Magnetic dipole sequences in 83Rb

High-spin states in 83Rb were populated in the reaction 11B + 76Ge at beam energies of 45 and 50 MeV. Gamma rays were detected with the spectrometer GASP. The level scheme of 83Rb was extended up to 13.9 MeV. Mean lifetimes of 23 levels were determined using the Doppler-shift-attenuation method. Among the bands newly established is a sequence including intense M1 transitions and cross-over E2 transitions. This sequence turns out to be irregular and thus shows that magnetic rotation observed in the neighboring odd-odd isotopes cannot be sustained in this odd-even nuclide. Excited states in 83Rb were interpreted in terms of the shell model using the model space pi (0f5/2, 1p3/2, 1p1/2, 0g9/2) nu (1p1/2, 0g9/2). The configuration predicted for the M1 sequence is analogous to the one predicted for the M1 band in the neighbor 84Rb and reproduces the transition strengths at high spin.