Fusion Enhancement in the 38S+208Pb Reaction

Abstract

The capture-fission cross section was measured for the reaction of 38S with 208Pb for center-of-mass projectile energies Ecm of 160-265 MeV. The 38S beam was prepared by projectile fragmentation at the NSCL at higher energies and degraded to 4-7 MeV/nucleon. The time of flight (energy) of each interacting beam particle was measured along with the fission fragments. The data were compared to previous measurements of the capture-fission excitation function for the 32S+208Pb reaction. The interaction barrier for the 38S-induced reaction is 16.1�10.1 MeV lower than the 32S-induced reaction whereas the reduced excitation functions for the two reactions are similar. A discussion of the systematics of barrier shifts in the fusion of n-rich nuclei is given and the implications of this shift for the synthesis of heavy nuclei with radioactive beams are discussed.