Complex fragment production in 50 MeV/A (sup 197)Au + (sup 12)C, (sup 27)Al, and (sup nat)Cu reactions.

摘要

Complex fragment (Z>6) production was studied in three reverse- kinematic reactions: 50 MeV/A (sup 197)Au + (sup 12)C, (sup 27)Al, and (sup nat)Cu. Typical inclusive cross sections are shown, as well as exclusive results for 2- , 3-, and higher-fold events. Reconstructing the source velocity of these fragments and using a simple incomplete fusion model gives a reliable measure of the impact parameter and excitation energy of the reactions producing these fragments. A clear progression from peripheral (cold) events to more central (very hot) events is seen as function of source velocity. The primary production of fragments in the (sup 197)Au + (sup 12)C and (sup 27)Al reactions is consistent with statistical emission from a thermalized source, up to approximately 5 MeV/A of excitation energy. For the (sup nat)Cu target, another significant source of fragment emission is observed. 20 refs., 15 figs.