Rotational bands in deformed nuclei

Abstract

The authors present an alternative derivation of the strong-coupling adiabatic model for nuclear rotational bands generated by coupling particles to a rotor. They avoid as far as possible the use of symmetry arguments as well as the assumption of the motion of a particle in a static deformed field. Instead they approach the problem by diagonalising a rotationally invariant Hamiltonian using basis states of good angular momentum at all stages. This leads to the standard 'symmetrised' wavefunctions in a transparent manner, with appropriate constraints on the effective mean field for the particles emerging naturally. The cranking approximation is derived in a way which leads automatically to the relation between the total angular momentum of the system and the signature of the particles in the cranked deformed field. The advantage of such an approach is that it is easier to see how to extend this model and give as an example the application to a system where the effective mean field possesses an octupole component. The origin of the parity splitting that is observed in this case is discussed, as is its dependence on odd and even particle number.