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Title: Gamow peak in thermonuclear reactions at high temperatures

Abstract

The Gamow peak represents one of the most important concepts in the study of thermonuclear reactions in stars. It is widely used in order to determine, at a given plasma temperature, the effective stellar energy region in which most charged-particle induced nuclear reactions occur. It is of importance in the design of nuclear astrophysics measurements, including those involving radioactive ion beams, and for the determination of stellar reaction rates. We demonstrate that the Gamow peak concept breaks down under certain conditions if a nuclear reaction proceeds through narrow resonances at elevated temperatures. It is shown that an effective stellar energy window does indeed exist in which most thermonuclear reactions take place at a given temperature, but that this energy window can differ significantly from the commonly used Gamow peak. We expect that these findings are especially important for thermonuclear reactions in the advanced burning stages of massive stars and in explosive stellar environments.

Authors:
; ; ;  [1];  [2];  [3];  [4]
  1. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599-3255 (United States)
  2. (United States)
  3. CSNSM, CNRS/IN2P3/UPS, Bat. 104, F-91405 Orsay Campus (France)
  4. Department of Physics, University of Cyprus, Nicosia 1678 (Cyprus)
Publication Date:
OSTI Identifier:
20995236
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevC.75.045801; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ASTROPHYSICS; CHARGED PARTICLES; DESIGN; ELECTRON TEMPERATURE; ION TEMPERATURE; PEAKS; RADIOACTIVE ION BEAMS; REACTION KINETICS; STARS; TEMPERATURE RANGE 0400-1000 K; THERMONUCLEAR REACTIONS; WINDOWS

Citation Formats

Newton, J. R., Iliadis, C., Champagne, A. E., Ugalde, C., Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308, Coc, A., and Parpottas, Y. Gamow peak in thermonuclear reactions at high temperatures. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.045801.
Newton, J. R., Iliadis, C., Champagne, A. E., Ugalde, C., Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308, Coc, A., & Parpottas, Y. Gamow peak in thermonuclear reactions at high temperatures. United States. doi:10.1103/PHYSREVC.75.045801.
Newton, J. R., Iliadis, C., Champagne, A. E., Ugalde, C., Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308, Coc, A., and Parpottas, Y. Sun . "Gamow peak in thermonuclear reactions at high temperatures". United States. doi:10.1103/PHYSREVC.75.045801.
@article{osti_20995236,
title = {Gamow peak in thermonuclear reactions at high temperatures},
author = {Newton, J. R. and Iliadis, C. and Champagne, A. E. and Ugalde, C. and Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708-0308 and Coc, A. and Parpottas, Y.},
abstractNote = {The Gamow peak represents one of the most important concepts in the study of thermonuclear reactions in stars. It is widely used in order to determine, at a given plasma temperature, the effective stellar energy region in which most charged-particle induced nuclear reactions occur. It is of importance in the design of nuclear astrophysics measurements, including those involving radioactive ion beams, and for the determination of stellar reaction rates. We demonstrate that the Gamow peak concept breaks down under certain conditions if a nuclear reaction proceeds through narrow resonances at elevated temperatures. It is shown that an effective stellar energy window does indeed exist in which most thermonuclear reactions take place at a given temperature, but that this energy window can differ significantly from the commonly used Gamow peak. We expect that these findings are especially important for thermonuclear reactions in the advanced burning stages of massive stars and in explosive stellar environments.},
doi = {10.1103/PHYSREVC.75.045801},
journal = {Physical Review. C, Nuclear Physics},
number = 4,
volume = 75,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • The Gamow-Teller (GT) transitions in the {beta}{sup +}(electron capture) direction from the ground state of {sup 56}Fe to the excited states of {sup 56}Mn play an important role in the core collapse of presupernova. Assuming that isospin analogous transitions in isobars have corresponding strengths, we deduced these GT strengths by combining the results of the {sup 56}Fe(p, p'){sup 56}Fe experiment performed at 200 MeV and 0 deg. and the {sup 56}Fe({sup 3}He, t){sup 56}Co experiment in the {beta}{beta} direction at 140 MeV/u and 0 deg. The ground state of {sup 56}Fe has the isospin value of T = 2, whilemore » the GT states in {sup 56}Mn have T = 3. In order to identify the analogous T = 2{yields}3, GT transitions in the {sup 56}Fe(p, p'){sup 56}Fe and the {sup 56}Fe({sup 3}He, t){sup 56}Co measurements, we used the fact that the isospin Clebsch-Gordan (CG) coefficients for these T = 2{yields}3 transitions are different in these measurements. Then the GT transition strengths B(GT) in the {beta}{sup +} direction can be deduced from the B(GT) values of the corresponding transitions well determined in the {sup 56}Fe({sup 3}He, t){sup 56}Co measurement assuming the isospin symmetry and correcting the difference of CG coefficients.« less
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  • The LUNA Collaboration has provided the first cross section measurements of the key reaction {sup 3}He({sup 3}He,2p){sup 4}He of the proton-proton chain at the thermal energy of the Sun. This successful project has shown that, by going underground and by using the typical techniques of the low background physics, it is possible to measure down to the energy of the nucleosynthesis inside the stars.
  • The Bordoni peak is thrown as a relaxation peak which appears at around 50K (for measuring frequency f {approximately} 1Hz) in various cold worked metals with the fcc structure. Seeger has proposed that this relaxation is associated with a kink pair formation (KPF) on dislocations. Since all the characteristics of the Bordoni peak so far observed experimentally are consistent with the KPF model, this model was widely accepted as the origin of the Bordoni peak. However, the flow stress at low temperatures expected from the temperature of the Bordoni peak is about two orders of magnitude larger than that observedmore » in the macroscopic deformation experiments. If the Bordoni peak is attributed to the KPF model, the authors have to postulate the presence of preferential deformation sites on dislocations (deformation short-circuits) to explain the very low flow stresses in fcc metals. Possible candidates for such sites might be sites at bent corners of extended dislocations, and lubrication sites. They have, however, no definite model at present. In the present work, the behavior of the Bordoni peak in zone-refined Cu was studied during annealing after cold work. In contrast to the results on the ordinary pure Cu, the Bordoni peak was found to grow during annealing even after 800 C. The results will be shown to be in excellent agreement with the KPF model.« less