Reaction rate of the 13C(α,n)16O neutron source using the ANC of the -3 keV resonance measured with the THM

6th Nuclear Physics in Astrophysics

物理学;天文学

La Cognata, M.^1 ; Spitaleri, C.^1,2 ; Trippella, O.^1,3 ; Kiss, G.G.^1,4 ; Rogachev, G.V.^5 ; Mukhamedzhanov, A.M.^6 ; Avila, M.^5 ; Guardo, G.L.^1,2 ; Koshchiy, E.^5 ; Kuchera, A.^5 ; Lamia, L.^2 ; Puglia, S.M.R.^1,2 ; Romano, S.^1,2 ; Santiago, D.^5 ; Spartà, R.^1,2

Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali Del Sud, Catania, Italy^1

Dipartimento di Fisica e Astronomia, Università di Catania, Catania, Italy^2

Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, Dipartimento di Fisica, Università di Perugia, Perugia, Italy^3

Institute of Nuclear Research (ATOMKI), Debrecen, Hungary^4

Department of Physics, Florida State University, Tallahassee

FL, United States^5

Cyclotron Institute, Texas A and M University, College Station

TX, United States^6

关键词: Asymptotic giant branch stars;    Asymptotic normalization coefficients;    Energy interval;    Innovative approaches;    Neutron capture reaction;    Preliminary analysis;    Resonance parameters;    Trojan horse methods;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/665/1/012013/pdf
DOI  :  10.1088/1742-6596/665/1/012013

学科分类：天文学(综合)

来源: IOP

【 摘 要 】

The s-process is responsible of the synthesis of most of the nuclei in the mass range 90 ≤ A ≤ 208. It consists in a series of neutron capture reactions on seed nuclei followed by β-decays, since the neutron accretion rate is slower than the β-decay rate. Such small neutron flux is supplied by the13C(α,n)16O reaction. It is active inside the helium-burning shell of asymptotic giant branch stars, at temperatures 8K, corresponding to an energy interval 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 in17O. In this work, we have applied the Trojan Horse Method (THM) to the13C(6Li,n16O)d quasi-free reaction to extract the 6.356 MeV level resonance parameters, in particular the asymptotic normalization coefficient (ANC) (C17O(1/2+α13C)2. A preliminary analysis of a partial data set has lead to (C17O(1/2+α13C)2= 6.7+0.9-0.6fm-1, slightly larger than the values in the literature. However, the deduced13C(α, n)16O reaction rate is in agreement with most results in the literature at ∼ 108K, with enhanced accuracy thanks to our innovative approach merging together ANC and THM.