Microscopic investigation of $γ~$ vibrational band structures in odd-mass nuclei

Abstract

A systematic investigation of the high-spin band structures observed in $^{103,105,107,109}$Nb and $^{103,105,107,109}$Tc nuclides is performed using the triaxial projected shell model (TPSM) approach. For $^{103,105}$Nb isotopes, four bands have been populated with the lowest three bands corresponding to yrast, $γ$ and 2$γ$ bands. The nature of the fourth observed band has remained unresolved as it has been shown from the transition intensity ratios that this band cannot correspond to the expected 3$γ$ band. It is demonstrated in the present work that this fourth band is the second $γ$ band, resulting from the combination, $K=K_0-2$ with $K_0$ being the "$K$" value of the parent configuration. The excitation energy and other properties of this band structure are predicted for all the studied nuclides.

Figures (9)

• Figure 1: (Color online) Projected energies are shown before diagonalization of the shell model Hamiltonian for $^{105}$Nb. The bands are labelled by three quantities : $K$-quantum number, energy and group structure of the quasiparticle state. For instance, $(1/2, 0.98, 1\pi)$ designates one-quasiproton state having intrinsic energy of 0.98 MeV and K$=1/2$.
• Figure 2: (Color online) TPSM energies for the lowest five bands after configuration mixing are plotted along with the available experimental data for $^{105}$Nb isotope. Data are taken from Li054311.
• Figure 3: (Color online) Probabilities of various projected $K$ configurations in the orthonormal basis of $^{105}$Nb. The curves are labelled by three quantities: $K$ quantum number, energy of the quasiparticle state and quasiparticle character. For instance, [1/2, 0.98, 1$\pi$] designates one quasiproton state with $K$= 1/2 having intrinsic energy of 0.98 MeV.
• Figure 4: (Color online) TPSM and experimental energies of the Yrast, $\gamma_1$, $2\gamma$, $\gamma_2$ and $3\gamma$ bands of $^{103,105,107,109}$Nb isotopes. The scaling factor, $\kappa=32.32A^{-5/3}$.
• Figure 5: (Color online) TPSM and experimental energies of the Yrast, $\gamma_1$, $2\gamma$, $\gamma_2$ and $3\gamma$ bands of $^{103,105,107,109}$Tc isotopes. The scaling factor, $\kappa=32.32A^{-5/3}$.