Changes in shape polarisation across the odd neutron-rich Cr isotopes

Abstract: Excited states in 57Cr have been populated to high spin in the reaction at a beam energy of 130 MeV. A regular sequence of stretched quadrupole transitions has been established above the yrast level. This sequence is interpreted as a rotational band associated with prolate deformation induced by the excitation of the odd neutron into the orbital. Total Routhian surface calculations, which follow this configuration to high spin, reproduce the observed features of the band. They are also able to account for a similar, but less well developed structure in 55Cr. In contrast, the isomeric yrast state in 59Cr appears to be a band-head state dominated by the configuration, which is favoured at oblate deformations. Such a marked difference presents a significant challenge for theoretical descriptions, but is consistent with features exhibited by the low-lying negative-parity states in 59Cr. [Copyright &y& Elsevier]