K-shell radiative electron capture with bare 60-MeV/u Kr ions channeled in a Si crystal: Experiments and simulations.
K-shell radiative electron capture with bare 60-MeV/u Kr ions channeled in a Si crystal: Experiments and simulations.
复制标题
使用 Si 晶体中引导的裸 60-MeV/u Kr 离子进行 K 壳辐射电子捕获：实验和模拟。
DOI：
10.1103/physreva.54.1404
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Vernhet
中科院分区：
文献类型：
--
作者：
Andriamonje;Chevallier;Cohen;Cué;Dauvergne;Dural;Fujimoto;Kirsch;L'Hoir;Poizat;Quéré;Remillieux;Röhl;Rothard;Rozet;Schmaus;Toulemonde;Vernhet
我们用裸入射的60.1 MeV/u氪离子在沟道条件下和对37-µm硅晶体的随机取向进行了{italK}壳层辐射电子俘获({italK}-REC)测量。每种情况下的采样电子密度都有很大的不同，这对K-REC光子峰的形状和幅度都有影响。我们对K-REC光子线进行了模拟：为此，我们利用沟道离子的连续体势模型，确定了不同束流入射条件(方向和角扩散)下在统计平衡点的碰撞参数分布。考虑了多重散射效应。在非相对论偶极近似下计算了K-REC的光子峰，假定K-REC是一个纯局域过程。采用固态电子密度方法，计算了2个{tali S}和2个{italp}硅电子与碰撞参数相关的电子动量分布(康普顿分布)。用很高的统计量测得的能谱与计算的能谱有很好的一致性，得到了以下结果：(1)对于硅芯和价电子，分别获得了从未有过的能级K}-REC产额与束入射角的关系。我们发现，核心电子对REC的贡献对于轴向排列仍然是重要的，而在文献中通常被忽略了。(Ii)电子康普顿分布随碰撞参数的变化而显著变化。(3)自由电子气模型对价电子康普顿分布的描述是一个合理的近似。(4)在绝对精度优于20%的情况下，测量了K-REC截面，其结果与非相对论偶极近似下的计算值相近。{版权所有}{1996年美国物理学会。}比
We have performed {ital K}-shell radiative electron capture ({ital K}-REC) measurements with bare 60.1-MeV/u incident krypton ions, both in channeling conditions and for random orientation of a 37-{mu}m silicon crystal. The sampled electron densities are quite different in each case, which has an influence both on the shape and on the amplitude of the {ital K}-REC photon peak. We have developed simulations of the {ital K}-REC photon lines: for this we have determined the impact parameter distribution at statistical equilibrium for various beam incidence conditions (direction and angular spread) using the continuum potential model for channeled ions. Multiple scattering effects were included. The {ital K}-REC photon peak was calculated within the nonrelativistic dipole approximation, {ital K}-REC being assumed to be a purely local process. Solid state electron densities were used, and impact parameter dependent electron momentum distributions (Compton profiles) were calculated for 2{ital s} and 2{ital p} silicon electrons. A remarkable agreement is found between the spectra measured with very high statistics, and the calculated ones, which leads to the following results: (i) The dependence of the {ital K}-REC yield on the beam incidence angle is obtained separately for silicon core and valence electrons, which was never observed before. Wemore » find that the core electron contribution to REC is still significant for axial alignment, whereas it is generally neglected in the literature. (ii) Electron Compton profiles are found to vary significantly with impact parameter. (iii) The free electron gas model represents a fair approximation for the description of valence electron Compton profiles. (iv) The {ital K}-REC cross section is measured with an absolute accuracy better than 20{percent}, and found to be close to the value calculated within the nonrelativistic dipole approximation. {copyright} {ital 1996 The American Physical Society.}« less