MULTIFRAGMENTATION OF SPECTATORS IN RELATIVISTIC HEAVY-ION REACTIONS

摘要

Using the ALADIN forward-spectrometer at SIS we have studied multi-fragment decays of Au-197 projectiles after collisions with C, Al, Cu and Pb targets at a bombarding energy of E/A = 600 MeV. The new data presented in this work comprise the measured cross sections of multifragment processes, the N/Z ratios of the produced fragments, and the differential distributions of fragment multiplicities and of observables built on the charge correlations within the event. The Au-197+Cu data are analyzed with the statistical multifragmentation model. It is shown that all observables can be simultaneously reproduced on an absolute scale, apart from an overall normalization constant which relates the number of model events to the measured cross section. A continuous distribution of excited residual nuclei, used as input for the calculations, was derived from the criterion of a best fit to the data. It exhibits a correlation between decreasing mass number A and increasing excitation energy E(x)/A and a saturation of the excitation energy at E(x)/A approximate to 8 MeV. [References: 22]