Effect of deformation on the twist and other dipole modes - art. no. 054311

The dependence on deformation of the isovector twist mode ([rY(1) (l) over right arrow](lambda =2)t(+)) is investigated. We calculate the strengths an d energies in the asymptotic (oblate) limit using C-12 as an example of a s trongly deformed nucleus. We also consider the lambda = 1 case. In a DeltaN = 0 Nilsson model the summed strength is independent of the relative P-3/2 and P-1/2 occupancy but when we allow for different frequencies omega (i) in the x, y, and z directions there is an enhancement of this strength due to deformation. This dependence is stronger than that for the ordinary dipo le mode but much weaker than that for the scissors mode. At the same time, it is observed that there are considerable changes in the spectrum and that the strength is strongly fragmented amongst these disparate levels. We fur ther show that in this model the associated spin mode [rY(1)(s) over right arrow](lambda)t(+) has a weaker dependence on deformation and is less fragm ented than the twist mode.