The European Physical Journal D最新文献

We report new investigations for the five differential cross section (FDCS) of the double ionization of methane by fast electron impact. The present study is performed within the first and second Born approximation. The target initial state is described by a single-center wave function of Moccia, while we represent the final state by using the approximate 3C model with the usual Gamow factor then with the Ward and Macek factor as a corrected version. The different mechanisms have been identified for specific kinematic conditions.

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We report on the absolute excitation cross sections of the lowest-lying optically allowed transitions in difluoromethane (CH₂F₂) molecules at intermediate impact energies between 100 and 400 eV and for scattering angles of 1.5° to 15°. The energy loss ranges from 8.5 to 11 eV, which has been assigned as the optically allowed 3s ← 2b₂ and 3p ← 2b₂ overlapping with the dipole-forbidden 1¹A₂ ← X¹A₁ excitations. The absolute scale of the corresponding cross sections is obtained by normalizing the angular distributions of inelastically scattered electrons to the absolute excitation differential cross section (DCS) of He as the reference. The excitation integral cross sections (ICSs) for these excitations obtained by the generalized oscillator strength analysis are in reasonable agreement with the corresponding BE-scaled ICSs derived recently at an impact energy of 1500 eV within the experimental uncertainties. The absolute measurement suggested that the BE-scaling law is experimentally confirmed to be quite useful for CH₂F₂ molecules even at intermediate electron energies.

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In this study, we present experimentally determined transition probabilities of 86 singly ionized cerium emission lines. We used a widely employed spectroscopic technique, laser-induced breakdown spectroscopy (LIBS), to measure the transition probabilities considering the great demand for experimentally determined atomic data. In astrophysics, cerium is a significant element of interest, especially when examining kilonova emissions that are observed following the merging of two neutron stars. The experimental data are compared with previously reported data.

Traditional ghost image (GI) relies on the intensity fluctuation correlation between the reference beam and the object beam. In this paper, a novel analysis for characteristic recognition ghost imaging (CRGI) is proposed based on characteristic classification of the light field, which indicates that GI can be considered as the superposition of ghost images with different characteristic information. The analytical results show that the reconstructed images of GI by processing the reference light are identical to that by processing the object light, which make it possible to utilize the prefabricated reference light to recognize the target characteristic in the imaging process. Moreover, the distinction between targets can be clearly identified by CRGI when the difference of characteristic information is quite slight, while it is difficult to be distinguished in traditional GI. Our results not only provide a new method for real-time characteristic recognition, but also promote the development of GI technology in fields such as medical imaging and security systems.

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This diagram depicts the process of achieving target characteristic recognition by pre-processing the reference light

This study focuses on new identifications of discrete spectral lines of heavy ions with one or two outermost 4s/4p subshell electrons in soft X-ray and extreme ultraviolet regions. The study is basically based on the spectroscopic data systematically taken in the last decades in high-temperature plasmas produced in the Large Helical Device using multiple grazing incidence spectrometers. In addition, we have newly taken spectroscopic data using the Tokyo electron beam ion trap (EBIT) for some of the missing elements in the past EBIT experiments. Consequently, we could identify a number of discrete lines experimentally for the first time in this study based on the detailed atomic number (Z)-dependences of the wavelengths of major resonance lines. Some transitions of Ga- and Ge-like ions show irregular Z-dependences in which the transition wavelength suddenly shifts to another curve at around a specific Z due to the effect of strong configuration interaction.

We present a theoretical investigation to study the ionization reaction of the water molecule in its ground state by positron and electron impact, from low to intermediate impact energies. The triple differential cross section (TDCS) is calculated using the M3CWZ model, where each particle in the continuum is represented by a Coulomb wave with a variable charge Z(r), and the post collision interaction (PCI) is included and exactly treated. Numerical results are compared with available data and other theories in a wide range of kinematics. It is found that M3CWZ results reproduce quite well the data at intermediate and low impact energies for electron impact process. For positron impact, our results are in good agreement with theoretical predictions and show interesting trends that should be confirmed by future experiments.

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Soft confinement potential provides a more realistic model for physical systems, such as many-body interactions, atomic clusters, and ion trap, making it a hot topic of current research. In this study, the photodetachment dynamics of the H⁻ ion in a soft confinement potential ((z/d)^N) is investigated using closed orbit theory (COT). The photodetachment cross section (PCS) of this system is shown to be highly sensitive to the stiffness (N) and confinement width (d) of the potential. When N is odd, the photodetachment dynamics resembles that in a uniform electric field, resulting in a relatively simple oscillatory structure in the PCS. For even N, the force acting on the detached electron becomes a restoring force, leading to periodic oscillation of the detached electron. This makes the oscillatory structure in the PCS more complex. Additionally, the oscillating amplitude of the PCS decreases as N increases, and for very large N, the PCS approximates that of a system near a hard wall (for odd N) or in a quantum well with two hard walls (for even N). This study highlights that by varying the parameters of a soft confinement potential, researchers can precisely regulate the photodetachment of negative ions in various external field environment. These findings offer valuable insights into how soft confinement potentials affect negative ions, advancing both fundamental research and practical applications, such as photodetachment microscopy, ion manipulation, and ion trap.

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