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Title: Radiative orbital electron capture by the atomic nucleus

Abstract

The rate for the photon emission accompanying orbital 1S electron capture by the atomic nucleus is recalculated. While a photon can be emitted by the electron or by the nucleus, the use of the length gauge significantly suppresses the nuclear contribution. Our calculations resolve the long standing discrepancy of theoretical predictions with experimental data for {delta}J=2 forbidden transitions. We illustrate the results by comparison with the data established experimentally for the first forbidden unique decays of {sup 41}Ca and {sup 204}Tl.

Authors:
 [1];  [2];  [3]
  1. Institute of Theoretical Physics, Warsaw University, Hoza 69, PL-00-681 Warsaw (Poland)
  2. Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)
  3. Institute of Experimental Physics, Warsaw University, Hoza 69, PL-00-681 Warsaw (Poland)
Publication Date:
OSTI Identifier:
20995328
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.055502; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; CALCIUM 41; COMPARATIVE EVALUATIONS; ELECTRON CAPTURE; ELECTRONS; FORBIDDEN TRANSITIONS; LENGTH; PHOTON EMISSION; PHOTONS; THALLIUM 204

Citation Formats

Pachucki, K., Jentschura, U. D., and Pfuetzner, M. Radiative orbital electron capture by the atomic nucleus. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.055502.
Pachucki, K., Jentschura, U. D., & Pfuetzner, M. Radiative orbital electron capture by the atomic nucleus. United States. doi:10.1103/PHYSREVC.75.055502.
Pachucki, K., Jentschura, U. D., and Pfuetzner, M. Tue . "Radiative orbital electron capture by the atomic nucleus". United States. doi:10.1103/PHYSREVC.75.055502.
@article{osti_20995328,
title = {Radiative orbital electron capture by the atomic nucleus},
author = {Pachucki, K. and Jentschura, U. D. and Pfuetzner, M.},
abstractNote = {The rate for the photon emission accompanying orbital 1S electron capture by the atomic nucleus is recalculated. While a photon can be emitted by the electron or by the nucleus, the use of the length gauge significantly suppresses the nuclear contribution. Our calculations resolve the long standing discrepancy of theoretical predictions with experimental data for {delta}J=2 forbidden transitions. We illustrate the results by comparison with the data established experimentally for the first forbidden unique decays of {sup 41}Ca and {sup 204}Tl.},
doi = {10.1103/PHYSREVC.75.055502},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Approximate probabilities of electron excitation (shakeup/shakeoff) from various atomic states during nuclear ns electron capture have been calculated in the sudden approximation, using Hartree-Fock wave functions. Total excitation probabilities are much lower than during inner-shell ionization by photons or electrons, and ns states are more likely to be excited than np states. This latter result is borne out by K..cap alpha.. x-ray satellite spectra.
  • The general properties of orbital electron capture are reviewed. Energetic considerations, radiations associated with capture (x-rays and Auger electrons), and their experimental investigation are discussed. Considering the new results on beta interaction, formulas for transition probabilities for any order of forbiddenness were calculated by the spherical tensor method and using the two-component neutrino theory with (V, A) interaction. L/K ratios were computed from the formulas, using the bound electron wave functions given by Brysk and Rose. Theoretical results were compared with the experimental data and the agreement is fairly good. K/ beta /sup +/ ratios were computed using Dzelepov's tablesmore » for the beta /sup +/ spectrum and Brysk's and Rose's functions for the K electron. For allowed and "unique" transitions the calculated values agree with experiment. (auth)« less
  • The theory of nuclear electron capture is reviewed in the light of current understanding of weak interactions. Experimental methods and results regarding capture probabilities, capture ratios, and EC/..beta../sup +/ ratios are summarized. Radiative electron capture is discussed, including both theory and experiment. Atomic wavefunction overlap and electron exchange effects are covered, as are atomic transitions that accompany nuclear electron capture. Tables are provided to assist the reader in determining quantities of interest for specific cases.
  • A fully relativistic treatment of the radiation accompanying nuclear capture of orbital electrons is presented. All effects of the electrostatic field surrounding the nucleus are taken into account. As a preliminary step, comvenient representations for the electron Green's function and initial state wave function in a Coulomb field are derived. These forms, involving Dirac operators applied to scalar fulnctions and free-particle angular eigenfunctions, are developed from the second-order Dirac equation. They are particularly useful for calculations since the procedures which make use of the properties of traces can be employed with them. With the aid of these representations the photonmore » energy spectrum and polarization associated with allowed radiative K capture are computed. Relativistic Coulomb corrections are shown to decrease the expected photon intensity significantly at all energies. Since their effect is not sensitively dependent on energy, the predicted shape of the spectrum is not greatly altered. The Coulomb field also influences the degree of polarization of the photons emitted, but has an appreciable effect only near the lower end of the spectrum. The influence of atomic screening on the capture from the K and L shells is also taken into account approximately. It is shown that screening considerably decreases the likelihood of radiative capture of all but the innermost electrons. Finally, the existing experimental evidence is reviewed and shown to agree with the theory presented. Some additional experimental tests are proposed. (auth)« less