69 research outputs found
Doubly differential cross sections for ionization of lithium atom by protons and O ions
We consider single ionization of lithium atom in collisions with and
O projectiles. Doubly differential cross sections for ionization are
calculated within a relativistic non-perturbative approach. Comparisons with
the recent measurements and theoretical predictions are made.Comment: Submitted to the Topical Issue of Eur. Phys. J. D based on the
contributions reported on the International Conference on Many Particle
Spectroscopy of Atoms, Molecules, Clusters and Surfaces (MPS 2018), Budapest,
Hungary, 21-24 August 201
Ab initio calculations of the transition in He-, Li-, and Be-like uranium
The bound-state QED approach is applied to calculations of the transition energies in He-, Li-, and Be-like uranium. For
U and U, standard perturbation theory for a single level is
employed, while the calculations of U have required its counterpart for
quasidegenerate levels. The utilized approach merges the rigorous QED treatment
up to the second order of perturbation theory with the higher-order
electron-correlation contributions evaluated within the Breit approximation.
The higher-order screened QED effects are estimated by means of the model-QED
operator. The nuclear recoil, nuclear polarization, and nuclear deformation
effects are taken into account as well. Along with the transition energies,
their pairwise differences are calculated. The comprehensive analysis of the
uncertainties due to uncalculated effects is carried out, and the most accurate
theoretical predictions, which are in perfect agreement with available
experimental data, are obtained.Comment: 1 figure, 8 table
Relativistic calculations of the x-ray emission following the Xe-Bi collision
We study the x-ray emission following the collision of a Bi 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.Comment: 11 figures, 2 table
Relativistic calculations of the charge-transfer probabilities and cross sections for low-energy collisions of H-like ions with bare nuclei
A new method for solving the time-dependent two-center Dirac equation is
developed. The time-dependent Dirac wave function is represented as a sum of
atomic-like Dirac-Sturm orbitals, localized at the ions. The atomic orbitals
are obtained by solving numerically the finite-difference one-center Dirac and
Dirac-Sturm equations with the potential which is the sum of the exact
reference-nucleus potential and a monopole-approximation potential from the
other nucleus. An original procedure to calculate the two-center integrals with
these orbitals is proposed. The approach is tested by calculations of the
charge transfer and ionization cross sections for the H(1s)--proton collisions
at proton energies from 1 keV to 100 keV. The obtained results are compared
with related experimental and other theoretical data. To investigate the role
of the relativistic effects, the charge transfer cross sections for the
Ne^{9+}(1s)--Ne^{10+} (at energies from 0.1 to 10 MeV/u) and
U^{91+}(1s)--U^{92+} (at energies from 6 to 10 MeV/u) collisions are calculated
in both relativistic and nonrelativistic cases.Comment: 39 pages, 6 tables, 7 figure
Relativistic calculations of charge transfer probabilities in U92+ - U91+(1s) collisions using the basis set of cubic Hermite splines
A new approach for solving the time-dependent two-center Dirac equation is
presented. The method is based on using the finite basis set of cubic Hermite
splines on a two-dimensional lattice. The Dirac equation is treated in rotating
reference frame. The collision of U92+ (as a projectile) and U91+ (as a target)
is considered at energy E_lab=6 MeV/u. The charge transfer probabilities are
calculated for different values of the impact parameter. The obtained results
are compared with the previous calculations [I. I. Tupitsyn et al., Phys. Rev.
A 82, 042701 (2010)], where a method based on atomic-like Dirac-Sturm orbitals
was employed. This work can provide a new tool for investigation of quantum
electrodynamics effects in heavy-ion collisions near the supercritical regime
Relativistic calculations of the isotope shifts in highly charged Li-like ions
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.Comment: 28 page
Calculations of the binding-energy differences for highly-charged Ho and Dy ions
The binding-energy differences for and
ions with ionization degrees , , and
are calculated. The calculations are performed using the large-scale
relativistic configuration-interaction and relativistic coupled-clusters
methods. The contributions from quantum-electrodynamics, nuclear-recoil, and
frequency-dependent Breit-interaction effects are taken into account. The final
uncertainty does not exceed eV. Combining the obtained results with the
binding-energy difference for neutral atoms calculated in [Savelyev et al.,
Phys. Rev. A 105, 012806 (2022)], we get the secondary differences of the
ion-atom binding energies. These values can be used to evaluate the amount of
energy released in the electron capture process in atom
(the value), provided mass differences of highly charged ions
and is known from experiment.
The value is required by experiments on the determination of the absolute
scale of the electron neutrino mass by studying the beta-decay process.Comment: 4 pages, Jetp Lett. (2023
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