Candidate chiral doublet bands in the odd-odd nucleus ${}^{126}\mathrm{Cs}$

The candidate chiral doublet bands recently observed in ${}^{126}\mathrm{Cs}$ have been extended to higher spins, several new linking transitions between the two partner members of the chiral doublet bands are observed, and γ-intensities related to the chiral doublet bands are presented by analyzing the $\gamma$-$\gamma$ coincidence data collected earlier at the NORDBALL through the ${}^{116}\mathrm{Cd}$(${}^{14}\mathrm{N}$, $4n$)${}^{126}\mathrm{Cs}$ reaction at a beam energy of 65 MeV. The intraband $B(M1)/B(E2)$ and interband $B(M1){}_{\mathrm{in}}/B(M1){}_{\mathrm{out}}$ ratios and the energy staggering parameter, S(I), have been deduced for these doublet bands. The results are found to be consistent with the chiral interpretation for the two structures. Furthermore, the observation of chiral doublet bands in ${}^{126}\mathrm{Cs}$ together with those in ${}^{124}\mathrm{Cs}$, ${}^{128}\mathrm{Cs}$, ${}^{130}\mathrm{Cs}$, and ${}^{132}\mathrm{Cs}$ also indicates that the chiral conditions do not change rapidly with decreasing neutron number in these odd-odd Cesium isotopes.

Figure 1

Partial level scheme of ${}^{126}\mathrm{Cs}$. New transitions observed in the present work are indicated with a star.

Figure 2

Sample γ-ray coincidence spectra of the chiral doublet bands in ${}^{126}\mathrm{Cs}$. Y, S, and L stands for transitions in the yrast band, the side band, and the linking transitions between the two bands, respectively.

Figure 3

Rotational alignments of bands in ${}^{126}\mathrm{Cs}$. Harris parameters ($J_0=17.0$, $J_1=25.8$) [15] were used to subtract the angular momentum of the core.

Figure 4

Excitation energy vs. spin (upper panel) and S(I) values vs. spin for the doublet bands in ${}^{126}\mathrm{Cs}$.

Figure 5

$B(M1)/B(E2)$ and $B(M1){}_{\mathrm{in}}/B(M1){}_{\mathrm{out}}$ versus spin for yrast and side bands in ${}^{126}\mathrm{Cs}$ to compare with those in ${}^{124}\mathrm{Cs}$ [8], ${}^{128}\mathrm{Cs}$ [6], ${}^{130}\mathrm{Cs}$ [7], ${}^{132}\mathrm{Cs}$ [4]. Points with up (down) arrows represent lower (upper) limits.