具有天体物理意义的较轻系统中重离子熔合的阻碍效应
Hindrance in heavy-ion fusion for lighter systems of astrophysical interest
AI总结：
本文采用基于高斯势垒分布的简单扩散势垒公式分析较轻天体物理系统的垒下重离子熔合阻碍，其结果优于复杂耦合道计算，并可用于激发函数估计与截面外推。
摘要：
重离子反应熔合中的阻碍效应出现在极端垒下能区。这一现象可以利用一个简单的扩散势垒公式进行有效分析，该公式是在假定熔合势垒高度服从高斯分布的基础上导出的。将高斯势垒分布与固定势垒下熔合截面的经典表达式进行卷积，即可得到熔合截面。熔合截面的能量依赖关系很好地描述了现有的、关于具有天体物理意义的较轻系统的垒下重离子熔合数据。利用这一简单公式，本文给出了从$^{16}$O + $^{18}$O到$^{12}$C + $^{198}$Pt的分析，所有这些体系的测量都低至小于10 μb。本分析与测量值的符合程度甚至优于由复杂的耦合道计算所得的结果。该公式三个参数相对平滑的变化意味着，它可用于估计激发函数，或外推尚未测量的相互作用核对的截面。文中还讨论了本方法可能的扩展及其局限性。
英文摘要：
The hindrance in fusion of heavy-ion reactions crops up in the region of extreme sub-barrier energies. This phenomenon can be effectively analyzed using a simple diffused barrier formula derived assuming a Gaussian distribution of fusion barrier heights. Folding the Gaussian barrier distribution with the classical expression for the fusion cross section for a fixed barrier, the fusion cross section is obtained. The energy dependence of the fusion cross section provides good description to the existing data on sub-barrier heavy-ion fusion for lighter systems of astrophysical interest. Using this simple formula, an analysis has been presented from $^{16}$O + $^{18}$O to $^{12}$C + $^{198}$Pt, all of which were measured down to $<$ 10 $μ$b. The agreement of the present analysis with the measured values is better than those calculated even from the sophisticated coupled channels calculations. The relatively smooth variation of the three parameters of this formula implies that it may be exploited to estimate the excitation function or to extrapolate cross sections for pairs of interacting nuclei which are yet to be measured. Possible extensions of the present methodology and its limitations have also been discussed.
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