摘要: 近库仑位垒重离子俘获与熔合是一个典型的多位垒穿透过程。在本征道的理论框架下，多反应道的耦合会使得单个位垒分离成一系列的分立位垒。基于位垒分布的思想，我们最近发展了一个经验的耦合道（ECC）模型，并系统地研究了220个反应体系的俘获激发函数。最近，实验报道了熔合反应^46，50Ti+¹²⁴Sn俘获激发函数的测量结果。本文将简要介绍该ECC模型，并结合通用熔合函数（UFF）的约化方法，利用该模型研究熔合反应^46，50Ti+¹²⁴Sn中的耦合道效应。UFF的约化结果表明，相比于⁵⁰Ti+¹²⁴Sn，⁴⁶Ti+¹²⁴Sn的垒下俘获截面有额外的增强。ECC模型成功地再现了实验测得的俘获激发函数，并表明，⁴⁶Ti+¹²⁴Sn垒下俘获截面的额外增强来源于正Q值的中子转移效应。


The heavy-ion capture and fusion processes at energies near the Coulomb barrier can be treated as a multi-dimensional barrier penetration problem. In the eigenchannel framework, the couplings to other channels split the single potential barrier into a set of discrete barriers. Based on the concept of the barrier distribution, we have developed an empirical coupled-channel (ECC) model and performed a systematic study of capture excitation functions for 220 reaction systems. Recently, an experiment was reported in which the capture excitation functions of reactions ^46,50Ti+¹²⁴Sn were measured. In this work, we review the ECC model briefly and use this model together with the universal fusion function (UFF) prescription to study the coupled-channel effects in fusion reactions ^46,50Ti+¹²⁴Sn. The reduced fusion functions show that the sub-barrier capture cross sections of ⁴⁶Ti+¹²⁴Sn exhibit an extra enhancement as compared with those of ⁵⁰Ti+¹²⁴Sn. The results from the ECC model reproduce the experimental capture excitation functions successfully and show that this extra enhancement of the sub-barrier cross sections for ⁴⁶Ti+¹²⁴Sn can be ascribed to the positive Q value neutron transfer effect.