Lifetime measurement of candidate chiral doublet bands in the ${}^{103,104}\mathrm{Rh}$ isotopes with the recoil-distance Doppler-shift method in inverse kinematics

Lifetimes of chiral candidate structures in ${}^{103,104}\mathrm{Rh}$ were measured using the recoil distance Doppler-shift method. The Gammasphere detector array was used in conjunction with the Cologne plunger device. Excited states of ${}^{103,104}\mathrm{Rh}$ were populated by the ${}^{11}\mathrm{B}({}^{96}\mathrm{Zr},4n){}^{103}\mathrm{Rh}$ and ${}^{11}\mathrm{B}({}^{96}\mathrm{Zr},3n){}^{104}$Rh fusion-evaporation reactions in inverse kinematics. Three and five lifetimes of levels belonging to the proposed chiral doublet bands are measured in ${}^{103}\mathrm{Rh}$ and ${}^{104}\mathrm{Rh}$, respectively. The previously observed even-odd spin dependence of the $B(M1)/B(E2)$ values is caused by the variation in the $B(E2)$ values, whereas the $B(M1)$ values decrease as a function of spin.

Figure 1

Excitation energy (upper) and $S(I)=[E(I)-E(I-1)]/2I$ values (lower) as a function of spin for the chiral candidate bands of ${}^{103}\mathrm{Rh}$ (left) and ${}^{104}\mathrm{Rh}$ (right).

Figure 2

Background-subtracted spectra of the 234-keV peak in ${}^{103}\mathrm{Rh}$, obtained by gating on the shifted components of the 382+384-keV transition for three different target-degrader distances as seen in the rings of $\theta ={35}^{°}$ (left) and $\theta ={146}^{°}$ (right). Shifted and unshifted components are marked as (S) and (U), respectively.

Figure 3

Experimentally determined $B(E2)$ and $B(M1)$ reduced transition probabilities in the chiral candidates in ${}^{103,104}\mathrm{Rh}$. The dashed lines between the data points are drawn to guide the eye.