EXCLUSIVE MULTIDETECTION AND STUDY OF PROJECTILE BREAKUP AT 25 AND 35A MEV IN MG-24-197(AU)

The breakup of the projectile Mg-24, excited in peripheral collisions on a gold target, has been investigated at 25 and 35A MeV with a large scintillation-detector array allowing exclusive measurements. Absolut e breakup cross sections were deduced and the projectile-like nucleus velocity and excitation energy have been reconstructed. The excitation energy partition between the projectile and the target is found to la y between the limits of equal excitation energy sharing and equal temp erature with some evolution from one limit to the other. The statistic al nature of the decay mechanism is inferred from global variables. Sm all-relative-angle analysis is applied to the six-alpha exit channel a nd the corresponding data were found to be consistent with a sequentia l evaporation decay mechanism, with some contribution from sequential fission at higher excitation energies. The time scale involved in the breakup of Mg-24 projectiles into the 6 alpha and the 5 alpha HH chann els has been investigated by examining distortions in the fragment vel ocity distributions due to the Coulomb field of the target. A decrease in the quasi-projectile Lifetime is observed as the mean excitation e nergy increases from 3.4 to 4.5A MeV.