NUCLEAR INTRINSIC VORTICITY AND ITS COUPLING TO GLOBAL ROTATIONS

Important collective modes which are generally neglected within curren t descriptions of nuclear excitations in terms of fluid dynamics, are studied here. The intrinsic vortical modes are defined in a general wa y from which a specific mode, both simple and versatile enough, is par ticularly discussed. In this paper the main emphasis is made on the co upling of the chosen intrinsic mode to the rotation of the nuclear pri ncipal axes frame with respect to the laboratory system. A semi-quanta l description of such excitations is proposed which is a generalizatio n of the so-called routhian approach of global rotations. The results of a semiclassical treatment of the corresponding variational problem are presented. A simple mean field approach where the one-body potenti al is mocked up by a harmonic oscillator is discussed in a somewhat de tailed fashion. The broad range of validity of a quadratic approximati on for the collective energy in terms of the relevant angular velociti es, is hinted from the previous simple model approach. Some general co nsequences of the latter are then drawn which have bearing on some pos sible fingerprints for the existence of such excitations, as the stagg ering phenomenon observed in gamma transition energies in some superde formed states and the occurrence of identical rotational bands in neig hbouring nuclei. (C) 1997 Elsevier Science B.V.