The European Physical Journal D最新文献

We describe the implementation of the current Flexible Atomic Code (FAC) unique electron central potential within the autostructure code. We show that the two codes then give the same atomic data for all practical application purposes. However, autostructure has more flexible potential options which can lead to a more accurate description of atomic processes, especially in low-charged ions.

Energy levels, transition rates, and electron-impact ionization and excitation cross sections for W I are calculated by multi-configuration Dirac–Fock (MCDF) method using the MDFGME code which aims at improving the accuracies of the atomic data which has been crucial for spectroscopic diagnostics of erosion rate of W in plasma surface interaction. Particular attention has been paid to the core–core (CC) and core–valence (CV) electron correlation effects on the level energies and radiative transition rates. The inclusion of the CC and CV electron correlations significantly improves an agreement with the atomic structure data based on experiments. The electron-impact ionization and excitation cross sections are obtained employing binary-encounter Bethe model and scaled plane wave Born approximation, respectively, from the wave functions by the MCDF calculation The obtained collision cross sections and rate coefficients are compared with other available data, which has been used to determine the erosion rate of W with spectral lines in the range of 400–525 nm.

The He({^+})–He collisions are treated with a three-electron atomic-orbital close-coupling method at intermediate energies. The cross sections are shown for single-electron capture, target excitation, projectile excitation, and target ionization. The results are overall in good agreement with experimental data and previous theoretical results. The minima in the cross sections for target excitation to (2{^1}S) and (2{^1}P) around 20 keV/u are also discussed.

Metastable levels of highly charged ions that can only decay via highly forbidden transitions can have a significant effect on the properties of high temperature plasmas. For example, the highly forbidden 3d(^{10}) (_{J=0}) - 3d(^9)4 s ((frac{5}{2},frac{1}{2})_{J=3}) magnetic octupole (M3) transition in nickel-like ions can result in a large metastable population of its upper level which can then be ionized by electrons of energies below the ground state ionization potential. We present a method to study metastable electronic states in highly charged ions that decay by x-ray emission in electron beam ion traps (EBIT). The time evolution of the emission intensity can be used to study the parameters of ionization balance dynamics and the lifetime of metastable states. The temporal and energy resolution of a new transition-edge sensor microcalorimeter array enables these studies at the National Institute of Standards and Technology EBIT.

NOMAD calculated time evolution of the ratio of the Ni-like and Co-like lines in Nd at varying electron densities compared with measured ratios

In this study, we conduct atomistic-level molecular dynamics simulations on fixed-sized silicon-germanium (Si(_{1-x})Ge(_{x})) crystals to elucidate the effects of dopant concentration on the crystalline inter-planar distances. Our calculations consider a range of Ge dopant concentrations between pure Si (0%) and 15%, and for both the optimised system state and a temperature of 300K. We observe a linear relationship between Ge concentration and inter-planar distance and lattice constant, in line with the approximation of Vegard’s Law, and other experimental and computational results. These findings will be employed in conjunction with future studies to establish precise tolerances for use in crystal growth, crucial for the manufacture of crystals intended for emerging gamma-ray crystal-based light source technologies.

Atomic cascades refer—first and foremost—to the stepwise de-excitation of excited atoms owing to the emission of electrons or photons. Apart from dedicated experiments at storage rings and synchrotrons, such cascades frequently occur in astro and plasma physics, material research, surface science and at various places elsewhere. In addition, moreover, “atomic cascades” have been found a useful concept for modeling atomic behavior under different conditions, for instance, when dealing with the photoabsorption of matter, the generation of synthesized spectra, or for determining a rather wide class of (plasma) rate coefficients. We here compile and discuss several atomic cascades (schemes) that help predict cross sections, rate coefficients, electron and photon spectra, or ion distributions. We also demonstrate how readily these schemes have been implemented within JAC, the Jena Atomic Calculator. Emphasis is placed on the classification of atomic cascades and their (quite) natural breakdown into cascade computations, to deal with the electronic structure and transition amplitudes of atoms and ions, as well as the cascade simulation of those properties and spectra, that are experimentally accessible. As an example, we show and discuss the computation of dielectronic recombination plasma rate coefficients for beryllium-like gold ions. The concept of atomic cascades and its implementation into JAC can be applied for most ions across the periodic table and will facilitate the modeling and interpretation of many forthcoming observations.

This work describes the tests performed with a newly built hollow-cathode lamp to ensure its capability to measure atomic parameters such as transition probabilities accurately. We discuss the design of the lamp and the experimental setup that will be used to measure transition probabilities. We show the discharge characteristics of the lamp and also the stability of spectral emission of the lamp over a period of two hours. Finally, it is concluded that the experimental setup, the lamp, and a camera with high resolving power are well suited for the measurement of the transition probabilities of doubly ionised rare-earths like Nd III.

Graphical abstract illustrating the use of a hollow-cathode lamp setup for accurately measuring branching fractions of rare-earth elements. The setup includes a diffraction grating spectrometer and a CMOS camera to detect radiation across a spectral range of 200 nm to 800 nm with a resolving power of 150,000 at 450 nm

In this paper, we present a detailed analytical computation of the triple differential cross section, in the first Born approximation, for the relativistic electron-impact ionization of the metastable atomic hydrogen H(2S) in the symmetric coplanar geometry and in the presence of a circularly polarized laser field. We introduce as a first step the Dirac–Volkov plane wave Born approximation 1 where we take into account only the relativistic dressing of the incident and scattered electrons. Then, we introduce the Dirac–Volkov plane wave Born approximation 2 where we take totally into account the relativistic dressing of the incident, scattered and ejected electrons. This paper is an extension of the previous one (Jakha et al. in Chin J Phys 77:1048, 2022), where we studied the same process in the absence of any external field. The combination of these two complementary works can provide a thorough and comprehensive study that can pave the way for any future experimental investigation.

It is shown that the masking process will be implemented successfully if the targeted masked qubit evolves by Hermitian or non-Hermitian energy operators. For a two-qubit system, we showed that a single ancillary (blank). A single qubit is sufficient to mask the encoded information in this two-qubit system. Similarly, the process can be performed if the initial qubits system evolves by Hermitian or non-Hermitian energy operator.