Hamiltonian for $^{101}$Pd.
• Figure 4: (Color online) Comparison of PSM calculated energies after configuration mixing with the corresponding available experimental data 103pdamrCd94109pd for $^{103,107-111}$Pd.
• Figure 5: (Color online) Angular-momentum projected energies are shown before diagonalization of the shell model Hamiltonian for $^{103,107-111}$Pd.