Theoretical study of electronic transitions in relativistic heavy-ion collisions

从Toshima等人的研究可知，非相对论耦合通道方法不需要特别考虑库仑相互作用的长程效应。我们已经证明，这不是相对论离子-原子碰撞的情况，即使对于耦合通道方法，也必须使用扭曲波形式，才能使跃迁矩阵定义得很好。基于扭曲波方法的数值计算表明，U^&lt；92+&gt；+U^&lt；91+&gt；系统的截面因此而变化了两倍以上。对称映象近似是传统映象理论的对称化形式，由于公式的简单性而得到广泛应用。我们从解析计算和数值计算中都指出，对称的程控公式不满足正确的库仑边界条件，并且由于这一缺陷，它给出了超大的自旋翻转截面。众所周知，第二个或…对于电子俘获过程，在高能时，更多的DER贡献成为主导。结果，微分截面在一个临界角出现一个尖峰，这个峰被称为托马斯峰。虽然二阶项的优势暗示了微扰理论本身的不足，但所有关于Thomas机制的理论研究都是基于微扰理论。我们开发了一种新的基于高斯型轨道展开的耦合信道码，并首次用非微扰方法成功地产生了Thomas峰。研究表明，由于多次散射效应，Thomas峰向较小的散射角方向移动，三级过程起着重要的作用。此外，我们对Thomas机制进行了经典轨道蒙特卡罗计算，结果表明，在纯经典处理中，Thomas峰意外地消失了。首次实现了重排碰撞到激发态的第二生项的精确计算，并报道了破坏性和建设性干涉效应。较少

It is known from the study of Toshima and others that special account of the long-range of Coulomb interactions is not needed in the non-relativistic coupled-channel approach. We have shown that this is not the case for relativistic ion-atom collisions and distorted-wave formalism must be used even for coupled-channel method in order to make the transition matrix well-defined. It was demonstrated by numerical calculations based on the distorted-wave method that the cross sections for the system U^<92+>+U^<91+> change more than a factor of two by this effect. The symmetric eikonal approximation, which is a symmetrized version of the traditional eikonal theory, has been used widely because of the simplicity of the formula. We pointed out from both analytic and numerical calculations that the symmetric eikonal formula does not satisfy the correct coulomb boundary conditions and it gives unphysically large spin-flip cross sections owing to this defect. It is widely known that the second-or … More der contribution becomes dominant at high energies for electron capture processes. As a result the differential cross section shows a sharp peak at a critical angle and this peak is called the Thomas peak. Although the dominance of the second-order term implies the inadequacy of the perturbation theory itself, all of the theoretical studies for the Thomas mechanism were based on the perturbation theory. We developed a new coupled-channel code based on Gauss-type orbital expansion and succeeded in producing the Thomas peak by nonperturbative method for the first time. By this study it was demonstrated that the Thomas peak is shifted to smaller scattering angle side and a third-order process is contributing significantly owing to a multiscattering effect. Besides we carried out the classical trajectory Monte Carlo calculation for the Thomas mechanism and showed that the Thomas peak is unexpectedly missing in the pure classical treatment. Exact calculation of the second-Born terms was also realized for the first time for rearrangement collisions into exited states and destructive and constructive interference effects were reported. Less