Binary and ternary breakup of excited projectile-like fragments produced in collisions of xenon-124,136 nuclei with tin-112,124 targets at E/A = 50 MeV.

摘要

The simultaneous measurement of neutrons and charged particles produced in peripheral and mid-peripheral collisions in a heavy-ion cross-bombardment reaction at intermediate energy, 124,136Xe + 112,124 Sn at E/A = 50 MeV, was performed at the Grand Accelerateur National d'Ions Lourds facility in Caen, France. The charged-particle and neutron detectors used in this measurement, and their subsequent calibration, is described. Analysis of dynamical decay, a common feature of such reactions, has allowed an extraction of the decay timescale as a function of the charge-asymmetry; the correlation between the composition of the lighter fragment, the size of the lighter fragment and the decay orientation is examined. Size-symmetric ternary decay of the excited projectile-like fragment is observed and characterized; the size correlation and the composition of the ternary fragments are compared to statistical model calculations. Analysis of resonant decay of the first excited state of 8Be produced in peripheral and mid-peripheral collisions of 114Cd + 92Mo at E/A = 50 MeV shows a dependence of the relative energy of the two alpha particles on the alignment of their decay. This phenomenon is interpreted in terms of Coulomb and nuclear tidal forces acting on the decaying 8Be* as well as a modification of the lifetime of the 8Be* through its interaction with the diffuse surface of the nucleus that emitted it.