The European Physical Journal D最新文献

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.

Graphical abstract

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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The proposed quantum Stirling machine is a groundbreaking advancement in the field of quantum machines. The machine is used as a highly efficient heat engine and an innovative refrigerator. In our analysis, we examine the property of the machine by treating its working substance as a two-qubit Heisenberg model operating under the influence of a magnetic field within the framework of Tsallis formalism. The novelty of this work is to use the non-extensive thermodynamics in studying the quantum Stirling machine. We investigate the influence of the non-extensive Tsallis parameter and magnetic field on various aspects of the Stirling heat engine and refrigerator, including absorbed heat, released heat, work done, efficiency, and performance coefficient (PC). The findings show that the non-extensive parameter has an important role in the efficiency and PC. The best value for the efficiency can be obtained when the non-extensive parameter approaches one, whereas it occurs for the PC when the parameter approaches 0.1. By carefully selecting the system parameters, it is possible to optimize the Stirling cycle's efficiency and PC, allowing it to function effectively as both a heat engine and a refrigerator.

Graphical Abstract

Absorbed and released heat and the work done

It is shown that the dipole photoabsorption cross section of almost all subshells of all atoms behaves as E^−7/2 in the high-energy limit, and in most of the cases, satellite (two-electron) processes dominate. In addition, it is found that in these cases, the ratio of the satellite processes (including double ionization) to the main line does not approach a limit, but increases as E.

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The electron-impact ionization cross sections are reported for neutral beryllium (Be) and its ions (Be⁺, Be2⁺, and Be3⁺) within the frameworks of the Binary Encounter Dipole (BED), Coulomb-Born Exchange (CBE), and Distorted Wave (DW) methods. The ionization cross sections have been calculated for energies ranging from the ionization threshold up to 100 eV, considering both the ground state and the first excited state of beryllium. The BED method exhibited excellent agreement with the experimental data for Be⁺ within the energy range of 52–116 eV. Furthermore, a detailed comparison has been performed between the calculated cross sections and existing theoretical and experimental data. We have additionally calculated the Maxwell rate coefficients for direct ionization in the ground state of neutral beryllium (Be) and its ions over an electron energy range extending up to 10 keV. These results provide valuable insights for plasma modeling by offering critical data for understanding the interaction dynamics of beryllium in plasma environments.

Graphical abstract

Ground state electron impact ionization cross section of Be(1s2 2s2)as a function of incident electron energy