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Tilted-axis-cranking covariant density functional theory for the high-spin spectroscopy in $^{69}$Ga

Y. P. Wang, Y. K. Wang, P. W. Zhao

TL;DR

This work uses tilted-axis-cranking covariant density functional theory (TAC-CDFT) to interpret the newly observed positive-parity bands SI, SII, and SIII in 69Ga. It combines a rotating-frame Kohn-Sham approach with shell-model-like pairing (SLAP) to preserve particle number, identifying g9/2-dominated configurations as the basis for the bands. The study finds that pairing is crucial for accurately describing the low-spin states of SI, while SII and SIII emerge as signature partners with significant g9/2 proton and neutron alignments; predicted B(E2) values provide observables for future experiments. Overall, the work delivers a microscopic, parameter-light explanation of the high-spin structure in this odd-mass Ga isotope and guides future measurements of transition probabilities and lifetimes.

Abstract

The tilted-axis-cranking covariant density functional theory is applied to investigate the three newly-observed positive-parity bands SI, SII, and SIII in $^{69}$Ga. The energy spectra and angular momenta are calculated and compared with the experimental data. For the yrast band SI, pairing correlations play a crucial role for the states with spin $I\leq 23/2\hbar$. The bands SII and SIII are suggested to be signature partner bands with positive and negative signatures, respectively. The transition probabilities $B(E2)$ for these bands are predicted, and await further experimental verification. By analyzing the angular momentum alignments microscopicly, it is revealed that the $g_{9/2}$ protons and neutrons play an important role in the description of the collective structure of $^{69}$Ga.

Tilted-axis-cranking covariant density functional theory for the high-spin spectroscopy in $^{69}$Ga

TL;DR

This work uses tilted-axis-cranking covariant density functional theory (TAC-CDFT) to interpret the newly observed positive-parity bands SI, SII, and SIII in 69Ga. It combines a rotating-frame Kohn-Sham approach with shell-model-like pairing (SLAP) to preserve particle number, identifying g9/2-dominated configurations as the basis for the bands. The study finds that pairing is crucial for accurately describing the low-spin states of SI, while SII and SIII emerge as signature partners with significant g9/2 proton and neutron alignments; predicted B(E2) values provide observables for future experiments. Overall, the work delivers a microscopic, parameter-light explanation of the high-spin structure in this odd-mass Ga isotope and guides future measurements of transition probabilities and lifetimes.

Abstract

The tilted-axis-cranking covariant density functional theory is applied to investigate the three newly-observed positive-parity bands SI, SII, and SIII in Ga. The energy spectra and angular momenta are calculated and compared with the experimental data. For the yrast band SI, pairing correlations play a crucial role for the states with spin . The bands SII and SIII are suggested to be signature partner bands with positive and negative signatures, respectively. The transition probabilities for these bands are predicted, and await further experimental verification. By analyzing the angular momentum alignments microscopicly, it is revealed that the protons and neutrons play an important role in the description of the collective structure of Ga.
Paper Structure (4 sections, 1 equation, 4 figures, 1 table)

This paper contains 4 sections, 1 equation, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Theoretical Framework
  3. Results and discussions
  4. summary

Figures (4)

  • Figure 1: Calculated rotational energy (upper panel) and rotational frequency (lower panel) as functions of the angular momenta for the positive-parity band SI in $^{69}$Ga with and without pairing, in comparison with the data Idoko2025.
  • Figure 2: Calculated rotational energy (upper panel) and rotational frequency (lower panel) as functions of the angular momenta for the positive-parity bands SII and SIII in $^{69}$Ga, in comparison with the data Idoko2025.
  • Figure 3: Angular momentum alignments of the proton and neutron particles in the $g_{9/2}$ shell for the bands SI (a), SII (b) and SIII (c), calculated by the TAC-CDFT without the pairing correlations. The numbers below the abscissa denote the rotational frequency at which the plotted alignments have been obtained.
  • Figure 4: Calculated $B(E2)$ values as functions of the angular momenta for the positive-parity bands (a) SI, as well as (b) SII and SIII.