The European Physical Journal D最新文献

We investigate how the above-threshold ionization by an intense circularly polarized infrared laser pulse is modified in the presence of a strong circularly polarized terahertz pulse. It is shown that both the differential ionization probability and the maximum photoelectron kinetic energy can be increased or decreased by an order of magnitude by changing the time delay between the laser and terahertz pulses. The results obtained by numerical integration agree well with those obtained using the modified saddle-point method. The used laser and terahertz pulse parameters are readily available at the modern experimental facilities.

In this article, we propose an alternate approach to study confined two-electron systems using the modified form of the Le Sech wavefunction. In the present approach, rather than using the cut-off factor in the variational wavefunction, we determine it directly by solving Schrödinger like equation. The results for kinetic energies, electron-nucleus interaction, electron–electron interaction, total energies, densities, ionization energies, and moments of confined (hbox {H}^-) and He atom are compared with the most accurate values found in the literature to show the effectiveness of our method. The present approach applies to a wide range of confinement potentials. We demonstrate it by showing the results for Coulomb, harmonic oscillator, and soft-confinement potentials.

In the present work, we address the problem of single ionisation in ion molecule collisions by implementing the dynamic charge continuum distorted wave—eikonal initial state model. A dynamic charge that depends simultaneously on both the emission angle and the emission energy is used to approximate the non-Coulomb potential of the residual molecular target. The molecular ground state is described employing a complete neglected of differential overlap approximation. The results in terms of total, single, and doubly differential cross sections are calculated and compared with available experimental data. Also, the contribution of each molecular orbital to the total cross section has been considered.

The Wentzel–Kramers–Brillouin approximation is applied to study the light scattering properties of an arbitrarily oriented cubic particle. The form factor and extinction coefficient of this particle are expressed in simple analytical expressions. The effects of certain physical parameters, namely angles of incidence, scattering azimuthal and zenith angles, refractive index and size parameter, on the form factor and extinction coefficient are analyzed. Some numerical examples are also presented to illustrate the results.

Electron-ion collision spectroscopy of the KLL dielectronic recombination (DR) resonances of hydrogenlike xenon ions was performed at a heavy-ion storage ring with a resolving power that is competitive with x-ray spectroscopy of inner-shell transitions in highly charged ions. The (KL_{1/2}L_{1/2}), (KL_{1/2}L_{3/2}), and (KL_{3/2}L_{3/2}) resonance groups and even parts of their fine structure are individually resolved. The resonance strengths were measured on an absolute scale and compared with results from multi-configuration Dirac–Fock (MCDF) calculations. These are in excellent agreement with the experimental findings when QED effects on the resonance energies and the Breit interaction are considered. As already found for DR of hydrogenlike uranium (Bernhardt et al. in Phys Rev A 83:020701(R), 2011), this interaction is particularly strong for the (KL_{1/2}L_{1/2}) resonance group. For U(^{91+}), it increases the (KL_{1/2}L_{1/2}) DR resonance strength by 40%. For Xe(^{53+}), the increase is found to amount to 25%, confirming the prediction that the influence of the Breit interaction grows with increasing nuclear charge. A comprehensive appendix treats the derivation of experimental and theoretical merged-beams recombination rate coefficients for interacting beams of relativistic electrons and ions.

The effects of gravitational force on the behavior of collisionless shock waves in a nonthermal dusty plasma with fluctuating charge have been examined. The distribution function describing a cold beam of dust grains under the influence of gravitational effects has been reanalyzed, resulting in the derivation of a new density expression. Numerical integration of the Poisson equation, coupled with the dust grain charge equation, reveals that the electrostatic potential associated with DA shock waves forms an asymmetric, oscillatory structure when gravitational effects are considered. Specifically, we have found that due to gravitational effects, the electrostatic potential inherent to the DA shock waves undergoes a jump and increases linearly and the amplitude of each oscillation decreases as the nonthermality of the electrons becomes more important. Furthermore, for medium-sized grains, the interplay between electrostatic potential and gravitational forces results in a shift of the multilayer structure toward higher potential values, along with an increased number of oscillations. This effect becomes even more pronounced for larger grains. The results of our investigation may contribute to a deeper understanding of shock structures in inhomogeneous media obtained in a controlled laboratory environment and may also have practical applications in interpreting similar phenomena in astrophysical contexts.

Because the dust from beryllium (Be) is toxic to humans, ITER has recently decided to replace the first wall material of Be with tungsten boron (B). While there has been much discussion on the electron-impact ionization (EII) cross sections for Be-containing molecules, EII data is still limited for fusion-relevant molecules containing B. We report the EII cross section for the fusion-relevant diatomic molecules BH, BN, BO, BF₃ and WB using the Binary-Encounter-Bethe (BEB) and Deutsch-Märk (DM) methods and evaluate its accuracy based on the available experimental data. The errors between our BEB and DM cross sections for these molecules are within 23%.

The nonlinear dynamics of a quasi-1D BEC loaded in a double-well potential is studied. The beyond-mean-field corrections to the energy in the form of the Lee–Huang–Yang term are taken into account. One-dimensional geometry is considered. The problem is described in the scalar approximation by the extended Gross–Pitaevskii (EGP) equation with the attractive quadratic nonlinearity, due to the Lee–Huang–Yang correction, and the effective cubic mean-field nonlinearity describing the residual intra- and inter-species interactions. To describe tunneling and localization phenomena, a two-mode model was obtained. The frequencies of the Josephson oscillations are found and confirmed by the full numerical simulations of the EGP equation. The parametric resonance in the Josephson oscillations, when the height of the barrier is periodically modulated, is studied. The predictions of the dimer model, including the case of the one-dimensional Lee–Huang–Yang superfluid, have been proven.