Procedure for Computing Cross Sections for Single and Multiple Ionization of Atoms in the Binary-Encounter Approximation by the Impact of Heavy Charged Particles
Procedure for Computing Cross Sections for Single and Multiple Ionization of Atoms in the Binary-Encounter Approximation by the Impact of Heavy Charged Particles
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DOI：
10.1103/physreva.8.1374
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发表时间：
1973-09
影响因子：
2.9
通讯作者：
J. Mcguire;P. Richard
中科院分区：
文献类型：
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作者：
J. Mcguire;P. Richard
开发了一种程序，用于计算质子或其他完全剥离的原子核撞击造成的原子多次电离的横截面。电离概率是能量和碰撞参数 P (E, b) 的函数，是在二元相遇近似中的几个射束能量下计算的，用于被入射质子散射的基态氢电子。给出的缩放定律可用于将这些结果扩展到其他射弹、其他目标和其他类氢填充原子壳。结果表明，对于各向同性但任意的电子密度分布，P (E, O)=< σ (E, r) 2 π r 2> 。假设电子和壳层相互独立，根据每个原子壳层的单电子概率 P (E, b) 开发了多电离截面的公式。将数值计算与半经典库仑近似的最新预测以及最近的卫星和超卫星 X 射线数据进行比较。当电离概率远小于 1 时，这些差异通常在单电离截面中 30-200% 的不确定性造成的范围内。然后，将 P (Eb) vs b 近似为阶跃函数，将多电离截面简化为单电离截面的简单组合。这些单电离截面可以通过将比例定律应用于我们制表的常用通用曲线来在二元相遇近似中进行评估。因此可以在不借助计算机的情况下估计多重电离截面。
A procedure is developed for computing cross sections for the multiple ionization of atoms by the impact of protons or other fully stripped nuclei. The ionization probability, as a function of energy and impact parameter, P (E, b), is computed at several beam energies in the binary-encounter approximation for a ground-state hydrogenic electron scattered by an incident proton. Scaling laws are given which may be used to extend these results to other projectiles, other targets, and other hydrogenlike filled atomic shells. It is shown that P (E, O)=< σ (E, r) 2 π r 2> for isotropic, but otherwise arbitrary, electron-density distributions. A formulation for multiple-ionization cross sections is developed in terms of the single-electron probabilities P (E, b) for each atomic shell, assuming that both the electrons and the shells are mutually independent. Numerical calculations are compared to recent predictions in the semiclassical Coulomb approximation and to recent satellite and hypersatellite x-ray data. The discrepancies are generally within those resulting from uncertainties of 30-200% in the single-ionization cross sections, when the ionization probability is much less than one. Then, approximating P (Eb) vs b as a step function, the multiple-ionization cross sections are reduced to simple combinations of single-ionization cross sections. These single-ionization cross sections may be evaluated in the binary-encounter approximation by applying scaling laws to the usual universal curve that we tabulate. Multiple-ionization cross sections may thus be estimated without the aid of a computer.