Stripping- and pickup-induced breakup in 11- and 17-MeV/nucleon 20Ne+197Au reactions.

Abstract

Breakup processes in 220- and 341-MeV /sup 20/Ne+/sup 197/Au reactions were studied by performing coincidence measurements of the secondary fragments. Projectile-like fragments and light charged particles corresponding to primary stripping, pickup, and inelastic channels were examined. The projectile-like fragments were detected near the classical grazing angle. Kinematic reconstructions of the three-body final states were used to deduce the excitations in the primary projectile-like and target-like fragments. At both bombarding energies, the stripping channels produced relatively cold ejectiles, with the excitation residing mostly in the target recoil. However, the pickup channels tended to leave the target cold, while populating higher excitations in the ejectile. The data are consistent with nucleon transfer as the dominant mode for generating excitation, with the partition of excitation energy between the fragments governed by the direction of the transfer. An extended version of the optimum-Q-value model of Siemens et al. predicts target-like excitations in good agreement with data at 11 MeV/nucleon, but with deviations occurring at 17 MeV/nucleon.