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.
Abstract:
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
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