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Present experimental constraints on the total S-factor of ^(12)C(α,γ)^(16)O and proposals for future experiments

Buchmann, L. and Azuma, R. E. and Barnes, C. A. and Humblet, J. and Langanke, K. (1997) Present experimental constraints on the total S-factor of ^(12)C(α,γ)^(16)O and proposals for future experiments. Nuclear Physics A, 621 (1-2). pp. 153-160. ISSN 0375-9474. doi:10.1016/S0375-9474(97)00229-7.

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Because of the critical importance of the ^(12)/^(16)O ratio resulting from helium burning to the later evolution of massive stars, R-matrix fits have been made to the available angular distribution data from radiative α-capture and elastic α-scattering on ^(12)C to estimate the total ^(12)C(α,γ)^(16)O rate at stellar energies. Largely primary data, i.e. energy-dependent differential cross sections, are used in the analysis with all relevant partial waves being fitted simultaneously (surface fits). It is shown that while the E1 part of the reaction is well constrained by a recent experiment on the β-delayed α-particle decay of ^(16)N only upper limits can be placed on the E2 ground state transition which we take conservatively as S_(E2)(300) <140keV b. Monte-Carlo simulations were subsequently carried out to explore what kind of future data could lead to better restrictions on S_(E2)(300). We find that improved elastic scattering data may be the best candidate for such restrictions while improving S(300) with new radiative capture data seems to be much more difficult.

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Additional Information:© 1997 Elsevier. The authors are grateful to the Queen's University group for making their primary data available before publication. We also wish to express our gratitude to E.W.Vogt for his extensive discussions of R-matrix theory. The work has been partially supported by the Natural Sciences and Engineering Research Council of Canada, and in part by Grant PHY 94-20470 and PHY 94-12818 from the U.S. National Science Foundation.
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Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
NSFPHY 94-20470
NSFPHY 94-12818
Issue or Number:1-2
Record Number:CaltechAUTHORS:20150915-072243230
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Official Citation:L. Buchmann, R.E. Azuma, C.A. Barnes, J. Humblet, K. Langanke, Present experimental constraints on the total S-factor of 12C(α,γ)16O and proposals for future experiments, Nuclear Physics A, Volume 621, Issues 1–2, 4 August 1997, Pages 153-160, ISSN 0375-9474, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60236
Deposited By: Ruth Sustaita
Deposited On:15 Sep 2015 19:14
Last Modified:10 Nov 2021 22:31

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