Determining the potential based on Rutherford backscattering data and electron screening in nuclear fusion reactions

A technique for determining the interaction potentials of He⁺–W, Ta systems on the basis of experimental data on the Rutherford backscattering of accelerated particles at an angle of 165° is proposed. This method provides an opportunity to extend the range of short distances within which the experimentally determined potential is known to 0.005 au and calculate corrections for electron screening relevant to the measurement of cross sections of the d + d nuclear fusion reaction. These corrections agree closely with the experimental data.     

The He(1s, 2s) + Ne interaction potential

A well depth D = 0.79 meV at R = 11.56 au is calculated for the excited He(1s, 2s) atom interacting with Ne by using a non-local pseudopotential method in good agreement with the experimental values. The pseudopotential I use also contains polarization effects in an adiabatic form. The contribution of the polarization to the well depth is calculated to be 0.42 meV.     

On the sputtering mechanism in the energy range of Rutherford backscattering

Sputtering rates for 100 keV protons incident normally on Cu and Pt films deposited on various base materials were determined from the energy spectrum of the backscattered protons. Sputtering is partly caused by ions backscattered from the base material.     

The potential energies of the Na** + He quasi-molecule

The special features of the behavior of the potential energy surfaces of the system comprising a highly excited A** atom and a neutral B atom with a filled electronic shell were thoroughly analyzed. This was done using the integral variant of theory combined with the generalized finite radius potential method correctly describing the scattering of a weakly bound electron by the B atom. The method allows P scattering to be taken into account. This scattering causes the additional splitting of potential energy surfaces into separate groups of interacting terms classified according to the projection m of the electron angular momentum l onto the quasimolecular axis. Calculations of the nl(^{2s + 1}Λ) state potential curves of the Na** + He quasi-molecule (n, l, and Λ are the principal quantum number, angular momentum, and its projection onto the molecular axis, and s is the spin of the system) were performed. The calculation results were compared to those obtained by other authors.     

The determination of the integrated condensation coefficient of gold on NaCl cleavage faces by Rutherford ion backscattering

The Rutherford backscattering technique has been applied for the absolute determination of the integrated condensation coefficient of gold on rocksalt cleavage faces. By this method the number of deposited atoms down to an average thickness of $\text{1}\text{100}$ monolayer can be measured. The experimental results at different substrate temperatures and times have been compared with sticking coefficients which are calculated from the nucleation and growth theory of thin films. The contact angle of the microscopic clusters of the deposit on the substrate has been determined from the number of deposited atoms, measured by ion backscattering, and the cluster distribution, measured by electronmicroscopy.     

He4-He4 interaction potential from low energy total cross section measurements

Total relative and absolute cross sections for He⁴-He⁴ have been measured between 110 and 1100 m/s velocity of the primary beam at scattering chamber temperatures of 5.0 and 77 K. Our measurements are sensitive to the low energy repulsive and the attractive part of the potential. The resulting potential is able to describe scattering measurements of other authors; it is also in very good agreement with ab initio calculations of Bertoncini and Wahl.     

The study of zirconium alloy coatings produced by microarc oxidation using Rutherford and nuclear backscattering spectrometry

The effect of the electrolyte composition during microarc oxidation of the E110 zirconium alloy on the corrosion resistance of coatings is investigated using proton Rutherford backscattering spectrometry, nuclear backscattering spectrometry, and other methods.     

低速多电荷态离子He2+、O2+和Ne2+与W靶表面相互作用的动能电子发射研究

本文报道了He2 ,O2 和Ne2 与W靶表面相互作用中的动能电子产额随离子入射速度变化的实验测量结果.结果表明:在本实验的入射速度范围内,对同一入射离子,动能电子产额随入射离子的速度增大而线性增加.基于动能电子发射的机理,我们分析了影响动能电子产额的因素,理论上得出动能电子产额与入射速度增长呈线性增加的关系,取得了实验上和理论上一致的结果.     

Altitude distribution of the auroral acceleration potential determined from cluster satellite data at different heights

Aurora, commonly seen in the polar sky, is a ubiquitous phenomenon occurring on Earth and other solar system planets. The colorful emissions are caused by electron beams hitting the upper atmosphere, after being accelerated by quasistatic electric fields at 1-2 R(E) altitudes, or by wave electric fields. Although aurora was studied by many past satellite missions, Cluster is the first to explore the auroral acceleration region with multiprobes. Here, Cluster data are used to determine the acceleration potential above the aurora and to address its stability in space and time. The derived potential comprises two upper, broad U-shaped potentials and a narrower S-shaped potential below, and is stable on a 5 min time scale. The scale size of the electric field relative to that of the current is shown to depend strongly on altitude within the acceleration region. To reveal these features was possible only by combining data from the two satellites.     

Oxidation of indium implanted aluminium studied by the Rutherford backscattering and perturbed angular correlation methods

Aluminium foils oversaturated with 5.10¹⁵/cm² implanted¹¹⁵In⁺ ions were oxidized in 200 mbar oxygen or vacuum annealed at 370–870 K. The samples were analyzed by the Rutherford backscattering (RBS) and perturbed angular correlation (PAC) techniques, using some 10¹¹/cm² implanted radioactive¹¹¹In tracers. Furthermore, the oxygen surface profiles were also scanned with high resolution by using the nuclear resonance technique (NRA). The formation of passivating Al₂O₃ surface layers, preventing deeper oxygen diffusion and the indium diffusion into these oxidized surface layers and into the bulk, were studied. Several quadrupole interaction frequencies previously attributed to strained cubic indium precipitates and indium (-vacancy) clusters were observed. When the samples were oxidized above 750 K, the formation of In-O complexes and of substitutional¹¹¹In in Al₂O₃ was observed.     

Determination of the element distribution in films deposited using the plasma focus facility by Rutherford backscattering

The C, Cu and W element profiles in films deposited using a plasma focus facility are studied by the Rutherford backscattering of 2-MeV He⁺ ions. The films are deposited onto glass substrates in Ar plasmaforming gas. The element profiles are found to depend significantly on the kinetic energy of particles. The penetration depth of particles with the velocity ~10⁵ m/s is about 1.5 μm. The corresponding element profiles showing the distribution of elements over the thickness of the glass are non-linear. For each element, the maximum layer depth is observed under the glass surface. The formation of Cu, W and C layers under the glass surface and their overlapping is a feature of films deposited using the plasma focus facility. Such an arrangement of layers evidences the significant difference between this method of film deposition and conventional techniques at low rates of atom deposition, as well as diffusion-based methods. The obtained films are found to have dielectric properties.     

Fusion cross section from statistical analysis of4He+197Au reaction data

An approach for an estimation of the fusion cross section by combining the available experimental data with the statistical simulations is proposed. An important step is the correction of the experimental excitation functions for the noncompound contributions. The ratio of the corrected total evaporation excitation functions to the calculated ones allows to estimate the fusion cross section. The proposed scheme has been applied to the⁴He+¹⁹⁷Au reaction data. The approach provides a basis for a consistent comparison between a particular complete-fusion model and experiment.     

The neutralisation of low energy He+ scattered from Ni

The neutralisation of low energy He⁺ scattered off polycrystalline Ni is investigated using three-dimensional angular resolving ion scattering spectroscopy. It is found that upto 98% of the neutralisation occurs during the collision event.     

Generator-coordinate study of 3He+3He elastic scattering with a semirealistic nucleon-nucleon potential

The elastic scattering of ³He by ³He is studied in the framework of the generator coordinate method, using a new semirealistic nucleon-nucleon potential. All components of this potential have a soft core in the sense that they can be used in calculations where short-range correlations between nucleons are not taken into account. With this potential, a good agreement between calculated and measured cross sections and polarizations is obtained. The tensor component of the potential is found to be essential to explain the J-dependence of the empirical phase shifts, although the calculated polarizations are insensitive to the strength of the tensor potential.     

Investigation of the long-range effect of light irradiation by means of Rutherford backscattering/ion channeling spectroscopy

This paper presents the results of the first experiments on the observation of the long-range effect by means of Rutherford backscattering/ion channeling spectroscopy under irradiation of a silicon crystal by visible light.     

Determination of the interaction potential of the Li+-He system relative to the experimental differential cross sections

Reassessment of the interaction potential relative to the experimental differential scattering cross sections of Li⁺ ions by He at energies from 3.64 to 218 eV is carried out in this present report by the method published in 1970 by L. G. Yakovlev and É. M. Bashirov. The numerical values obtained for the potential are approximated by the formula (in eV)V(r)=398·exp(-4.90r) ?8.47 exp(?3.31r) eV. This formula gives values of the potential over the range of spacing from 0.5 to 1.5 Å. Comparison with other well-known data shows the excellent agreement of the results, but the use of the proposed method permits the potential to be determined over a wider range of spacings.