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1.
The probability W(x) of inner shell ionization by nuclei as a function of the impact parameter x is expressed through the ionization matrix element Mif. Values of W(x) for removal of the 2s and 2p electrons are calculated with the first Born Mif and compared with the SCA result.  相似文献   

2.
It is shown that the data of Middleman, Ford and Hofstader on K-shell ionization by electrons with energy from 150 to 900 MeV is fit very well by a relativistic form of Bethe's theory of ionization.  相似文献   

3.
Data on K-shell ionization by relativistic electron impact have been correlated for a wide range of elements (Z=13–83) and incident electron energies (E=3–900 MeV). A semi-empirical scaling law that has been developed using the Kolbenstvedt virtual photon theory is presented.  相似文献   

4.
The K2 X-rays from Be, B and O atoms by H- and He-ion bombardment were measured. The ratio of σ2K(He) to σ2K(H) exhibits the projectile Z41 dependence. This is the first observation of the Z1-dependence of σ2K predicted by the Coulomb excitation.  相似文献   

5.
The dependence on the scattering angle of the K-shell ionization probability has been measured with 0.5 MeV H+, 1 MeV D+ and 2 MeV He+ on copper targets. The experimental values are compared to SCA calculations corrected for binding, retardation and relativistic effects. The angular dependences are in good agreement with the theoretical predictions if the rapid variation of the nuclear relative velocity at the distance of closet approach is correctly taken into account (“hair-spin curve” effect).  相似文献   

6.
Despite its great sensitivity, the usefulness of secondary ion mass spectrometry (SIMS) for many applications has been limited by an inadequate understanding of the probability of sputtering an atom in an ionized state. To determine this ionization probability for clean Cu and Ni surfaces, I have measured the energy distribution of sputtered neutrals and ions by quadrupole mass filtering and retarding potential analysis using potential modulation differentiation. Analysis of sputtered neutrals was accomplished by electron impact ionization. Because the neutrals outnumber the ions by at least two orders of magnitude, the ratio of sputtered ions to neutrals is an accurate measure of the ionization probability. For energies below 20 eV the dependence of the ionization probability on energy goes as P(E) α En, where n = 0.65 for clean Cu. The absorption of oxygen on the Cu surface increases the total ion yield while causing a reduction in the value of the exponent n. Similar results are found for nickel, where n = 0.54 for the clean surface.  相似文献   

7.
8.
We evaluate the total cross section for the single K-shell ionization of atoms and ions by the impact of relativistic electrons. The study is performed to leading orders of the QED perturbation theory with respect to the parameters αZ and 1/Z. The results obtained are in good agreement with experimental data for different atomic targets. In the case of moderate values of the nuclear charge Z, the total cross section is described by a simple analytic formula. The K-shell ionization by relativistic heavy particles is also considered.  相似文献   

9.
The ratios of X-ray yields from the K-shells of gaseous 10Ne,14Si, and 18Ar by 63Li+1,2,3 and protons were measured at projectile velocities comparable to the orbital velocities of the target K-shells. Projectile charge-state dependence is accounted for quantitatively when electron capture by the projectile and screening of the projectile by its electrons are included.  相似文献   

10.
The general intensity dependence of the five-photon ionization probability of triplet metastable helium was measured.  相似文献   

11.
Relative K-shell ionization cross sections of Cl and Ca measured with 200 keV/amu singly ionized projectiles of 2H, 4He, 12C, 14N, 16O and 20Ne exhibit features which are adequately described by the combination of binding effect in Coulomb ionization and charge exchange to the empty orbitals of the projectile.  相似文献   

12.
非局域热动平衡等离子体K壳层电离平衡模型   总被引:1,自引:0,他引:1  
发展了针对非局域热动平衡等离子体的K壳层电离平衡模型.模型中详细计算了各原子过程参数,并通过求解速率方程的稳态解得到各电离态的布居分布.在此基础之上,研究了谱线强度比值对等离子体温度、密度的依赖关系.最后,我们根据此模型的计算结果,分析了在神光Ⅱ装置上获得的内爆靶丸掺Ar发射光谱实验数据,推断出靶丸芯区电子温度随时间的演化过程.  相似文献   

13.
Energy-loss moments of the electronic energy loss are calculated as functions of impact parameter for protons of 1 to 7 MeV incident upon Be, Al, Cu, Ag, and Ta targets. The Lindhard dielectric-function formalism is used, in the local-density approximation. The target-atom electron densities are Lenz-Jensen, and the projectile is a point charge. The moments are fitted by a simple algebraic function, and the energy and Z2 dependence of the parameters of this function are given.  相似文献   

14.
15.
The spectra of Ti Kα X-rays induced by He, C, N and O ions were measured with the use of a Bragg crystal spectrometer. The ratios of the integrated hypersatellite to diagram-plus-satellite X-ray yields were obtained. The previously obtained data on Cr, Fe and Ni Kα X rays induced by N ions were also analysed. It is found that the double K-shell vacancy production cross section is proportional to Z41.  相似文献   

16.
17.
发展了针对非局域热动平衡等离子体的K壳层电离平衡模型。模型中详细计算了各原子过程参数,并通过求解速率方程的稳态解得到各电离态的布居分布。在此基础之上,研究了谱线强度比值对等离子体温度、密度的依赖关系。最后,我们根据此模型的计算结果,分析了在神光II装置上获得的内爆靶丸掺Ar发射光谱实验数据,推断出靶丸芯区电子温度随时间的演化过程。  相似文献   

18.
19.
By varying the energy of fast protons incident on gold, europium, silver, ribidium and copper targets, it has been possible to produce several self consistent sets of relative K-shell ionization cross sections covering the region from below to above the velocity matching peak.  相似文献   

20.
Near the threshold energy, electron induced Mn and Cu K-shell ionization cross sections have been measured. Except for energies very close to threshold, the results are in good agreement with the semi-empirical formula of Green and Cosslett.  相似文献   

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