Theory of Atomic Collisions

这项研究将探索强相互作用的原子系统，以开发实用的计算方案来处理它们。将开展五个项目：(1)强相互作用原子和离子的微扰级数。为强相互作用体系发展的新微扰级数将正式扩展到电离处理，并应用于计算高电离原子与低Z靶的相互作用截面。这项工作和量子电动力学的一些联系最近已经被发现，预计它们将被进一步探索。2.新的含时变分原理。一种类似于时间无关问题的Schwinger原理的新的含时变分原理将被应用到第一部分的一些问题中。变分公式的优点是能够推导出高电离体系的强势Born计算中所用的畸变势的更高阶近似。3.超球面展开。作为对“平移因子自由”理论的检验，早先发展的超球展开将应用于H+在重氢上的散射。我们将特别关注电子转移反应。剩下的就是使用计算的波函数和势能曲线进行实际的耦合通道计算。4.二次电子光谱中的鞍点效应。关于二次电子光谱中的鞍点效应的工作将继续进行。我们将建立包含旋转效应的电子传播子的新近似，并且新的传播子将被用于计算终态的近似波函数。主要的困难是多重积分的数值计算，但这似乎相当容易。这与内布拉斯加州和田纳西州的实验工作密切相关。5.阿布拉莫夫模型中的排列和定向。对准和定向参数是碰撞近似的一种非常敏感的测试。Abromov模型被用来计算低速下电子俘获形成的态的这些参数。该模型将针对现有的实验进行应用和测试。希望能刺激进一步的测量。与堪萨斯州橡树岭的实验小组以及康奈尔大学等其他高电荷电离源有着密切的合作。

This research will probe strongly interacting atomic systems to develop practical computational schemes for treating them. There are five projects to be undertaken: (1.) Perturbation Series of Strongly Interacting Atoms and Ions. The new perturbation series developed for strongly interacting systems will be formally extended to treat ionization and applied to compute cross sections for the interaction of highly ionized atoms with low Z targets. Some connections of this work and QED have recently been discovered and it is expected they will be explored further. 2. New Time Dependent Variational Principle. A new time dependent variational principle akin to the Schwinger principle for time independent problems will be applied to some of the problems of part 1. The advantage of the variational formulation is to be able to derive higher order approxi- mations to the distorting potential used in the strong potential Born calculations for highly ionized systems. 3. Hyperspherical Expansions. The hyperspherical expansion developed earlier will be applied to the scattering of H+ on deuterium as a test of the "translation factor free" theory. Particular attention will be paid to electron transfer reactions. All that remains is the actual coupled channel calculation using the computed wave functions and potential curves. 4. Saddle Point Effects In Secondary Electron Spectra. Work on saddle point effects in secondary electron spectra will be continued. New approximations to the electron propagator will be developed which contain rotational effects and the new propagator will be used to compute an approximate wave function for the final state. The primary difficulty is the numerical evaluation of the multiple integrals but this seems quite tractable. There are close connections with experimental work at Nebraska and Tennessee. 5. Alignment and Orientation in the Abramov Model. Alignment and orientation parameters are a very sensitive test of collisional approximations. The Abromov model has been developed to compute these parameters for states formed by electron capture at low velocities. The model will be applied and tested against existing experiment. The hope is to stimulate further measurements. There is close co-operation with the experimental groups at Oak Ridge, Kansas State, and other highly charged ion sources such as that at Cornell.