Quasimolecular KX-ray excitation by bombarding As,Zr, Nb,Mo and Rh target with Nb ions

By bombarding various targets with 65 MeV and 40 MeV Nb ions continuous X-ray distributions have been obtained, which range up to the KX-ray energies of quasiatoms woth Z=Z₁+Z₂. The hogh-energy parts of these continua are interpreted as KX-radiation of quasimolecules transiently formed during the adiabatic heavy-ion atomic collisions.     

Quasimolecular K X-ray excitation by bombardment of Ge atoms with Ge ions

By bombardment of Ge targets with ⁷⁴₃₂Ge⁵⁺ of 81 MeV, a continuous X-ray intensity distribution has been obtained, which ranges up to the K X-ray energies of ₆₄Gd. The shape of the spectra, corrected for the detector efficiency, confirms the assumption that this continuum is caused by K X-rays of Z = 64 quasimolecules, which are transiently formed during the adiabatic heavy-ion collision. The yield of quasimolecular radiation was determined to be about 4 x 10⁻⁵ X-rays per beam K-vacancy.     

Sputtering and backscattering of keV light ions bombarding random targets

The fission fragment fluence required to render CaUO₄, Na₂U₂O₄, MgUO₄, Sr₂U₃O₁₁ and u₃O₈ x-ray amorphous was deduced as ～5 × 10¹⁵ events cm³. Significant annealing of the structural damage occurred in the 300–-500°C range.     

Excitation of K X-Rays by bombardment of thick solid targets with 150 MeV Xe ions

The yield of K X-radiation arising from the interaction of ¹³⁶₅₄Xe ions with ₄₁Nb, ₄₂Mo, ₄₅Rh, ₄₆Pd, ₄₇Ag, ₄₈Cd, ₄₉In, ₅₀Sn, ₅₇La, ₆₄Gd, ₆₅Tb, ₇₀Yb, ₇₁Lu, ₇₃Ta, ₇₇Ir, ₇₈Pt, ₇₉Au and ₈₃Bi targets was measured using Si(Li) and Ge(Li) detectors. The dependence of the yield on the atomic number of the target material is discussed on the basis of the molecular orbital model.     

7.0MeV的Xe30+入射Au靶引起Xe L、M壳层电子的多重激发简

探测了7.0MeV动能的129 Xe30+离子入射Au靶激发的Xe L-X射线谱.研究了Xe L、M壳层空穴的形成机制及Xe的M、N、O壳层伴存空穴对L-X射线能量与半高宽的影响.结果表明,由于大量伴线的产生,Xe的Lα、Lβ、Lβ2,15、Lγ1-X射线峰中心能量与无伴线的文献数据相比变大,峰的半高宽相对探测器的分辨率出现不同程度的增宽.     

几类源打“新靶”和“旧靶”的对比实验

 根据氢气放电源、X光机X射线源和TiT源打“新靶”和“旧靶”的对比实验结果，证明了在氢气放电过程中产生了一种未知粒子，新谱线正是射线源轰击这种储存在“旧靶”中的未知粒子产生的。以此为依据得到如下推论：探测到的新谱线反映了未知粒子的能级特性，是未知粒子的能级谱线，所以这些新谱线是未知粒子存在的标志。     

Multiple electromagnetic excitation with relativistic heavy ions

The multiple electromagnetic excitation with fast projectiles (heavy ions) is studied theoretically in the sudden approximation. Of special interest is the excitation of rotational states coupled to giant (dipole) vibrations. Closed form expressions are obtained for the excitation of a rigid rotor. The strong pulse of high energy equivalent photons in relativistic heavy ion collisions opens up new possibilities for nuclear structure studies, not possible e.g. with electron scattering or nuclear Raman scattering. It is also pointed out that the “Brink-hypothesis” can be investigated in a new way by means of multiple electromagnetic excitation with relativistic heavy ions of low lying states coupled to the giant dipole mode.     

Two-electron excitation in helium-like ions by electron impact

Calculation of cross-sections for the two-electron excitation in helium-like ions by electron impact employing Coulomb-Born-Oppenheimer (CBO) approximation is presented. Analytical expressions for the differential and total scattering cross-sections without using partial wave expansion of the wavefunction reported earlier have been used. The total and differential scattering cross-sections for each of the excitations 1s ^{2 1} S* → 2s ^{2 1} S ^e , 2s2p ^1.3 P ⁰, 2p ^{2 1} S ^e ,³ P ^e,¹ D ^e in Be²⁺ and B³⁺ are computed. Results for Li⁺ reported earlier are also included for comparison.     

Multielectron processes in collisions of Xe23+ ions with Ar atoms

We report the measurements of relative cross sections for multielectron processes in collisions of Xe²³⁺ ions with argon atoms in the velocity range of 0.65–1.32 a.u. By means of the coincidence time-of-flight (TOF) technique, the final charge states of both the projectile and target ions for each collision event are determined. The present experimental data are compared with the scaling law by Selberg et al. [Phys. Rev. A 54, 4127 (1996)] and the extended classical over-barrier (ECB) model.     

Ionization of helium-like ions with excitation of nl states by high-energy photon scattering

The kinetic and spectral characteristics of the complex dielectric constant of a Ce: YAG crystal under laser irradiation in 250–275 nm spectral range are investigated. The lifetimes of free charge carriers and charge carriers, localized at the lattice defects (color centers), are estimated. It was established that photoconductivity signal of the sample is essentially caused by one-photon ionization processes from the ² F _5/2 ground state of Ce³⁺ ions.     

On excitation and loss of an electron by incident ions in relativistic collisions with atoms

The excitation and loss of an electron by ions in relativistic collisions with atoms are studied in first-order perturbation theory. General expressions are obtained for the cross sections for the excitation and loss of an electron. In the limit of nonrelativistic collision velocities these expressions pass into the well-known nonrelativistic results. It is shown that, in contradistinction to the nonrelativistic collisions, in ultrarelativistic collisions the screening of the nucleus of the target atom by the atomic electrons is very important for excitation and loss of an electron by ions even for collisions of heavy ions with light atoms. Our computational results for the cross section for electron loss are in good agreement with existing experimental data.     

杂质元素特征X射线对氢气放电源打靶新谱线的影响

在氢气放电源打靶的实验中,测到了系列能量恒定不变的低能X射线新谱线,这些新谱线的能量分别为(1.70±0.10) keV, (2.25±0.07) keV,(2.56±0.08) keV,(3.25±0.10) keV和（3.62±0.11） keV,与Si,Ta,S,Cl,K和Ca等元素的特征X射线能量相近,但靶中所含的杂质或来自放电室的杂质元素可能会产生这些能量的X射线谱峰,证实新谱线是否由这些元素的特征X射线干扰所致显得尤为重要。分析了本实验系统中各种杂质的可能来源,论证了放电室端杂质对新谱线的影响,及靶材料中体杂质和面杂质对新谱线的影响;用X射线光电子能谱仪对靶做了表面分析。研究结果表明：杂质元素的特征X射线不会对氢气放电源打靶产生的新谱线有影响。这些新谱线的性质有待进一步的实验研究。     

Ionization and excitation of some atomic targets and metal oxides by electron impact

We have calculated total inelastic and total ionization cross-sections for collisions of electrons on atomic targets oxygen (O), aluminium (Al) and copper (Cu) and metal oxides AlO and Al₂O, at impact energies from near excitation threshold to 2000 eV. A complex (optical) energy-dependent interaction potential is used to derive total inelastic cross-sections resulting from ionization as well as excitation processes. The inelastic cross-sections are bifurcated into discrete and continuum contributions and total ionization cross-sections have been deduced therefrom. Our calculation also provides information, hitherto sparse, on the excitation processes in the atomic targets O, Al, Cu and metal oxides AlO, Al₂O. Adequate comparisons are made with other theoretical and experimental data.     

Vibrational excitation by positron collisions with molecular gases: a study of O and NO targets

The scattering of slow positrons from and NO molecules is treated using exact static interactions and a model potential for correlation-polarisation forces. The quantum coupled equations for the elastic scattering are extended to vibrationally inelastic processes and the different excitation probabilities are evaluated. Comparison with existing experiments for the NO target indicates that the present calculations provide a realistic treatment of positron scattering below Ps formation and give computational estimates on the efficiency of such projectiles in producing vibrationally excited molecules in the ambient gas. Received: 23 April 1999 / Received in final form: 3 June 1999     

杂质元素特征X射线对氢气放电源打靶新谱线的影响

 在氢气放电源打靶的实验中,测到了系列能量恒定不变的低能X射线新谱线,这些新谱线的能量分别为(1.70±0.10) keV, (2.25±0.07) keV,(2.56±0.08) keV,(3.25±0.10) keV和（3.62±0.11） keV,与Si,Ta,S,Cl,K和Ca等元素的特征X射线能量相近,但靶中所含的杂质或来自放电室的杂质元素可能会产生这些能量的X射线谱峰,证实新谱线是否由这些元素的特征X射线干扰所致显得尤为重要。分析了本实验系统中各种杂质的可能来源,论证了放电室端杂质对新谱线的影响,及靶材料中体杂质和面杂质对新谱线的影响;用X射线光电子能谱仪对靶做了表面分析。研究结果表明：杂质元素的特征X射线不会对氢气放电源打靶产生的新谱线有影响。这些新谱线的性质有待进一步的实验研究。     

129Xe20+入射Au表面X射线产额与离子动能的相关性

报道了在兰州重离子加速器国家实验室320kV高电荷态离子综合研究平台上,用2.4~6.0MeV动能的高电荷态离子129Xe20+轰击Au表面,探测X射线谱的实验结果。当离子动能较大时,相互作用不仅激发出了Au的M-X射线,还激发出了Xe的L-X射线,且X射线产额随入射离子动能的增加总体呈增加趋势。对碰撞导致X射线产生的微观机制进行了初步分析。