Atomic Processes Accompanying Alpha Decay of Superheavy Nuclei
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CLEI Theory
Atomic Processes Accompanying Alpha Decay of Superheavy Nuclei V. K. Nikulin1) and M. B. Trzhaskovskaya2)* Received January 20, 2020; revised February 24, 2020; accepted February 24, 2020
Abstract—Processes involving the ionization of atomic shells and x-ray transitions in daughter nuclei and accompanying alpha decay of superheavy isotopes are considered. The probabilities for N -shell ionization 294 during the decay of isotopes entering into the tennessine (294 117 Ts) and oganesson (118 Og) alpha-decay chains are calculated. The Dirac–Fock method is used, and all multipole transitions and alpha-particle tunneling through the atomic Coulomb barrier are taken into account. The results of these calculations are analyzed and are compared with the K-, L-, and M -shell ionization probabilities. The energies of the x-ray Kα1,2 lines are calculated for superheavy elements appearing as products of alpha decay in the 294 117 Ts and 294 Og chains. The Breit interaction and higher order electrodynamic corrections are taken into account. It 118 is found that the energy of the Kα1 line of the meitnerium isotope 268 Mt agrees within 0.01 keV with the 109 results of earlier calculations. This indicates that the line observed at the GSI laboratory (Darmstadt) at an energy that is higher than the respective theoretical value by 3.2 keV does not admit an identification with the Kα1 line of 268 109 Mt. DOI: 10.1134/S106377882004016X
1. INTRODUCTION A change in the Coulomb potential of the nucleus during alpha decay, as well as the propagation of an alpha particle through atomic orbitals, disturbs the orbitals, with the result that the daughter atom originating from the alpha-decay process emits electrons of energy ranging from 1 eV to several hundred keV units. Electron emission may be associated with various atomic processes, including the ionization of atomic shells, internal conversion, and the rearrangement of atomic shells. In the present study, we consider the ionization of internal atomic shells that accompanies alpha decay. If the emitted alpha particle populates an excited nuclear level of the decay product, the subsequent deexcitation of the nucleus proceeds either via gamma-ray emission or via the process of internal conversion to the K shell. The hole arising in the K shell after conversion may be filled owing to the x-ray transitions of electrons from the L-shells. A theoretical investigation of both electron emission and x-ray transitions is of importance for interpreting the spectra obtained during the alpha decay of superheavy elements. 1)
Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, 194021 Russia. 2) Petersburg Nuclear Physics Institute, National Research Center Kurchatov Institute, Gatchina, 188300 Russia. * E-mail: [email protected]
The history of experimental and theoretical investigations of the probability for atomic-shell ionization accompanying alpha decay in atoms of heavy atoms began from the pioneering study of A.B. Migdal [1]. It was described in detai
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