Absolute El, ΔK= O Transition Rates in Odd-Mass Pm and Eu-Isotopes

The half life of the 5/2- (532) intrinsic state in 151Pm, 153Eu and 155Eu has been determined by the delayed coincidence method. The absolute E1, ΔK = 0 transition probabilities between the 5/2- (532) -> 5/2+ (413) intrinsic states have been deduced and compared with theoretical predictions, using the Nilsson model as a starting point. The effect on the predicted transition probabilities obtained by adding pairing correlations and Coriolis coupling have also been studied. It has been found that the experimental transition rates, which are still strongly enhanced, cannot be explained by these contributions alone. It is therefore suggested that collective dipole contributions like those arising through the octupole excitations are of importance