The spdf IBA analytical description of odd parity states in the actinide region

An extension of the IBA 1/Lambda asymptotic scheme to the description of od d parity states via the introduction of odd / bosons in the condensate is p resented. The new Features that are thereby introduced into the system are highlighted and the advantages of using such an approach are discussed. A s tandard minimization routine is used to determine the structure coefficient s for the wavefunctions of the system and to obtain a fit to the spectra an d the electromagnetic transition rates of 11 nuclei in the actinide region with a rather small number of variable parameters, namely the single-partic le energies and the multipole interaction strengths. Reasonable results are obtained and are compared to the results of exact numerical calculations a nd earlier 1/N calculations. (C) 2000 Academic Press.