Measurement of sub threshold resonance contributions to fusion reactions: The case of the 13C(α, n)16O astrophysical neutron source

M. La Cognata, C. Spitaleri, O. Trippella, G. Kiss, G. V. Rogachev, A. M. Mukhamedzhanov, M. Avila, G. L. Guardo, E. Koshchiy, A. Kuchera, L. Lamia, S. M R Puglia, S. Romano, D. Santiago, R. Spartà

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The 13C(α, n)16O reaction is the neutron source for the main component of the s-process. It is is active inside the helium-burning shell of asymptotic giant branch stars, at temperatures a 108 K. In this temperature region, corresponding to an energy interval of 140-230 keV, the 13C(α, n)16O cross section is dominated by the-3 keV sub-threshold resonance due to the 6.356 MeV level in 17O. Direct measurements could not establish its contribution owing to the Coulomb barrier between interacting nuclei, strongly reducing the cross section at astrophysical energies. Similarly, indirect measurements and extrapolations yielded inconsistent results, calling for further investigations. The Trojan Horse Method was applied to the 13C(6Li, n16O)d quasi-free reaction to access the low as well as the negative energy region of the 13C(α, n)16O reaction. By using the generalized R-matrix approach, the asymptotic normalization coefficient (CÌ 17O(1/2+13C2 of the 6.356 MeV level was deduced. For the first time, the Trojan Horse Method and the asymptotic normalization coefficient were used in synergy. Our indirect approach lead to (CÌ 17O(1/2+13C)2 = 7.7-1.5 +1.6 fm-1, slightly larger than the values in the literature, determining a 13C(α, n)16O reaction rate slightly larger than the one in the literature at temperatures lower than 108 K, with enhanced accuracy.

Original languageEnglish
Title of host publication6th International Conference, FUSION 2014
PublisherEDP Sciences
Volume86
DOIs
Publication statusPublished - Jan 29 2015
Event6th International Conference on FUSION 2014 - New Delhi, India
Duration: Feb 24 2014Feb 28 2014

Other

Other6th International Conference on FUSION 2014
CountryIndia
CityNew Delhi
Period2/24/142/28/14

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    La Cognata, M., Spitaleri, C., Trippella, O., Kiss, 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., & Spartà, R. (2015). Measurement of sub threshold resonance contributions to fusion reactions: The case of the 13C(α, n)16O astrophysical neutron source. In 6th International Conference, FUSION 2014 (Vol. 86). [00023] EDP Sciences. https://doi.org/10.1051/epjconf/20158600023