Decay of deformed and superdeformed nuclei formed in heavy ion reactions

Abstract

The importance of considering the deformation of nuclei at high angular momenta in computing transmission coefficients for their decay is the major topic of this work. Deformations based on the rotating liquid drop model were used to generate transmission coefficients versus compound nucleus angular momentum. The results were then used in a Hauser-Feshbach code which included fission competition to assess the ultimate importance of deformation modified transmission coefficients. It was found that for a broad range of prolate nuclei (superdeformed) the course of deexcitation predicted changes totally from predominant fission to predominant ..cap alpha.. decay because of a new mechanism called ..cap alpha..-decay amplification. The phase space relationships responsible for this new mechanism are presented. It is shown that this predicted new decay mode of superdeformed nuclei is consistent with a large body of existing experimental results, though more explicit experiments must be completed to confirm the new mechanism.