标题： 激发核系统的裂变路径 显示英文标题

标题： Fragmentation path of excited nuclear systems

摘要： 我们在一个随机平均场方法的框架下，研究了激发核源的碎片化路径。 我们考虑了反应$^{129}$Xe +$^{119}$Sn 在两种束流能量下：32 和 50 MeV/A，对于中心碰撞。 观察到，在压缩阶段之后，系统向稀疏配置膨胀，从中可能重新收缩或演变为泡状结构。 然后通过体积和/或表面不稳定性的发展形成碎片。 在 32 MeV/A 下这两种可能性同时存在，导致相当不同的碎片分配，而在 50 MeV/A 下所有事件中都观察到了空心结构。 通过一种与旋节分解残余物的存在完全一致的方式恢复了较大的方差。 讨论了碎片的动力学性质，并建议作为对主要碎片生成机制非常敏感的可观测量。 在 50 MeV/A 下观察到更大的径向集体流，这与实验结果一致。 显示英文摘要

摘要： We perform a study of the fragmentation path of excited nuclear sources, within the framework of a stochastic mean-field approach. We consider the reaction $^{129}$Xe + $^{119}$Sn at two beam energies: 32 and 50 MeV/A, for central collisions. It is observed that, after the compression phase the system expands towards a dilute configuration from which it may recontract or evolve into a bubble-like structure. Then fragments are formed through the development of volume and/or surface instabilities. The two possibilities co-exist at 32 MeV/A, leading to quite different fragment partitions, while at 50 MeV/A the hollow configuration is observed in all events. Large variances are recovered in a way fully consistent with the presence of spinodal decomposition remnants. Kinematical properties of fragments are discussed and suggested as observables very sensitive to the dominant fragment production mechanism. A larger radial collective flow is observed at 50 MeV/A, in agreement with experiments.