Evolution from the coplanar to the perpendicular plane geometry of helium (e,2e) differential cross sections symmetric in scattering angle and energy.
Evolution from the coplanar to the perpendicular plane geometry of helium (e,2e) differential cross sections symmetric in scattering angle and energy.
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散射角和能量对称的氦 (e,2e) 微分横截面从共面几何到垂直平面几何的演变。
DOI：
10.1103/physreva.47.3724
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Read
中科院分区：
文献类型：
--
作者：
Murray;Read
本文给出了氦中（[ital e],2[ital e]）过程的微分截面，其中两个出射电子相对于入射光束具有相同的能量和相同的散射角。在超过电离阈值的20 ~ 50 eV的4次入射能量下，由出射电子定义的探测平面从与入射光束共面到垂直于入射光束。微分截面由共面几何的双峰结构演变为垂直平面上的三峰结构。在最低能量下，前向散射共面峰小于后向散射峰，而在较高能量下，结果则相反。在67.5[度]的中间平面角处可见深最小值，这个最小值在电离阈值以上40 eV处最深。结果归一化到一个绝对尺度使用以前的共面测量在文本中讨论。用于采集这些结果的光谱仪是完全计算机控制和实时计算机优化的。
Experimentally determined differential cross sections are presented for the ([ital e],2[ital e]) process in helium, in which the two outgoing electrons have the same energy and the same scattering angle with respect to the incident beam. At four incident energies from 20 to 50 eV above the ionization threshold the detection plane defined by the outgoing electrons was varied from being coplanar with the incident beam to being perpendicular to the beam. The differential cross section evolves from a two-peak structure in coplanar geometry to a three-peak structure in the perpendicular plane. At the lowest energy the forward-scattering coplanar peak is smaller than the backscatter peak, in contrast to the results at higher energies. A deep minimum is seen at an intermediate plane angle of 67.5[degree], this minimum being deepest at 40 eV above the ionization threshold. The results are normalized to an absolute scale using previous coplanar measurements as discussed in the text. The spectrometer used to collect these results is fully computer controlled and real-time computer optimized.