A REEXAMINATION OF THE ABRASION-ABLATION MODEL FOR THE DESCRIPTION OF THE NUCLEAR FRAGMENTATION REACTION

The nuclear fragmentation reaction is studied as an important production mechanism for secondary beams. The geometrical abrasion model and a macroscopic evaporation model which describe the two steps of the reaction are reexamined. Several improvements and modifications of these models are discussed and a new model description incorporating these elements is proposed. In particular, the excitation energy and the angular-momentum distribution of the prefragments, the formulation of evaporation as a diffusion process and the role of microscopic structure in the production cross section are considered. The new model description preserves the simplicity and the transparency of the original models. The predictions of the new model are compared to those of the original models and to experimental cross sections. While original models showed several systematic discrepancies in comparison to measured cross sections, the new model is able to reproduce the whole body of experimental data with satisfactory agreement.