K-shell ionization by protons for Cr, Cu, In and by alpha-particles for Cr, Cu

K-shell ionization cross sections have been determined for Cr, Cu and In at proton bombardment in the energy region from 0.9 to 2.5 MeV. The same cross sections were determined for Cr and Cu at alpha bombardment in the 0.9–4.0 MeV region. The experimental results are compared with five different theoretical calculations.     

Atomic K-shell ionization induced by 20–50 MeV protons

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.     

Mn and Cu K-shell ionization cross sections by slow electron impact

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.     

Measurement of Cu K-shell and Ag L-shell ionization cross sections by low-energy positron impact

Inner shell ionization cross sections by low-energy positron impact have been measured. Development of an x-ray detector with thin Si(Li) crystals has enabled the first measurements of the absolute cross sections for the positron impacts in the energy range below 30 keV. Threshold behavior of the measured cross sections for the Cu K shell and Ag L shell are compared with the theoretical results of Gryzinski and Kowalski [Phys. Lett. A 183, 196 (1993)]] and Khare and Wadehra [Can. J. Phys. 74, 376 (1996)]]. Good agreement has been found for the Cu K shell, while the experimental values for the Ag L shell were found to be smaller than the corresponding theoretical results.     

K-shell ionisation cross-sections of Cu,Ge, Mo,Ag and Sn by protons of energy 0.3 to 1.8 MeV

K-shell ionisation cross secions of Cu, Ge, Mo, Ag and Sn in proton impact have been measured systematically in the energy range 0.3 to 1.8 MeV. Thin targets have been used in transmission geometry. Data are compared with the predictions of the PWBA and the PWBA modified to include corrections due to Coulomb retardation of the projectile, increased binding of the target electron during collision and the relativistic nature of theK-shell electrons. The intensity ratiosK _α /K _β have also been obtained as a function of proton energy for all the five elements.     

K-shell ionization by high energy electrons

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.     

A scaling law for K-shell ionization by relativistic electrons

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.     

Measurements of K-shell ionization cross sections of35Br,37Rb,39Y using low energy protons

K-shell ionization cross section measurements are reported for₃₅Br,₃₇Rb and₃₉Y targets caused by protons over 300–400 keV energy range in 20 keV increment. The K-shell ionization cross sections (σ _k ^l ) at different energies were deduced from the K_α and K_β X-ray production cross sections which were obtained from X-ray yields of the K_α and K_β transitions. The experimental values are compared with the calculated values of ECPSSR theory and empirical reference cross sections. The resultant K-shell ionization cross sections are found to be in reasonable agreement with the ECPSSR theory. The K_α/K_β intensity ratios are also presented and compared with other experimental values and also with the theoretical one-hole values given by Scofield.     

Al,Ti,Cu,Mo原子的K壳层电离截面的理论计算

 电子离子碰撞过程是模拟激光等离子体的超热电子的能谱和产额的主要过程之一。基于相对论性的电子离子碰撞的K壳层的电离截面理论,计算了Al,Ti,Cu,Mo原子的K壳层的电子离子碰撞截面,结果和最近的文献实验数值和其它理论数值进行了比较,计算结果可用来模拟激光等离子体的超热电子能谱和产额。     

Al,Ti,Cu,Mo原子的K壳层电离截面的理论计算

电子离子碰撞过程是模拟激光等离子体的超热电子的能谱和产额的主要过程之一。基于相对论性的电子离子碰撞的K壳层的电离截面理论,计算了Al,Ti,Cu,Mo原子的K壳层的电子离子碰撞截面,结果和最近的文献实验数值和其它理论数值进行了比较,计算结果可用来模拟激光等离子体的超热电子能谱和产额。     

K-shell ionization of atoms and ions by relativistic projectiles

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.     

Impact parameter dependence of the probability for K-shell ionization by nuclei

The probability W for the atomic ionization by nuclei as a function of the impact parameter x is expressed through the ionization matrix element M_if. Values of W(x) for K-shell ionization calculated with the first Born M_if are compared with the experimental data and other calculations.     

非局域热动平衡等离子体K壳层电离平衡模型

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.     

第十五届全国原子与分子物理学术会议:非局域热动平衡等离子体K壳层电离平衡模型

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。     

Inelastic scattering and radiative capture of protons by Cr50 and Cr54

Total yields and angular distributions of gamma rays following the inelastic scattering of protons from Cr⁵⁰ and Cr⁵⁴ have been measured at proton energies below 2.5 MeV. Gamma ray spectra resulting from the proton radiative capture by Cr⁵⁰ and Cr⁵⁴ were obtained. Transitions from most of the Mn⁵¹ and Mn⁵⁵ low-lying levels have been observed. The experimental results are in good agreement with predictions of the statistical compound nucleus theory.     

Projectile charge-state dependence in K-shell ionization of neon,silicon, and argon gases by lithium projectiles

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.     

K-shell ionization cross sections in nearly symmetric collisions by S and Cl impact

K-shell ionization cross sections in collisions of S and Cl ions with target atoms with atomic numberZ ₂=11–22 have been measured in the energy range from 3.9 to 48 MeV. The data are interpreted in terms of the statistical model of electron diffusion to the continuum. The distribution ofK-vacancies between the projectile and the target atoms are discussed in the framework of the vacancy sharing process.     

Total, partial, and electron-capture cross sections for ionization of water vapor by 20-150 keV protons

We present experimental results for proton ionization of water molecules based on a novel event by event analysis of the different ions produced (and lost). We are able to obtain mass analyzed product ion signals (e.g., H2O+, OH+, O+, O++, H+) in coincidence with the projectile analyzed after the collision, i.e., either being H+, neutral H after single electron capture during the ionization event, or H- after double electron capture. After proper calibration we are thus able to determine a complete set of cross sections for the ionization of a molecular target by protons including the total and the partial cross sections and in addition also the direct ionization and the electron capture cross sections.