超重核^(266)Hs形成截面的入射道依赖

Entrance Channel Dependence of Production Cross Sections of Superheavy Nucleus ^(266)Hs

计算和比较了^(26)Mg+^(244)Cm,^(27)7Al+^(243)Am和^(32)S+^(238)U3个反应系统的俘获截面和复合核^(270)Hs形成截面．在俘获截面计算中,考虑了靶核形变效应．穿越库仑势垒后,反应系统由熔合谷进入不对称裂变谷．只有越过不对称裂变谷中的条件鞍点的事件才进入复合核组态．我们用考虑中子流动和径向运动的二参量Smoluchowski扩散方程来处理中间阶段的动力学过程．此外,还计算了经4n蒸发形成超重核^(266)Hs的截面．研究表明,入射道的势垒分布,中间阶段的条件鞍点高度对俘获截面,复合核形成几率,以及最终的超重核形成截面有显著影响．

For the ^26Mg＋^244Cm, ^27Al＋^243Am and ^32S＋^238u systems, the capture cross sections and the formation of the compound nucleus ^270Hs are calculated and compared. In the entrance channel, the projectile is captured after overcoming the Coulomb barrier that has a distribution due to the deformation of the target nucleus. After contact, the system is assumed to be injected into an ＂asymmetric fission valley＂ by the neutron induced neck formation. The dynamic process of the composite nucleus in the ＂asymmetric fission valley＂ is treated in a two-parameter Smoluchowski equation in which neutron flow and diffusion in elongation coordinates are taken into account. The compound nucleus configuration is achieved only for those events where the system has diffused over the conditional saddle-point in the ＂asymmetric fission valley＂. Our results show that the Coulomb barrier in the entrance channel and the height of the conditional saddle-point in the ＂asymmetric fission valley＂ have obvious influence in the processes of the capture and compound nucleus formation.