极深垒下熔合反应中扩散过程的研究

Investigation of Diffusion Process in Deep Sub-barrier Fusion Reactions

基于弹核和靶核接触后的泡利阻塞效应,引入了一个新的扩散因子来描述在极深垒下能区熔合反应中的阻碍现象。在本工作中,熔合截面假定由两部分的乘积构成:克服库仑势垒的隧穿因子和两个反应核接触后的扩散因子。前者可以由耦合道方法来描述,后者则由入射的能量和系统的温度决定。对存在阻碍现象的21个熔合体系进行了详细分析,发现扩散因子在熔合阻碍的实验阈值能量附近起到了重要的作用。此外,以负Q值熔合体系^(64)Ni+^(64)Ni和正Q值熔合体系^(24)Mg+^(30)Si为例,发现熔合截面以及两个重要表象(天体S因子和对数导数)的计算结果与实验数据具有较好的一致性。

We introduce a new diffusion factor to describe the hindrance phenomenon in fusion reactions at deep sub-barrier energies based on the Pauli blocking effect after the projectile and target overlap.In this approach,the fusion cross sections are assumed to be the product of two parts:the tunneling factor to overcome the Coulomb barrier and the diffusion factor after two colliding nuclei contact.The former is described by coupled-channels approach and the latter depends on the colliding energies as well as the temperature of system.In total,21 fusion systems with hindrance phenomenon are analyzed in details and it is found that the diffusion factor plays an important role near the experimental threshold energies of fusion hindrance.In addition,taking negative-Q-value system^(64)Ni+^(64)Ni and positive-Q-value system^(24)Mg+^(30)Si as examples,not only fusion cross sections but also two important representations,namely,astrophysical S factor and logarithmic derivative,are found to be in good agreement with experimental data.