用背角准弹散射研究近库仑势垒能区重离子核反应

Study of Heavy-ion Reaction at Energy near Coulomb-barrier by Backward Quasi-elastic Scattering

利用背角准弹散射的方法开展了近库仑势垒(近垒)能区重离子核反应机制的研究。高精度测量了深垒下能区16O+152,154Sm、184W、196Pt和208Pb等体系的背角准弹散射激发函数,用耦合道计算抽取了核势的表面弥散参数,结果表明考虑耦合道效应得到的表面弥散参数值正常。基于背角准弹散射势垒分布对核结构的敏感性,尝试用深垒下能区16O+152Sm、170Er和174Yb等体系的背角准弹散射来抽取形变靶核的十六极形变参数,所抽取值与已有结果趋势一致,说明了该方法的可行性。此外,研究了弱束缚核体系的破裂效应,其表现为背角准弹势垒分布较全熔合势垒分布向低能移动,所得结果进一步说明势垒分布同时含有核结构和核反应机制的信息。

Nuclear reactions with heavy-ions at energies near the Coulomb-barrier were studied by the backward quasi-elastic scattering (QEL) method.The QEL excitation functions of 16 O + 152,154 Sm,184 W,196 Pt,and 208 Pb were measured with high precision to extract the surface diffuseness parameters of the nuclear potential.It is shown that the surface diffuseness parameters become normal when the coupled-channels (CC) effects are taken into account.Based on the sensitivity of the barrier distribution on nuclear structure,the hexadecapole deformation parameters of target nuclei were tentatively extracted from the backward QEL excitation functions of 16 O + 152 Sm,170 Er,and 174 Yb.The extracted values are consistent with the available tendency,indicating the feasibility of this method.Moreover,the breakup effects of the weakly-bound system of 9Be + 208 Pb were studied.Results show that the QEL barrier distribution was shifted to the lower-energy side comparing with the fusion one.Above results further show that the barrier distribution not only contains the information of nuclear structure but also reflects the reaction mechanism.