Heavy residue formation in 20 MeV / nucleon 197 Au + 90 Zr collisions

The yields and velocity distributions of heavy residues and fission fragments from the reaction of 20 MeV/nucleon 197Au + 90Zr have been measured using the MSU A1200 fragment separator. A bimodal distribution of residues is observed, with one group, resulting from peripheral collisions, having fragment mass numbers A= 160–200 while the other group, resulting from “hard” collisions, has A = 120–160. These “hard” collision residues can be distinguished from fission fragments by their velocities. A model combining deep-inelastic transfer and incomplete fusion for the primary interaction stage and a statistical evaporation code for the deexcitation stage has been used to describe the properties of the product distributions.  2002 Elsevier Science B.V. All rights reserved. PACS: 25.70.-z; 25.70.Jj; 25.70.Lm