Multiple antimagnetic rotation bands in odd-$A$ ${}^{107}$Cd

Lifetimes of the excited states of a pair of positive-parity $\Delta I=2$ bands of ${}^{107}$Cd have been measured by using the Doppler-shift attenuation method. The obtained $B\left(E2\right)$ transition rates significantly decrease with increasing spin, a behavior typical of antimagnetic rotation (AMR). The observed results, interpreted by the semiclassical model (SCM) calculations, confirm these bands to be AMR bands resulting from the coupling of a pair of high-$\Omega$ $g_{9/2}$ proton holes to aligned $g_{7/2}{\left(h_{11/2}\right)}^2$ neutron particles. This is the first evidence for two AMR bands in a single nucleus.

Figure 1

Partial level scheme of ${}^{107}$Cd showing the positive-parity bands 5 and 6.

Figure 2

Representative spectra and the line-shape fits for the 1107-keV transition using the 1076 $+$ 686 $+$ 939 keV sum gated spectrum (left) and 1266-keV transition using the 686 $+$ 939 keV sum gated spectrum (right). The true line shape of each peak is shown by the red line. The blue line shows the total fitting after including all the contaminant peaks (shown by the green, pink, and orange lines).

Figure 3

Comparison of the measured $I\text{vs}\omega$ (a) and $B\left(E2\right)\text{vs}I$ (b) values for bands 5 and 6 with those calculated from the SCM.