Dynamical effects in nuclear collisions in the Fermi energy range: aligned breakup of heavy projectiles
- 作者：Bocage ; F. ; Colin ; J. ; Louvel ; M. ; Auger ; G. ; Bacri ; Ch.O. ; Bellaize ; N. ; Borderie ; B. ; Bougault ; R. ; et. al.
- 关键词：24.75.+i ; 25.70.Mn ; 25.70.Pq ; Heavy ions reactions at intermediate energy ; Fragment correlations ; Fission and aligned breakup ; Deformation and neck instability
- 刊名：Nuclear Physics A
- 出版年：2000
- 期刊代码：44_03759474
- 类别：ph
- 出版时间：August 28, 2000
- 卷：676
- 期：1-4
- 页码：391-408
- 文件大小：840 K
摘要
Recent experimental results concerning heavy systems (Pb+Au, Pb+Ag, Pb+Al, Gd+C, Gd+U, Xe+Sn, …) obtained at GANIL with the INDRA and NAUTILUS 4π arrays will be presented. The study of reaction mechanisms has shown the dominant binary and highly dissipative character of the process. The two heavy and excited fragments produced after the first stage of the interaction can decay into various decay modes from evaporation to multifragmentation including fission. However, deviations from this simple picture have been found by analyzing angular and velocity distributions of light charged particles, and fragments. Indeed, there is a certain amount of matter in excess emitted between the two primary sources suggesting either the existence of a mid-rapidity source similar to the one observed in the relativistic regime (participants) or a strong deformation induced by the dynamics of the collision (neck instability). This last possibility has been suggested by analyzing in detail the angular distributions of the fragments. More precisely, we observe an isotropic component which is compatible with the prediction of statistical models and a second one corresponding to breakup aligned with the recoil direction of the projectile like source which should be compared with the predictions of dynamical calculations based on microscopic transport models.