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The β-delayed α-spectrum of ^(16)N and the astrophysical aspects of the ^(12)C(α, y) ^(16)O reaction

Azuma, R. E. and Buchmann, L. and Barker, F. C. and Barnes, C. A. and D'Auria, J. M. and Dombsky, M. and Giesen, U. and Jackson, K. P. and Humblet, J. and King, J. D. and Korteling, R. G. and Langanke, K. and McNeely, P. and Powell, J. and Roy, G. and Vincent, J. and Wang, T. R. and Wong, S. S. M. and Wrean, P. R. (1995) The β-delayed α-spectrum of ^(16)N and the astrophysical aspects of the ^(12)C(α, y) ^(16)O reaction. In: ENAM '95. Éditions Frontieres , France, pp. 619-628. ISBN 978-2863321867.

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Radiative alpha-capture by ^(12)C is a key process occurring during the helium-burning phase in red giant stars, and its rate remains one of the most significant uncertainties in the nucleo-synthetic calculations for massive stars. This is largely due to the lack of precise experimental information concerning the values of the reduced α-particle widths of the J^π = 1^- and 2^+ sub-threshold states in ^(16)O to which the higher-energy radiative capture data are only weakly sensitive. Of these two states, the reduced a-width of the E_x=7.12 MeV J^π=l^- level has been predicted to have a considerable effect on the structure of the hitherto unmeasured low-energy region of the β-delayed α-particle spectrum of ^(16)N. Experiments using the TRIUMF isotope separator TISOL have been performed to measure this a-spectrum down to an energy of E_α=600 keV, utilizing a coincidence technique which also accounts completely for the detector response function. The α-spectrum, containing 10^6 counts, has been incorporated into both R- and K-matrix analyses along with the previously measured ^(12)C(α,y)^(16)O cross section and the ^(12)C+α elastic phase shifts to yield a much improved value for Sm(300) keV. In light of this new determination of S_(EI)(300), the available radiative capture data and elastic scattering phase shifts are re-analyzed, along with the β-delayed α-spectrum of ^(16)N in an attempt also to place improved limits on the S_(E2)(300) contribution to the ^(12)C(α,y)^(16)O cross section.

Item Type:Book Section
Additional Information:© 1996 Editions Frontieres.
Record Number:CaltechAUTHORS:20150915-104813214
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60252
Deposited By: Ruth Sustaita
Deposited On:15 Sep 2015 18:49
Last Modified:03 Oct 2019 08:55

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