Vanadium K-shell X-ray emission induced by xenon ions at near the Bohr velocity
Vanadium K-shell X-ray emission induced by xenon ions at near the Bohr velocity
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接近玻尔速度的氙离子引起的钒 K 壳层 X 射线发射
DOI：
10.7498/aps.65.027901
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发表时间：
2016-01
影响因子：
1
通讯作者：
Zhao YT
中科院分区：
文献类型：
--
作者：
Zhou Xian-Ming;Zhao Yong-Tao;Cheng Rui;Lei Yu;Wang Yu-Yu;Ren Jie-Ru;Liu Shi-Dong;Xiao Guo-Qing;Zhou Xian-Ming;Chen Xi-Meng;Zhou Xian-Ming;Ren Jie-Ru;Liu Shi-Dong;Zhao Yong-Tao;Mei Ce-Xiang;Zhao YT;Zhao YT
测量了2.4 ~ 6.0 MeV Xe20+离子撞击钒表面时产生的x射线发射光谱。从实验产额数据中提取了V k壳层x射线产生截面，并与二元相遇近似（BEA）、平面波玻生近似（PWBA）和能量损失库仑排斥摄动稳态相对论（ECPSSR）的理论预测进行了比较。为了合理地预测高电荷重离子在接近玻尔速度的不对称碰撞中引起的内壳电离，讨论了BEA模型的修正。研究发现，在玻尔速度附近运动的高电荷重离子诱导的x射线产生截面约为1 barn数量级，比质子诱导的x射线产生截面大了近4个数量级。ECPSSR模型被认为是模拟光离子内壳电离的最佳模型，但它可能对实验数据有至少三个数量级的低估。PWBA模型对结果的预测能力比ECPSSR模型好一个数量级，但比BEA模型的预测能力差。经库仑斥力和有效核电荷修正后的BEA计算结果与实验结果最吻合。提出在玻尔速度附近的能量区，在Xe20+离子与V原子的不对称碰撞过程中，V的k壳层电子被直接电离，可以用氙离子与束缚电子的二元相遇过程来描述。x射线产生截面可以用BEA模型模拟，但必须考虑库仑斥力和有效核电荷的修正。
The X-ray emission spectra produced by 2.4-6.0 MeV Xe20+ ions impacting on vanadium surface were measured. The V K-shell X-ray production cross sections were extracted from the experimental yield data and compared with the theoretical predictions of the binary encounter approximation (BEA), the plane wave born approximation (PWBA), and the energy-loss coulomb-repulsion perturbed-stationary-state relativist (ECPSSR). In order to predict reasonably the inner-shell ionization induced by highly charged heavy ions during the asymmetric collisions at near the Bohr velocity, the corrections of BEA model are discussed. It is found that the X-ray production cross section induced by highly charged heavy ions moving at near the Bohr velocity is on the magnitude of 1 barn, which is almost four orders of magnitude larger than that induced by proton. The ECPSSR, which is regarded as the best model to simulate the inner-shell ionization by light ions, may underestimate the experimental data at least three orders of magnitude. The PWBA model presents a prediction to the results on an order of magnitude better than the ECPSSR simulation, but gives a worse tendency than the BEA model. The BEA calculations, corrected both by Coulomb repulsion and effective nuclear charge, present the best agreement with the experimental results. It is proposed, that in the energy region near the Bohr velocity, during the asymmetric collisions of Xe20+ ions with V atoms, the K-shell electron of V is ionized by direct ionization, and that it can be described by the binary encounter process between the xenon ions and the bound electrons. The X-ray production cross section can be simulated by BEA model, but the corrections of Coulomb repulsion and effective nuclear charge must be considered.