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Title: Influence of protons on the capture of electrons by {sup 7}Be in the Sun

Abstract

The capture of electrons by the nucleus {sup 7}Be from the three-body initial state p+e{sup -}+{sup 7}Be in the continuum is studied. On the basis of the expansion of the three-body continuum wave function in the small parameter {epsilon}{approx_equal}(m{sub e}/m{sub p}){sup 1/2} [m{sub e} (m{sub p}) is the electron (proton) mass], the role of the protons on the electron capture is considered. The results are compared with the traditional treatment of the electron capture by the nucleus {sup 7}Be. For stars with density and temperature like in the center of the Sun the studied mechanism can make a non-negligible contribution to the capture rate.

Authors:
; ;  [1];  [2]
  1. Bogolyubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna RU-141980 (Russian Federation)
  2. (Czech Republic)
Publication Date:
OSTI Identifier:
20995140
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 3; Other Information: DOI: 10.1103/PhysRevC.75.034608; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BERYLLIUM 7; ELECTRON CAPTURE; ELECTRONS; POSITRONS; PROTONS; SUN; THREE-BODY PROBLEM; WAVE FUNCTIONS

Citation Formats

Belyaev, V. B., Tater, M., Truhlik, E., and Institute of Nuclear Physics ASCR, CZ-250 68 Rez. Influence of protons on the capture of electrons by {sup 7}Be in the Sun. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.034608.
Belyaev, V. B., Tater, M., Truhlik, E., & Institute of Nuclear Physics ASCR, CZ-250 68 Rez. Influence of protons on the capture of electrons by {sup 7}Be in the Sun. United States. doi:10.1103/PHYSREVC.75.034608.
Belyaev, V. B., Tater, M., Truhlik, E., and Institute of Nuclear Physics ASCR, CZ-250 68 Rez. Thu . "Influence of protons on the capture of electrons by {sup 7}Be in the Sun". United States. doi:10.1103/PHYSREVC.75.034608.
@article{osti_20995140,
title = {Influence of protons on the capture of electrons by {sup 7}Be in the Sun},
author = {Belyaev, V. B. and Tater, M. and Truhlik, E. and Institute of Nuclear Physics ASCR, CZ-250 68 Rez},
abstractNote = {The capture of electrons by the nucleus {sup 7}Be from the three-body initial state p+e{sup -}+{sup 7}Be in the continuum is studied. On the basis of the expansion of the three-body continuum wave function in the small parameter {epsilon}{approx_equal}(m{sub e}/m{sub p}){sup 1/2} [m{sub e} (m{sub p}) is the electron (proton) mass], the role of the protons on the electron capture is considered. The results are compared with the traditional treatment of the electron capture by the nucleus {sup 7}Be. For stars with density and temperature like in the center of the Sun the studied mechanism can make a non-negligible contribution to the capture rate.},
doi = {10.1103/PHYSREVC.75.034608},
journal = {Physical Review. C, Nuclear Physics},
number = 3,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • This paper suffers from conceptual difficulties and unjustified approximations that render its conclusions invalid. The influence of protons on electron capture by {sup 7}Be in the Sun is already included in the standard plasma screening correction to the density of thermal electrons at the {sup 7}Be nucleus needed for calculating the capture rate. Moreover, the approximation to the three-body wave function that underlies the entire argument of Belyaev, Tater, and Truhlik [Phys. Rev. C 75, 034608 (2007)] is not valid in the limit under consideration, namely when the electron and the {sup 7}Be nucleus are spatially coincident and the protonmore » is some 30 000 fm away from the other two particles.« less
  • A sample enriched in Er/sup 166/, a natural isotopic mixture, and a sample enriched in Er/sup 167/ were irradiated with neutrons. Measurements of the internal conversion electrons were made on a magnetic BETA spectrometer having a resolution of 1.3% for 20 to 300 kev electrons and 0.6% for higher energy electrons up to 2 Mev. A comparison of the spectrum due to Er/sup 168/ with that of the natural isotopic mixture shows that the electron energies in the Er/sup 167/ spectrum do not exceed st run. Concent 300 kev. The conversion lines belonging to Er/sup 167/ and Er/sup 168/ weremore » distinguished by measurements on three targets of varying isotopic composition. The relative intensities for the conversion lines in the Er/sup 168/ spectrum are tabulated. The ratio alpha /sub K// alpha /sub L/ was found to be 2.11, 3.45, and 6.4 for the 185, 285, and 816 kev transitions respectively in Er/sup 168/. The 185 and 285 kev transitions can be assigned to type E2. A scheme for the radiative transitions of the Er/sup 168/ necleus in the Er/sup 167/(n, gamma )Er/sup 168/ reaction is presented. The Er/sup 167/ spectrum showed K-, L-, and Mconversion lines for the 208 kev transition that were significantly higher than the intensities of the remaining lines in the spectrum. The ratio alpha /sub K// alpha /sub L/ = 0.69, and the ratio alpha /sub L// alpha /sub M/ = 3 450 deg C in a .7 for the 208 kev transition. (TTT)« less
  • A study, using a proportional counter, of the probability of creation of a double layer in the K shell during K capture led to the value P/sub 2/ = (1.33 plus or minus 0.15) x 10/sup -4/, the partial probability of autoionization being, P/sub eject/ = (0.78 plus or minus 0.07) x 10/sup -4/. These two values agree with the theory of Primakoff and Porter. (tr-auth)