Atomic Data and Nuclear Data Tables最新文献

A new set of radiative parameters (oscillator strengths and transition probabilities) was obtained for the most intense spectral lines in Re III, Re IV and Re V ions. These parameters were calculated using two independent methods, namely the pseudo-relativistic Hartree–Fock approach including core-polarization effects (HFR+CPOL) and the fully relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) approach. Detailed comparisons between the results obtained from these two methods as well as with the few data available in the literature allowed us to estimate the precision of the calculations carried out. The radiative parameters reported in the present paper concern a total of 368 electric dipole (E1) transitions in Re III, Re IV and Re V covering the ultraviolet spectral region from 655 to 2135 Å. These are of great interest for the analysis of spectra emitted by plasmas in nuclear fusion reactors, such as ITER where rhenium can be produced by neutron bombardment of the tungsten divertor wall, as well as for the investigation of astrophysical spectra observed from chemically peculiar stars or from kilonovae where rhenium can be produced by the nucleosynthesis r-process.

An overview of the current status of electron-impact excitation and ionization cross sections for Be II is given and the recommended data sets for use in plasma modeling are presented. Accurate cross sections between the lowest 14 atomic terms of $1s^{2}nl(n\le 5)$ configurations are calculated with the convergent close-coupling (CCC) method and compared with the available experimental and theoretical results. The recommended electron-impact excitation and ionization cross sections are represented by analytical fitting functions that preserve correct asymptotic behavior. Uncertainties in the recommended data sets are determined by assessing the accuracy of the target structures, the convergence in the subsequent collisional calculations, and the fitting method. They are well within 15 % for most of the transitions. The fitting coefficients for 91 excitation cross sections and 14 ionization cross sections are provided for use in plasma modeling simulations.

Theoretical photoionization cross-sections for average of configuration terms of valence ns- and np- shells of atoms C, N, O, F, Ne, Si, P, S, Cl and Ar are calculated with account for intrachannel and interchannel interactions for the energy region from threshold to 400 eV. The many-electron effects were accounted for within the framework of RPAE (random phase approximation with exchange) method, which is extended for average terms of unfilled shells. Calculations demonstrate for open-shell atoms similar effects as that were known for noble gas atoms Ne and Ar, namely a strong decrease of photoionization cross-sections of ns- subshell due to the interaction of transitions $ns\to \epsilon p$ and $np\to \epsilon d$.

The differential cross sections for the N(⁴S)-H(²S), N(⁴S)-H${}^{+}$ and N${}^{+}$(³P)-H(²S) elastic collisions were calculated and reported in the energy range of $10^{-4}$–3.7 hartree for the studies of transport properties of ionized gases with the Boltzmann equation.

They were verified by comparison with the integrated and momentum-transfer cross sections. The importance of appropriate grid of angles and possibility of neglecting the smallest phase shifts are discussed.

Davidson et al. has extended Seeger’s mass formula to non-zero excitation energies by introducing temperature-dependent coefficients in the liquid drop energy part of the semi-empirical mass formula, but did not consider the nuclear shape and shell effects. The semi-empirical mass formula of Davidson et al. is applicable for nuclear temperatures less than or equal to 4 MeV. The mass excess calculated using this mass formula with/without nuclear shape and shell effects does not reproduce the ground state mass excesses of the new atomic mass evaluation data AME2020 and/or FRDM(2012) with its coefficients at zero temperature. So, the coefficients of the semi-empirical mass formula with nuclear shape and shell effects are required to be tuned to reproduce the ground state mass excess of all the nuclei available in the recent atomic mass evaluation data AME2020 and/or FRDM(2012). The bulk and neutron–proton asymmetry coefficients of the semi-empirical mass formula of Davidson et al., including the nuclear shape and shell effects, have been tuned to reproduce the mass excess data for all known 9420 nuclei which include all the nuclei of AME2020 (Z $=$ 1-118 and A $=$ 1-295) and of FRDM(2012) (Z $=$ 8-136 and A $=$ 16-339, except 3456 nuclei which are also available in the AME2020 data) at zero temperature. The tuned bulk and neutron–proton asymmetry coefficients reproduce the ground state mass excess of the new atomic mass evaluation data AME2020 and/or FRDM(2012) within a difference of less than 1 MeV and can be used for the applications/investigations in the areas of physics where high energies are experienced or nuclei involved are in excited states, e.g., fusion–evaporation and fusion–fission processes in heavy-ion reactions. The mass excess calculated for the excited states of nuclei is compared with the excited state mass excess of the NUBASE2020 evaluation data and is in good agreement with it.

Excitation energies, transition parameters and lifetimes for 255 levels with $n$ $\le$ 4 configurations of B-like Xe${}^{49+}$ are calculated using the fully relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) method. Hyperfine structure constants, isotope shift and Landé $g_J$ factors are computed for the $2s^{2}2p,2s2p^2$ and $2p^3$ levels. The contribution of the Breit interaction and QED effects, mainly self-energy and vacuum polarization corrections, on these levels is also investigated. The uncertainties in the lifetimes and line strengths are computed, and transitions are classified according to the NIST accuracy nomenclature. A comparison with the previously available results is also carried out. This study provides extensive results for B-like Xe${}^{49+}$, which are useful for plasma diagnosis.

Experimental isomeric ratios of light (A $\le$ 4) particle-induced nuclear reactions were compiled for the product nuclides having metastable states with half-lives longer than 0.1 s. The experimental isomeric ratio data were taken from the EXFOR library and reviewed. When an experiment reports isomer production cross sections instead of isomeric ratios, the cross sections taken from the EXFOR library were converted to the isomeric ratios by us. During compilation, questionable data (e.g., preliminary data compiled in EXFOR in parallel with their final data, sum of isomer production cross sections larger than the total production cross sections) were excluded. As an application of the new compilation, goodness-of-fit was studied for the isomeric ratios predicted by the reaction model code TALYS-1.96. A text file and plots of the compiled isomer production cross sections and isomeric ratios are provided as supplemental materials.