Sub-barrier fusion of neutron-rich nuclei and the role of neutron transfer and neutron-flow

Abstract

We [Collaboration members include: F.J. Liang, D. Shapira, C.J. Gross, J.R. Beene, R.L. Varner, P.E. Mueller, A. Galindo-Uribarri, J. Gomez del Campo, D.W. Stracener, Physics Division ORNL, W. Loveland Oregon State Univ., H. Amro, J.J. Kolata Univ. of Notre Dame, J. Bierman Gonzaga Univ. A. L. Caraley State Univ. of New York at Oswego] have measured the formation of Evaporation Residues (ER) at near-barrier energies in collisions between several Te and Sn beams on 58 Ni and 64 Ni targets. The measured excitation functions are sparse but by measuring several systems we try to explore systematic trends in the sub-barrier cross section for ER formation. The data obtained show the expected enhancement in ER production (survival) with the addition of neutrons to the fused system. The overall cross sections, however, depend strongly on the capture cross sections that are the focus of this presentation An analysis of nucleus-nucleus capture in this mass region is attempted in the framework of a WKB formalism that incorporates neutron transfer/flow in a two-step process. The calculated capture cross sections are compared with the new, and other available data in this mass region. We use global potentials in our analysis and do not fit individual data sets but hope that these, or similar, calculations will provide a simple base for the prediction of trends in nucleus-nucleus capture cross sections.