Study of the 40 and 60 MeV/A 129Xe + 27Al, natCu, 89Y, 165Ho and 197Au reactions: Reaction mechanism and search for exotic shapes

Multifragment disintegration of highly excited nuclear systems is currently the subject of much investigation, partly motivated by prediction of exotic nuclear shapes formed in intermediate energy collisions. Detectors with nearly 4π solid angle coverage enable complete characterization of reaction events. Present experiment utilized a combination of the MSU Miniball with the LBL forward array, together covering 87% of 4π. Reactions studied were 129Xe + 27Al, natCu, 89Y, 165Ho and 197Au at 40 and 60 MeV/nucleon. Multiplicities of light-charged particles and intermediate-mass fragments, total event mass, charge and energy were measured on an event-by-event basis. For all targets, the authors found copious production of projectile-like fragments with velocities close to the beam velocity. For heavier targets (Au, Ho and Y), the size of the fragments decreases with increasing multiplicity. for lighter targets (Al and Cu) fragments of all sizes coexist within the same multiplicity range. Event-shape analysis was applied to the most central collisions to determine the shape of the hot nuclear system