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Title: Folding description of the fine structure of {alpha} decay to 2{sup +} vibrational and transitional states

Abstract

We analyze {alpha}-decays to ground and 2{sup +} vibrational states in even-even nuclei by using a coupled channels formalism. The {alpha}-nucleus interaction is simulated by a double folding procedure using M3Y plus Coulomb two-body forces. Collective excitations are described by vibrations of the nuclear surface. We use a repulsive potential, with one independent parameter, in order to simulate Pauli principle and to adjust the energy of the resonant state to the experimental Q-value. The decaying state is identified with the zero nodes resonance inside the resulting pocket-like potential. We have found that the fine structure is very sensitive to the strength of the repulsive core and the vibrational parameter of the {alpha}-nucleus potential. A satisfactory agreement with existing experimental data was obtained by using the vibrational strength as a free parameter. It turns out that the inverse of this parameter is proportional to the logarithm of the hindrance factor squared. Based on this fact we have made predictions for 15 vibrational {alpha}-emitters.

Authors:
;  [1];  [2]
  1. Department of Physics, University of Jyvaeskylae, POB 35, FIN-40351, Jyvaeskylae (Finland)
  2. 'Horia Hulubei' National Institute of Physics and Nuclear Engineering, 407 Atomistilor, Magurele-Bucharest 077125 (Romania)
Publication Date:
OSTI Identifier:
20995263
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.75.054301; (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; ALPHA DECAY; COLLECTIVE EXCITATIONS; COUPLED CHANNEL THEORY; EVEN-EVEN NUCLEI; FINE STRUCTURE; PAULI PRINCIPLE; POTENTIALS; Q-VALUE; TWO-BODY PROBLEM; VIBRATIONAL STATES

Citation Formats

Peltonen, S., Suhonen, J., and Delion, D. S. Folding description of the fine structure of {alpha} decay to 2{sup +} vibrational and transitional states. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.054301.
Peltonen, S., Suhonen, J., & Delion, D. S. Folding description of the fine structure of {alpha} decay to 2{sup +} vibrational and transitional states. United States. doi:10.1103/PHYSREVC.75.054301.
Peltonen, S., Suhonen, J., and Delion, D. S. Tue . "Folding description of the fine structure of {alpha} decay to 2{sup +} vibrational and transitional states". United States. doi:10.1103/PHYSREVC.75.054301.
@article{osti_20995263,
title = {Folding description of the fine structure of {alpha} decay to 2{sup +} vibrational and transitional states},
author = {Peltonen, S. and Suhonen, J. and Delion, D. S.},
abstractNote = {We analyze {alpha}-decays to ground and 2{sup +} vibrational states in even-even nuclei by using a coupled channels formalism. The {alpha}-nucleus interaction is simulated by a double folding procedure using M3Y plus Coulomb two-body forces. Collective excitations are described by vibrations of the nuclear surface. We use a repulsive potential, with one independent parameter, in order to simulate Pauli principle and to adjust the energy of the resonant state to the experimental Q-value. The decaying state is identified with the zero nodes resonance inside the resulting pocket-like potential. We have found that the fine structure is very sensitive to the strength of the repulsive core and the vibrational parameter of the {alpha}-nucleus potential. A satisfactory agreement with existing experimental data was obtained by using the vibrational strength as a free parameter. It turns out that the inverse of this parameter is proportional to the logarithm of the hindrance factor squared. Based on this fact we have made predictions for 15 vibrational {alpha}-emitters.},
doi = {10.1103/PHYSREVC.75.054301},
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}
}
  • We analyze {alpha}-decays to ground and 2{sup +} vibrational states in even-even nuclei by using a coupled channels formalism. A satisfactory agreement with existing experimental data was obtained by using the vibrational strength as a free parameter. It turns out that the inverse of this parameter is proportional to the logarithm of the hindrance factor squared. More details of our work has been published.
  • We give a systematic analysis of {alpha} decays to low-lying 2{sup +} states in even-even nuclei. Collective excitations are considered within the spherical quasiparticle random-phase approximation. We use realistic G-matrix elements of the Bonn interaction as a residual two-body force. The only free parameters are the ratio between the isovector and isoscalar strengths and proton-neutron asymmetry. The formalism can reproduce the main experimental trends versus the excitation energy for both the B(E2) values and the {alpha}-decay hindrance factors. We reproduced most of the available data by using one common parametrization. It turns out that the fine structure of the {alpha}more » decay is more sensitive than electromagnetic transitions as a tool for investigating nuclear interaction. With the adopted parametrization, we predict B(E2) values and {alpha}-decay hindrance factors in even-even nuclei.« less
  • A microscopic description of the {alpha} decay to intruder 0{sup +}{sub 2} states of Pb isotopes in terms of proton-neutron pairing vibrations is performed. The calculated hindrance factors with respect to {alpha} transitions into the ground state are in good agreement with the available experimental data. Predictions for further measurements are given. Hindrance factors corresponding to the decay towards Po, Hg, and Pt isotopes are calculated within a simple model. The calculated quantities agree well with the experimental data, indicating that {alpha} decay is a powerful tool to precisely determine the transition from spherical to deformed shapes in the regionmore » around {ital Z}=82.« less
  • Fully relativistic formulas for the energy-level shifts arising from no-pair exchange diagrams of two transverse photons plus an arbitrary number of Coulomb photons are derived in closed form within the external potential Bethe-Salpeter formalism. {ital O}{bold (}{alpha}{sup 7}(ln{alpha}){ital mc}{sup 2}{bold )} corrections to the fine-structure splittings of helium are obtained and expressed in terms of expectation values of nonrelativistic operators. {ital O}({alpha}{sup 7}{ital mc}{sup 2}) operators from exchange diagrams are found in nonrelativistic approximation. {ital O}({alpha}{sup 6}{ital m}{sup 2}{ital c}{sup 2}/{ital M}) nucleus-electron operators contributing to the fine-structure splittings are derived. Nonrelativistic operators of {ital O}({alpha}{sup 6}{ital mc}{sup 2}) correctionsmore » to the triplet levels of helium are presented. Nonrelativistic operators of {ital O}{bold (}{alpha}{sup 6}(ln{alpha}){ital mc}{sup 2}{bold )} corrections to the helium singlet levels and to positronium {ital S} levels are derived. {ital O}({alpha}{sup 6}{ital m}{sup 2}{ital c}{sup 2}/{ital M}) hydrogen and {ital O}({alpha}{sup 6}{ital mc}{sup 2}) positronium {ital P} levels, and {ital O}{bold (}{alpha}{sup 6}(ln{alpha}){ital mc}{sup 2}{bold )} corrections of first order to positronium {ital S} levels, are calculated using the derived operators for helium, in agreement with those obtained previously by others, except for one term in corrections to positronium {ital P} levels. In addition, the {ital O}({alpha}{sup 6}{ital mc}{sup 2}) Dirac energies for hydrogenic non-{ital S} levels are exactly reproduced in a perturbative calculation. {copyright} {ital 1996 The American Physical Society.}« less