Rotation-particle coupling in the ground state band of 161Dy

Abstract

The 160Gd(α, 3n)161Dy reaction is used to populate the 5/2+ [642] ground state band in 161Dy up to the member with spin 33/2. The rotational energies within this strongly perturbed band are successfully explained within the unified model with the pairing, Coriolis and ΔN = 2 interactions included if the theoretical Coriolis matrix elements are reduced. This model can at the same time account for the relative electromagnetic transition probabilities and the static magnetic moment of the 5/2, 5/2+ [642] ground state only if the intraband M1 transition amplitudes with |Δ K| = 1 are also reduced. The same conclusion may be drawn from an analogous analysis of the 7/2+ [633] band in 167Er. These observations suggest that the longitudinal and the transverse spin polarisation is different or that the mechanism which is responsible for the reduction of the Coriolis force is also effective in preventing intra-band M1 transitions with |ΔK| = 1.