Short-lived binary splits of an excited projectile-like fragment induced by transient deformation
Sylvie HUDAN (Indiana, USA)
11h , GANIL room 105
A coffee will be served 15 mn before
Aligned fragment emission associated with peripheral and midperipheral dissipative collisions of 124Xe+124Sn at E/A=50 MeV is examined. Binary decay of the excited projectile-like fragment (PLF*) is correlated with significant velocity damping from the projectile velocity. Both a forward emission component, attributed to standard statistical emission, and a backward component are observed. The backward component arises from both statistical sand dynamical decay processes. This backward component manifests a strong alignment with the direction of the PLF* velocity and is found to depend sensitively on the atomic number of the light fragment, ZL, and the velocity of the PLF*. The yield of the backward component is significantly enhanced relative to the forward component. The composition of fragments emitted in the backward direction reveals that a correlation between alignment and neutron excess exists for fragments with Z<8. From the measured asymmetry of the angular distributions, the angular distribution for dynamical fragment emission is deduced. Comparison with a schematic one-dimensional Langevin model allows extraction of both the magnitude and the dependence on ZL of the transient initial deformation of the PLF*. Fragment emission times of the order of 0.25–1.5×10-21 s are extracted.
