Perturbed alignments within an i13/2 neutron intruder band in Gd141

The nucleus Gd141 was investigated at high spins for the first time via the reactions Sn112(32S,2pn)141Gd at 155 MeV and Sn112(33S,2p2n)141Gd at 170 MeV. The methods of in-beam γ-ray spectroscopy were used to establish a number of different structures. These include a band assigned as the νi13/2[660]1/2+ intruder in the Nilsson scheme. This is the heaviest nucleus thus far in which this type of intruder band has been identified, and is the first case in which the 13/2+ bandhead has been clearly observed. Cranked shell model (CSM) calculations predict the occurrence of backbends due to h11/2 proton and h9/2 neutron band crossings. Gradual upbends are observed in the experimental alignments, which suggests the interaction strengths are stronger than those predicted by the CSM.