New high-spin structure and possible chirality in ${}^{109}\mathrm{In}$

The high-spin structure of ${}^{109}\mathrm{In}$ has been investigated with the ${}^{100}\mathrm{Mo}({}^{14}\mathrm{N}$, $5n){}^{109}\mathrm{In}$ reaction at a beam energy of 78 MeV using the in-beam $\gamma$ spectroscopic method. The level scheme of ${}^{109}\mathrm{In}$ has been modified considerably and extended by 46 new $\gamma$ rays to the highest excited state at 8.980 MeV and $J^{\pi }=(45/2^{+})$. The new level scheme consists of eight bands, six of which are identified as dipole bands. The configurations have been tentatively assigned with the help of the systematics of neighboring odd-$A$ indium isotopes and the experimental aligned angular momenta. The dipole bands are then compared with the titled axis cranking calculation in the framework of covariant density function theory. The results of theoretical calculations based on the configurations, which involve one proton hole at the $g_{9/2}$ orbital and two or four unpaired neutrons at the $g_{7/2}$, $d_{5/2}$, and $h_{11/2}$ orbitals, show that the shape of ${}^{109}\mathrm{In}$ undergoes an evolution on both $\beta$ and $\gamma$ deformations, and possible chirality is suggested in ${}^{109}\mathrm{In}$.

Figure 1

Level scheme of ${}^{109}\mathrm{In}$ proposed in the present work. The scheme in red shows the newly identified part and the transitions marked with an asterisk (${}^{*}$) are newfound.

Figure 2

$\gamma$-ray coincidence spectra with gates set on the (a) 1428 keV, (b) 674 keV, (c) 766.6 keV, and (d) 389.8 keV transitions. Insets show the higher-energy part of the spectra. The energies marked by the asterisks are newly identified $\gamma$ rays and the energies marked by C are contaminants.

Figure 3

$\gamma$-ray coincidence spectra with gates set on (a) 362.3 keV, (b) 1103 keV, (c) 493 keV, (d) 497 keV, and (e) 367.1 keV transitions. Insets show the higher-energy part of the spectra. The energies marked by the asterisks are newly identified $\gamma$ rays and the energies marked by C are contaminants.

Figure 4

$\gamma$-ray coincidence spectra with gates set on (a) 864.8 keV, (b) 469.7 keV, (c) 443.6 keV, and (d) $941.6+816.3$ keV. Insets show the lower-energy part of the spectra. The energies marked by the asterisks are newly identified $\gamma$ rays and the energies marked by C are contaminants.

Figure 5

Systematics of the observed yrast states in the odd-$A$ indium isotopes.

Figure 6

Experimental alignments as a function of rotational frequency $\hslash \omega$ for (a) bands 1–6 (b) bands 7, 8 in ${}^{109}\mathrm{In}$ and the yrast band in ${}^{108}\mathrm{Cd}$ [39], relative to a Harris parametrization of the core of $J_0=7{\hslash }^2{\mathrm{MeV}}^{-1}$ and $J_1=9{\hslash }^4{\mathrm{MeV}}^{-3}$. The value of $K$ is chosen as 8 for the dipole bands, and 0.5 for the $E2$ bands.

Figure 7

Total angular momenta as a function of the rotational frequency in configuration-fixed (lines) constrained TAC-CDFT calculations with effective interaction PC-PK1 [40] compared with the data for (a) bands 1–5 and (b) bands 2, 5, 6 in ${}^{109}\mathrm{In}$.

Figure 8

Evolutions of deformation parameters ${\beta }_2$ and $\gamma$ driven by increasing rotational frequency in the TAC-CDFT calculations for (a) Config 1, (b) Config 2, and (c) Config 3 in ${}^{109}\mathrm{In}$. The arrows indicate the increasing direction of rotational frequency.

Figure 9

Proton, neutron, and core angular-momentum vectors ($\overrightarrow{J_{\pi }}$, $\overrightarrow{J_{\nu }}$, and ${\vec{J}}_{\mathrm{core}}$) for (a) Config 1, (b) Config 2 and (c) Config 3 in ${}^{109}\mathrm{In}$ at both the minimum and the maximum rotational frequencies in the TAC-CDFT calculations.

Figure 10

Excitation energies as a function of the spin for the rotational bands in ${}^{109}\mathrm{In}$.