High-spin states in ${}^{82}\mathrm{Rb}$ and ${}^{84}\mathrm{Rb}$ were populated in the reaction ${}^{11}\mathrm{B}{+}^{76}\mathrm{Ge}$ at beam energies of 45 and 50 MeV. $\gamma$ rays were detected with the spectrometer GASP. The level schemes of ${}^{82}\mathrm{Rb}$ and ${}^{84}\mathrm{Rb}$ were extended up to 6.0 and 7.4 MeV, respectively. Mean lifetimes of five levels in ${}^{82}\mathrm{Rb}$ and 11 levels in ${}^{84}\mathrm{Rb}$ were determined using the Doppler-shift-attenuation method. Regular magnetic dipole bands including strong $M1\mathrm{}$ and weak $E2\mathrm{}$ transitions observed in both nuclei show the characteristic features of magnetic rotation. These bands have been successfully described in the tilted-axis cranking model on the basis of the four-quasiparticle configuration $\pi \mathrm{}\left(\mathrm{fp}\right)\mathrm{}\hspace{0.5em}\pi {(g}_{9/2}^2\left)\hspace{0.5em}\nu {(g}_{9/2}\right).\mathrm{}$ The calculations reproduce the band-like properties as well as absolute $B\left(M1\mathrm{}\right)\mathrm{}$ and $B\left(E2\mathrm{}\right)\mathrm{}$ transition strengths in both nuclei, which supports the concept of magnetic rotation. Excited states in ${}^{84}\mathrm{Rb}$ were also interpreted in terms of the shell model using the model space $\pi {(0f}_{5/2}{,1p}_{3/2}{,1p}_{1/2}{,0g}_{9/2})$ $\nu {(1p}_{1/2}{,0g}_{9/2}).\mathrm{}$ The predictions for low-lying states agree in general with the experiment. Moreover, calculated states with the main configuration $\pi {(0f}_{5/2}^{-2}{1p}_{3/2}^{-1}{0g}_{9/2}^2)$ $\nu {(0g}_{9/2}^{-3})$ can be combined into $M1\mathrm{}$ sequences which reproduce roughly the experimental transition strengths. However, these sequences do not show the features of magnetic rotation such as regular level spacings and $B\left(M1\mathrm{}\right)\mathrm{}$ values which decrease with increasing rotational frequency.

• Received 5 April 2002

DOI:https://doi.org/10.1103/PhysRevC.66.024310