We study the x-ray emission following the collision of a Bi$^{83+}$ ion with a neutral Xe atom at the projectile energy 70 MeV/u. The collisional and post-collisional processes are treated separately. The probabilities of various many-electron processes at the collision are calculated within a relativistic independent electron model using the coupled-channel approach with atomic-like Dirac-Fock-Sturm orbitals. The analysis of the post-collisional processes resulting in the x-ray emission is based on the fluorescence yields, the radiation and Auger decay rates, and allows to derive intensities of the x-ray emission and compare them with experimental data. A reasonable agreement between the theoretical results and the recent experimental data is observed. The role of the relativistic effects is investigated.
Photoionization cross section $sigma_{nkappa}$, asymmetry parameter $beta_{nkappa}$, and polarization parameters $xi_{nkappa}$, $eta_{nkappa}$, $zeta_{nkappa}$ of Xe and Rn are calculated in the fully relativistic formalism. To deal with the relativistic and correlation effects, we adopt the relativistic random-phase theory with channel couplings among different subshells. Energy ranges for giant emph{d}-resonance regions are especially considered.
We review the developments made during the last decade in the theory of polarization bremsstrahlung in the non-relativistic domain. A literature survey covering the latest history of the phenomenon is given. The main features which distinguish the polarization bremsstrahlung from other mechanisms of radiation are discussed and illustrated by the results of numerical calculations.
Relativistic calculations of the isotope shifts of energy levels in highly charged Li-like ions are performed. The nuclear recoil (mass shift) contributions are calculated by merging the perturbative and large-scale configuration-interaction Dirac-Fock-Sturm (CI-DFS) methods. The nuclear size (field shift) contributions are evaluated by the CI-DFS method including the electron-correlation, Breit, and QED corrections. The nuclear deformation and nuclear polarization corrections to the isotope shifts in Li-like neodymium, thorium, and uranium are also considered. The results of the calculations are compared with the theoretical values obtained with other methods.
A model operator approach to calculations of the QED corrections to energy levels in relativistic many-electron atomic systems is developed. The model Lamb shift operator is represented by a sum of local and nonlocal potentials which are defined using the results of ab initio calculations of the diagonal and nondiagonal matrix elements of the one-loop QED operator with H-like wave functions. The model operator can be easily included in any calculations based on the Dirac-Coulomb-Breit Hamiltonian. Efficiency of the method is demonstrated by comparison of the model QED operator results for the Lamb shifts in many-electron atoms and ions with exact QED calculations.
The ground-state energies of one-electron homonuclear quasi-molecules for the nuclear charge number in the range Z=1-100 at the chemical distances R= 2/Z (in a.u.) are calculated. The calculations are performed for both point- and extended-charge nucleus cases using the Dirac-Fock-Sturm approach with the basis functions constructed from the one-center Dirac-Sturm orbitals. The critical distances R_cr, at which the ground-state level reaches the edge of the negative-energy Dirac continuum, are calculated for homonuclear quasi-molecules in the range: Z=85-100. It is found that in case of U_2^{183+} the critical distance R_cr = 38.42 fm for the point-charge nuclei and R_cr = 34.72 fm for extended nuclei.
Y. S. Kozhedub
,V. M. Shabaev
,I. I. Tupitsyn
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(2014)
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"Relativistic calculations of the x-ray emission following the Xe-Bi$^{83+}$ collision"
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Yury Kozhedub Sergeevich
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