Scattering of charged particles by atoms

A closed variant of the Born approximation for calculating differential scattering cross sections in ion-atom collisions is developed. An expression in terms of the matrix elements J _ij with respect to the single-electron states of the atom is found for the matrix element describing the target atom in the formula for the differential cross section. The matrix elements J _ij are averaged over the relative orientation of the momentum transferred in the collision and the symmetry axis of the electronic orbitals of the target atom, using the single-electron Rutaan-Hartree-Fock wave functions. The algebraic representation of the matrix elements J _ij makes it possible to perform calculations for atoms with any value of Z. The model developed is used to calculate the cross sections σ_Σ and characteristic scattering angles θ_c for the process of electron loss by H^? ions with energy E = 0.1–100 MeV in targets consisting of atoms with Z = 2–54. It is shown that σ_Σ ∝ E ^?1 and θ_c ∝ E ^?1/2 for all Z, and for fixed E the behavior of σ_Σ(Z) and θ_c(Z) is determined by the order of filling of the electronic shells of the target atoms (the ionization potential). The computational results are analyzed and compared with the experimental data and the results of other calculations.     

Ionization of atoms by charged particles

Ionization of hydrogen atom by charged particle impact are studied at different collisional energies and the total and differential cross sections are calculated. In case of light particle impact the final-state wave function here considers all three two-body interactions on an equal footing and satisfies the exact Coulomb boundary conditions. The spin asymmetries are also found and the values are compared with other existing results. For heavy particle impact a final continuum state wave function which incorporates distortion due to the Coulomb fields of both the projectile and the target nuclei is employed. In this case the target hydrogen atom is considered in its ground as well as metastable 2s state. The results thus obtained are compared with the existing experimental findings as well as other theoretical predictions.     

Trapping of charged particles by transverse electromagnetic waves

An estimate is made of the maximum number of resonant particles interacting with a transverse plane electromagnetic wave. This estimate is based on the distribution function, in terms of integrals characterizing the motion of particles in a wave. The values found here for proton fluxes accelerated by an amplitude-modulated wave in the solar corona agree with those measured during sporadic radioemission bursts.     

Generation of surface polarization fields by charged particles

The electromagnetic surface polarization fields induced on the surface of a solid by moving charged particles are calculated. The case when a particle moves parallel to the surface is analyzed in detail.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 94–99, January, 1995.     

Deceleration of charged particles by matter in a magnetic field. II

The Green's function of the charged-particle transport equation is found in the continuous-retardation approximation, on the basis of the leading-center model.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 30–34, November, 1993.     

Channeling problem for charged particles produced by confining environment

Channeling problem produced by confining environment that leads to resonance scattering of charged particles via quasistationary states imbedded in the continuum is examined. Nonmonotonic dependence of physical parameters on collision energy and/or confining environment due to resonance transmission and total reflection effects is confirmed that can increase the rate of recombination processes. The reduction of the model for two identical charged ions to a boundary problem is considered together with the asymptotic behavior of the solution in the vicinity of pair-collision point and the results of R-matrix calculations. Tentative estimations of the enhancement factor and the total reflection effect are discussed. The text was submitted by the authors in English.     

Inelastic scattering of charged particles by a statistical atom

The angular and energy distribution of secondary electrons ejected in collisions of heavy charged particles has been calculated in the binary encounter approximation using the statistical Thomas-Fermi method. Comparisons are made with reported experimental results.     

Diffraction scattering of charged particles

It is shown that, contrary to popular belief, diffraction scattering in nuclear and particle physics is not always of Fraunhofer type. By establishing a simple physical connection between scattering in a Coulomb field and Fresnel diffraction we show that diffractive collisions of heavy charged particles are predominantly of Fresnel type. We derive quantitative criteria for Fraunhofer and Fresnel scattering which lead to a classification of all scattering processes by means of a “diffraction diagram.” This enables us to make specific predictions about the gross structure of angular distributions for any experimental conditions.     

Dynamics of a beam of charged particles. II

A perturbational method for calculating the effect of the electromagnetic field generated by particles on their motion is proposed. The expansion of a uniformly dense cylindrical beam of relativistic charged particles due to their own field is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii. Fizika, No. 11, pp. 42–44, November, 1992.     

Transport of charged particles by adjusting rf voltage amplitudes

We propose a planar architecture for scalable quantum information processing (QIP) that includes X-junctions through which particles can move without micromotion. This is achieved by adjusting radio frequency (rf) amplitudes to move an rf null along the legs of the junction. We provide a proof-of-principle by transporting dust particles in three dimensions via adjustable rf potentials in a 3D trap. For the proposed planar architecture, we use regularization techniques to obtain amplitude settings that guarantee smooth transport through the X-junction.     

Electromagnetic fields and potentials generated by massless charged particles

We provide for the first time the exact solution of Maxwell’s equations for a massless charged particle moving on a generic trajectory at the speed of light. In particular we furnish explicit expressions for the vector potential and the electromagnetic field, which were both previously unknown, finding that they entail different physical features for bounded and unbounded trajectories. With respect to the standard Liénard–Wiechert field the electromagnetic field acquires singular δ$\delta$-like contributions whose support and dimensionality depend crucially on whether the motion is (a) linear, (b) accelerated unbounded, (c) accelerated bounded. In the first two cases the particle generates a planar shock-wave-like electromagnetic field traveling along a straight line. In the second and third cases the field acquires, in addition, a δ$\delta$-like contribution supported on a physical singularity-string attached to the particle. For generic accelerated motions a genuine radiation field is also present, represented by a regular principal-part type distribution diverging on the same singularity-string.     

Electron-positron pair production by collisions of non-relativistic charged particles

The cross-section for (e ⁺,e ^?)-pair production in collisions of non-relativistic charged particles has been calculated to lowest order in the fine structure constant and leading power of the relative velocity of the colliding particles. Thus the deflection of colliding particles is included in one-photon-exchange approximation, while the Coulomb distortion of the (e ⁺,e ^?)-pair is omitted. We have laid particular emphasis on current conservation. The previously neglected contribution of the spatial part of the current turns out to be dominant.     

Two-cluster scattering ofN charged particles

We define geometrically two-cluster scattering states by their asymptotic space-time behavior. We show that these subspaces coincide with the ranges of the two-cluster wave operators, or modified wave operators if both clusters are charged. In particular this proves asymptotic completeness and absence of a singular continuous spectrum of the Hamiltonian below the lowest three-body threshold.     

Angular scattering of spinor charged particles by a Kerr-Newman field

The effect of nondiagonality of the metric tensor on the differential scattering cross section of spinor charged particles by a charged gravitational Kerr-Newman field is considered in first Born approximation. In particular cases, when the momentum of the particle before scattering: a) lies in the equatorial plane and b) is oriented along (against) the axis of rotation of a hole, expressions are obtained for the square of the scattering matrix element and the term in the cross section due to the appearance of the metric nondiagonality. The nonrelativistic and ultra-relativistic limits of these expressions are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 52–57, August, 1979.In conclusion, I thank the Senior Scientific Official of the chair of quantum theory in the Physics Faculty of V. R. Khalilov State University, Moscow, for inestimable assistance in the project.     

Confinement of charged dust particles by a hybrid-type electric curtain

The hybrid-type electric curtain (HTEC) comprises a planar electric curtain and a perpendicular planar condenser. Serial cylindrical electrodes are supplied with AC voltage, whereas the condenser is fed with DC voltage. HTEC allows for better control of the particle position shift in space. The particle oscillation path within the hybrid curtain has been photographically analysed. The changing particle path was recorded according to a DC changing voltage value and a constant AC voltage value. The aim of the paper is to describe a successful method that enables one to experimentally determine the region where the particle can be stably oscillated.     

Charge to radius dependency for conductive particles charged by induction

Particle charge is a critical parameter that needs to be determined in order to accurately predict behavior of a charged particle exposed to electrical forces. The effectiveness of various electrostatic applications depends directly on this charge or, more specifically, the charge to mass ratio. Previous studies report conflicting data for the size dependency of charge. In this paper, the relation between the value of charge on a conductive particle and the particle radius in the process of induction charging is investigated. The results of numerical simulations of a liquid atomization process are presented and a novel approach to the analytical solution of the problem is introduced. It is found that the exponent in the particle charge to radius dependency is equal to two when the particle is in the direct contact with the bulk material. The radius exponent decreases rapidly as the atomizing ligament length is increased. For ligament lengths many times greater than the particle radius, the radius exponent approaches one. Agreement between numerical and analytical results is found to be very good. The results of this study clarify some of the conflicting data in the previously published literature and suggest that the particle charge is practically linearly dependent on radius for atomized liquid particles and proportional to particle surface area for solid particles. In addition it is shown that the charge to mass ratio for liquid particles can be maximized by ensuring the ligament length during atomization is maximum.     

Retardation of charged particles by matter in a magnetic field

The Green's function of the steady transfer equation of charged particles in matter in the presence of a constant homogeneous magnetic field is found by the fifth-parameter method in the continuous-retardation approximation. The influence of the field on the particle penetration depth in matter is investigated.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 13–15, July, 1991.     

Spectroscopy of charged particles elastically scattered by plane-parallel solid layers

The energy spectra of electrons elastically scattered by plane-parallel solid layers are presented. The solid surface is analyzed by a method based on the identification of similar spectra and is called electron Rutherford scattering in analogy with the well-known ion spectroscopy method. The effect of multiple scattering processes on peak intensities in the energy spectra of elastically scattered particles is analyzed. The applicability range of the strong single scattering approximation for the interpretation of the energy spectra of elastically scattered electrons is established.