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物理学   27篇
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1.
The classical method within the independent electron model is employed to investigate (i) charge dependences of single and double ionization for helium by various charged ions A^q+ (q = 1 - 8) at impact energies of 0.64 and 1.44 MeV/u, respectively, (ii) energy dependences of transfer ionization for helium by 0.5-3 MeV/u A^8.9+ ions impact. The Lenz-Jensen model of the atom is applied instead of the Bohr model of the atom, and the impact-parameter dependences are also introduced into the calculations. Satisfactory agreement is found between theoretical and experimental data.  相似文献   
2.
The transmissions of oxygen ions through Al2O3 nanocapillaries each 50 nm in diameter and 10 μm in length at a series of different tilt angles are measured,where the ions with energies ranging from 10 to 60 keV and charge states from 1 up to 6 are involved.The angular distribution and the transmission yields of transported ions are investigated.Our results indicate both the existence of a guiding effect when ions pass through the capillary and a significant dependence of the ion transmission on the energy and the charge state of the ions.The guiding effects are observed to be enhanced at lower projectile energies and higher charge states.Meanwhile,the results also exhibit that the transmission yields increase as the tilt angle decreases at a given energy and charge state.  相似文献   
3.
We study the L x-ray emission from Zr, Mo and In targets and M x-ray emission from Pb target under bombardment of low energy Ar^q (q = 13, 14, 15, 16) ions. The relative x-ray yields were measured in the projectile kinetic energy range 210-360 keV. It is found that the relative x-ray yields from Zr, Mo and Pb targets increase with the increasing projectile kinetic energy for Ar^14 and Ar^16 projectiles and depend on the potential energy of the projectile remarkably.  相似文献   
4.
介绍了使用位置灵敏技术和飞行时间方法研究中低能低电荷态离子-原子碰撞过程中转移电离与单电子俘获过程.对于确定的入射离子电荷态,通过理论分析及与实验数据对比给出了转移电离与单电子俘获截面比RTS随着入射离子速度VP的变化规律和转移电离过程中电离的电子主要来自靶原子的最外亚壳层. 关键词: 转移电离 逃离半径 电离半径 俘获半径  相似文献   
5.
In this paper a projectile ions recoil ions coincidence technique is employed to investigate the target ionization and projectile charge state changing processes in the collision of 0.22-6.35 MeV Cq^+ (q = 1 - 4) ions with argon atoms. The partial cross section ratios of the double, triple, quadruplicate ionization to the single ionization (or the single capture) of argon associated with single electron loss (or single electron capture) by the projectile are measured and compared with the previous experimental results. In the present experiment, it is observed that the ratios of ionization cross sections R associated with single loss and single capture depend strongly on the projectile charge state and vary significantly with different reaction channels as impact energy increases. In addition, this paper gets empirical scaling laws for the ionization cross section ratios R corresponding to the projectile single loss and finds that the ratios of the double ionization to the single ionization associated with single electron capture remain constant in the present energy range.  相似文献   
6.
Jianjin Zhou 《中国物理 B》2022,31(5):50702-050702
In recent years, gas electron multiplier (GEM) neutron detectors have been developing towards high spatial resolution and high dynamic counting range. We propose a novel concept of an Al stopping layer to enable the detector to achieve sub-millimeter (sub-mm) spatial resolution. The neutron conversion layer is coated with the Al stopping layer to limit the emission angle of ions into the drift region. The short track projection of ions is obtained on the signal readout board, and the detector would get good spatial resolution. The spatial resolutions of the GEM neutron detector with the Al stopping layer are simulated and optimized based on Geant4GarfieldInterface. The spatial resolution of the detector is 0.76 mm and the thermal neutron detection efficiency is about 0.01% when the Al stopping layer is 3.0 μ m thick, the drift region is 2 mm thick, the strip pitch is 600 μ m, and the digital readout is employed. Thus, the GEM neutron detector with a simple detector structure and a fast readout mode is developed to obtain a high spatial resolution and high dynamic counting range. It could be used for the direct measurement of a high-flux neutron beam, such as Bragg transmission imaging, very small-angle scattering neutron detection and neutron beam diagnostic.  相似文献   
7.
Cross sections for charge transfer and ionization of atomic hydrogen by highly charged ions A^q+ (q =6 9) are evaluated using a simple and classical method based on the previous works by Bohr and Lindhard [K. Dan. Vidensk. Selsk. Mat. Fys. Medd 28 (1954) No 7], Brandt [Nucl. Instrum. Methods Phys. Res. 214 (1983) 93] and Ben-Itzhak et al. [J. Phys. B: At. Mol. Opt. Phys. 26 (1993) 1711]. It is proved that the present calculations are feasible to some extent in comparison with available experimental data and quantum calculations.  相似文献   
8.
A simple model for the direct ionization and transfer ionization probabilities in A^2++He collisions in a wide projectile energy range is proposed based on the Bohr-Lindhard model and the classical statistical model. The calculated cross sections are in satisfactory agreement with the experimental data available.  相似文献   
9.
The relative partial cross sections for ^13C^6+ -Ar collisions at 4.15-11.08 ke V/u incident energy are measured. The cross-section ratios σ^2E/σ^SC, σ^3E/σ^SC, σ^4E/σ^SC and σ^SE/σ^SC are approximately the constants of 0.514-0.05, 0.204-0.03, 0.064-0.03 and 0.024-0.01 in this region. The significance of the multi-electron process in highly charged ions (HCIs) with argon collisions is demonstrated (σ^ME/σ^SC as high as 0.794-0.06). In multi-electron processes, it is shown that transfer ionization is dominant while pure electron capture is weak and negligible. For all reaction channels, the cross-sections are independent of the incident energy in the present energy region, which is in agreement with the static characteristic of classic models, i.e. the molecular Coulomb over-the-barrier model (MCBM), the extended classical over-the-barrier model (ECBM) and the semiempirical scaling laws (SL). The result is compared with these classical models and with our previous work of ^13C^6+ -Ne collisions [Chin. Phys. Lett. 23 (2006) 95].  相似文献   
10.
极紫外(extreme ultraviolet, XUV)光与物质相互作用是探索微观粒子内部结构的重要方式.本文利用反应显微成像谱仪测量了Ne, Xe原子在XUV光作用下单电离与双电离的电子角分布,提取了Ne原子2p电子和Xe原子5p, 5s电子电离的β不对称参数,并结合前人已发表的实验数据与不同的理论模型进行对比.结果表明Ne原子2p壳层电子电离受电子关联效应影响较弱; Xe原子5p电子电离受电子关联效应影响强,且不受相对论效应的影响,但这两种效应在Xe原子5s电子电离过程中都发挥了重要作用.此外,研究还发现Xe原子双电离存在直接双电离和间接双电离两种机制,并给出了间接双电离第一步与第二步光电子角分布与β不对称参数信息.  相似文献   
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