Backbending in the nucleus 155Er

High spin states of the i13/2 band in 155Er have been populated using (12c, xn) reactions. Backbending-type behaviour appears, in sharp contrast with the heavier neighbouring odd erbium isotopes. The result apparently disagrees with the blocking effect of the rotation alignment model which is known to inhibit the development of the backbending mechanism. This suggests either that states other than i13/2 are involved in the 155Er backbending or that, due to strong vibrational effects, the rotation alignment model is not applicable.