arXiv subjects

E. A. Konovalova

Publications and source records attributed to E. A. Konovalova.

8 recordsLinked to original sources

arXiv2021

Atomic calculations of hyperfine structure anomaly in gold

The magnetic hyperfine structure constants have been calculated for low-lying levels in neutral gold atom and gold-like ion of mercury taking into account Bohr--Weisskopf (BW) effect. BW effect is represented as a product of atomic and nuclear ($d_\mathrm{nuc}$) factors. We have calculated the atomic factors, which enable one to extract BW-correction values for far from stability gold nuclei from the experimental data. The possible uncertainty of our atomic calculations have been estimated by the comparison with the available experimental data. It has been shown that the standard single-particle approach in $d_\mathrm{nuc}$ calculation reasonably well describes experimental data for $11/2^-$ gold isomers and $3/2^+$ ground state of $\rm ^{199}Au$. At the same time, it fails to describe the hyperfine constant in $^{197}\mathrm{Au}$. This indicates the more pronounced configuration mixing in $\rm ^{197}Au$ than in $\rm ^{199}Au$.

physics.atom-ph↗

arXiv2020

Calculation of hyperfine magnetic anomaly in many-electron atoms

The precision measurements of the ratio of hyperfine structure constants for $s_{1/2}$ and $p_{1/2}$ states allow us to estimate the difference between hyperfine magnetic anomalies for these levels. We calculate the atomic factor in order to recover the absolute values of the hyperfine magnetic anomalies from their difference. Taking into account the hyperfine anomaly correction allows one to increase the accuracy of determining the g-factors of short-lived isotopes by more than an order of magnitude.

physics.atom-ph↗

arXiv2018

Calculation of francium hyperfine anomaly

The Dirac-Hartree-Fock plus many-body perturbation theory (DHF+MBPT) method has been used to calculate hyperfine structure constants for Fr. Calculated hyperfine structure anomaly for hydrogen-like ion has been shown to be in good agreement with analytical expressions. It has been shown that the ratio of the anomalies for $s$ and $p_{1/2}$ states is weakly dependent on the principal quantum number. Finally, we estimate Bohr--Weisskopf corrections for several Fr isotopes. Our results may be used to improve experimental accuracy for the nuclear $g$ factors of short-lived isotopes.

physics.atom-ph↗

arXiv2017

Calculation of thallium hyperfine anomaly

We suggest a method to calculate hyperfine anomaly for many-electron atoms and ions. At first, we tested this method by calculating hyperfine anomaly for hydrogen-like thallium ion and obtained fairly good agreement with analytical expressions. Then we did calculations for the neutral thallium and tested an assumption, that the the ratio between the anomalies for $s$ and $p_{1/2}$ states is the same for these two systems. Finally, we come up with recommendations about preferable atomic states for the precision measurements of the nuclear $g$ factors.

physics.atom-ph↗

arXiv2016

Precision calculation of energy levels for four-valent Si I

We report results of the calculation of the low-lying levels of neutral Si using a combination of the configuration interaction and many-body perturbation theory (CI+MBPT method). We treat Si I as an atom with four valence electrons and use two different starting approximations, namely $V^{N-2}$ and $V^{N-4}$. We conclude that both approximations provide comparable accuracy, on the level of 1%.

physics.atom-ph↗

arXiv2015

Correlation, Breit, and QED effects in spectra of Mg-like ions

We calculated spectra of the first six members of the Mg-like isoelectronic sequence using different approximations. The most accurate results were obtained with the configuration interaction + all order method (CI+AO), which provided relative accuracy for transition energies on the level of 0.1\%, or better. On this level of accuracy the Breit and QED corrections become important for the systems with nuclear charge $Z\gtrsim 20$. The retardation part of the Breit interaction and QED corrections for the partial waves with $l\ne 0$ are still too small to be important.

physics.atom-ph↗

arXiv2014

Sensitivity coefficients to $α$-variation for astrophysically relevant transitions in Ni II

We calculated the dependence of the transition frequencies on the fine-structure constant $α$ ($q$-factors) for Ni~II. Nickel is one of the few elements with high sensitivity to $α$-variation, whose lines are observed at high redshifts. This makes it a sensitive probe for $α$-variation on the cosmological timescale. The electronic structure of Ni II ion was treated within the configuration interaction (CI) method using Dirac-Coulomb Hamiltonian.

physics.atom-ph↗

arXiv2012

High Precision Measurements of the Pion Proton Differential Cross Section

Study of the elastic scattering can produce a rich information on the dynamics of the strong interaction. The EPECUR collaboration is aimed at the research of baryon resonances in the second resonance region via pion-proton elastic scattering and kaon-lambda production. The experiment features high statistics and better than 1 MeV resolution in the invariant mass thus allowing searches for narrow resonances with the coupling to the pi p channel as low as 5%. The experiment is of "formation" type, i.e. the resonances are produced in s-channel and the scan over the invariant mass is done by the variation of the incident pion momentum which is measured with the accuracy of 0.1% with a set of 1 mm pitch proportional chambers located in the first focus of the beam line. The reaction is identified by a magnetless spectrometer based on wire drift chambers with a hexagonal structure. Background suppression in this case depends on the angular resolution, so the amount of matter in the chambers and the setup was minimized to reduce multiple scattering. The measurements started in 2009 with the setup optimized for elastic pion-proton scattering. With 3 billions of triggers already recorded the differential cross section of the elastic pi p-scattering on a liquid hydrogen target in the region of the diffraction minimum is measured with statistical accuracy about 1% in 1 MeV steps in terms of the invariant mass. The paper covers the experimental setup, current status and some preliminary results.

hep-ex↗