Proton-threshold states in27Al and the production of 27Al at low stellar temperatures

doi:10.1016/0375-9474(90)93352-7

Nuclear Physics A

Volume 512, Issue 2, 1990, Pages 317-332

https://doi.org/10.1016/0375-9474(90)93352-7 Get rights and content

Abstract

The ²⁶Mg(³He, d)²⁷Al reaction has been employed to measure excitation energies and proton spectroscopic factors for states corresponding to ²⁶Mg + p resonances in the vicinity of the proton-capture threshold. The width ratio Γ_γ/Γ was measured for three previously established resonances via a study of the ²⁶Mg(³He, dγ)²⁷Al reaction, and corresponding values of the proton widths were obtained. Combining this information establishes strengths for four of the states lying within 150 keV of the proton threshold. A ²⁶Mg + p reaction rate is deduced, and its astrophysical implications are discussed.

References (24)

W.A. Mahoney et al.
Astrophys. J.
(1984)
G.H. Share et al.
Astrophys. J.
(1985)
C.J. MacCallum et al.
Astrophys. J.
(1987)
P. von Ballmoos et al.
Astrophys. J.
(1987)
K. Elix et al.
Z. Phys.
(1979)
A.E. Champagne et al.
Nucl. Phys.
(1989)
A.A. Rollefson et al.
Nucl. Phys.
(1990)
Ch. Iliadis, C. Rolfs, U. Schröder, E. Somorjai, H.P. Trautvetter, K. Wolke, P.M. Endt, S. Kikstra and A.E. Champagne,...
R. Timmermann et al.
Nucl. Phys.
(1988)
A.E. Champagne et al.
Nucl. Phys.
(1988)

P.M. Endt et al.

Nucl. Phys.

(1978)

L. Buchmann et al.

Z. Phys.

(1980)

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^*: Work supported in part by the National Science Foundation and in part by the U.S. Department of Energy.

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Proton-threshold states in27Al and the production of 27Al at low stellar temperatures*

Abstract

Astrophys. J.

Astrophys. J.

Astrophys. J.

Astrophys. J.

Z. Phys.

Nucl. Phys.

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Proton-threshold states in²⁷Al and the production of ²⁷Al at low stellar temperatures*