Modelling dissipative break-up of heavy ions

Projectile break-up with two outgoing intermediate-mass fragments in 26 AMeV32S+197Au

“…2, 3) reminds of the same feature as observed in particle emission [12,19] where it was taken as qualitative manifestation of the direct break-up mode in the sense of the dynamical model [10,18] described in the next section: in a deep-peripheral collision, the target-distant part of the projectile is only slightly deflected and decelerated (and hits the trigger, in our case), while the target-close part by the strong friction force is separated from the remainder, decelerated and bent around the target nucleus in an orbiting trajectory.…”

“…therein). This qualitative identification has been corroborated by a semi-quantitative description of cross sections and correlations with the model of M6hring et al [10] which incorporates the principal dynamical features in a molecular-dynamics treatment, taking e particles as the basic projectile constituents of this dynamics. The description of two complex ejectiles (IMFs), each containing several c~ particles, as a correlation of high order is a particular challenge for and in the trigger telescope at 14.3 ~ the second in phoswich detectors within 4 ~ to 9 ~ relative angle to the first) with respect to the element numbers Z of the two fragments.…”

“…(As IMF we denote all projectile fragments with Z> 2.) The projectile chosen, 328, is sufficiently heavy to yield a variety of different IMF-IMF decay channels for a detailed comparison with theoretical predictions, and is at the same time sufficiently small to allow computations within the semi-microscopic model [10] developed for the purpose of a deeper understanding of projectile break-up processes. If successful in the present case, the model predictions for other systems and energy domains may serve as an estimate of the possible contribution of the projectile break-up mechanism.…”

Multifragmentation study on 30 AMeV32S+58Ni

“…Intervals of source velocity used in the simulations of statistical multifragmentation. The mean velocity (or linear momentum transfer, LMT) is given as fraction of the c.m.s, velocity (or projectile momentum), E* is the excitation energy, which is calculated with the model of M6hring et al [9], as well as its absolute and relative yield distribution over the intervals, a(E*) and f(E*) Nr with the acceptance of the detector set-up including the experimental mass and velocity thresholds. To improve the statistics of accepted events, the emitting-system coordinate frame was repeatedly rotated by stochastic rotation angles in order to increase the probability that the laboratory velocity vector of one of the fragments would enter the fixed-angle triggering telescope.…”

“…In particular, a given momentum transfer in the strict imcomplete-fusion picture involves a definite mass transfer and excitation energy of the primary heavy reaction product, the latter quantities being needed as input for the SMF codes. Going a step beyond the simple incomplete-fusion assumption, the correlations between the three quantities were calculated with the e particle molecular-dynamics model of M6hring et al [9] allowing for partial fusion and/or break-up of the projectile nucleus. This model was also used to provide the probability distribution over the eight intervals.…”