Measurement of the -3 keV resonance in the {sup 13}C({alpha},n){sup 16}O reaction and its influence on the synthesis of s-process nuclei

Journal Article · Tue Nov 20 00:00:00 EST 2012 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.4768498· OSTI ID:22075809

La Cognata, M; Spitaleri, C; Trippella, O; Kiss, G G; Rogachev, G V; Mukhamedzhanov, A M; Avila, M; Guardo, G L; Koshchiy, E; Kuchera, A; Lamia, L; Puglia, S M. R.; Romano, S; Santiago, D; Sparta, R ^[1]; others, and

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1. Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Catania (Italy)

The {sup 13}C({alpha},n){sup 16}O reaction is the neutron source for the main component of the s-process, responsible of the production of most nuclei in the mass range 90 < A < 204. It is active inside the helium-burning shell in asymptotic giant branch stars, at temperatures < 10{sup 8} K, corresponding to an energy interval where the {sup 13}C({alpha},n){sup 16}O is effective of 140 - 230 keV. In this region, the astrophysical S(E)-factor is dominated by the -3 keV sub-threshold resonance due to the 6.356 MeV level in {sup 17}O, giving rise to a steep increase of the S-factor. Notwithstanding that it plays a crucial role in astrophysics, no direct measurements exist. Therefore, we have applied the Trojan Horse Method (THM) to the {sup 13}C({sup 6}Li,n{sup 16}O)d quasi-free reaction to achieve an experimental estimate of such contribution. For the first time, the ANC for the 6.356 MeV level has been deduced through the THM as well as the n-partial width, allowing to attain an unprecedented accuracy in the {sup 13}C({alpha},n){sup 16}O study. Though a larger ANC for the 6.356 MeV level is measured, our experimental S(E) factor agrees with the most recent extrapolation in the literature in the 140 - 230 keV energy interval, the accuracy being greatly enhanced thanks to this innovative approach.

• OSTI ID: 22075809
• Journal Information: AIP Conference Proceedings, Vol. 1498, Issue 1; Conference: Carpathian summer school of physics 2012, Sinaia (Romania), 24 Jun - 7 Jul 2012; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA REACTIONS
ASTROPHYSICS
ASYMPTOTIC SOLUTIONS
CARBON 13 TARGET
GIANT STARS
HEAVY ION REACTIONS
HELIUM BURNING
KEV RANGE
LITHIUM 6 REACTIONS
MEV RANGE
NEUTRON SOURCES
NUCLEOSYNTHESIS
OXYGEN 16
OXYGEN 17
QUASI-FREE REACTIONS
S PROCESS
SHELL MODELS
SPECTROSCOPIC FACTORS