Theoretical study of the scattering of unstable nuclei and the synthesis of superheavy elements

本研究项目旨在探索不稳定核，特别是晕核引起的重离子碰撞特性，寻找合成超重元素的新途径。不稳定核的结构和多维系统中的量子隧穿也作为密切相关的学科被研究。取得的主要成果如下。1.研究了抛射Berak-up对晕核引起的重离子聚变反应的影响，结果表明，在低于库仑势垒的能量下，人们仍然可以预期晕核的聚变截面比其他同位素更大，尽管在我们以前的一篇论文中提出的晕核碰撞的聚变截面的大的增强是温和的。2.我们发现，如果使用晕核作为入射粒子，中能重离子碰撞中弹性散射的微分截面在所谓的远侧分量占主导地位的角度有一个更陡峭的下降。3.基于输运理论研究了深部非弹性重离子碰撞中的多核子转移核反应，发现在晕核作为入射粒子的情况下，交换的中子比质子多得多。4.通过对反应机制的反映，我们发现中能重离子碰撞中的弹丸碎片的横向动量分布变窄。5.研究了环境对宏观变量隧穿速率的影响，并指出在环境比隧穿过程的时间尺度略短的情况下，质量重整化的重要性。此外，我们还发展了一种处理宏观量子隧道中非绝热效应的方法--动力范数因子法，并通过几个模型计算验证了该方法的数值精度。利用这种方法，我们分析了^&lt；234&gt；U的裂变，并证明了它与核内含子的耦合

This research project aimed at exploring characteristics of heavy-ion collisions induced by unstable nuclei, especially by halo nuclei, and at finding a new way to synthesize superheavy elements. The structure of unstable nuclei and quantum tunneling in multi-dimensional systems were also studied as closely related subjects. The main achievements are as follows. 1. We studied the effect of projectile berak-up on the heavy-ion fusion reactions induced by a halo nucleus, and showed that one can still expect a larger fusion cross section for a halo nucleus than for the other isotopes at energies below the Coulomb barrier, though the projectile break-up moderates the large enhancement of the fusion cross section suggested in one of our previous papers for the collisions of a halo nucleus. 2. We showed that the differential cross section of the elastic scattering in medium energy heavy-ion collisions has a steeper fall off at angles where the so called far-side component dominates if a halo nucleus is used as the projectile. 3. We studied multi-nucleon transfer neactions in deep inelastic heavy-ion collisions based on a transport theory, and found that much larger number of neutrons are exchanged than protons if a halo nucleus is used as the projectile. 4. We showed that the tranverse momentum distribution of the projectile fragments in medium energy heavy-ion collisions gets narrower by reflectiong the reaction mechanism. 5. We studied the effects of environments on the tunneling rate of a macroscoic variable, and showed the importahce of a mass renormalization in the cases, where the environments have slightly shorter time scale than that of the tunneling process. Also, we developed a method, the method of dynamical norm factor, to treat non adiabatic effects in macroscopic quantum tunneling, and demonstrated its numerical accuracy by a few model calculations. Using this method, we analyzed the fission of ^<234>U, and showed that the coupling to a nuclear intrins