Astrophysical S factor for the radiative capture 12N(p,gamma)13O determined from the 14N(12N,13O)13C proton transfer reaction

TL;DR

This study uses transfer reactions to determine the astrophysical S factor for the 12N(p,gamma)13O reaction, providing key data for stellar nucleosynthesis models involving Population III stars.

Contribution

The paper introduces a novel application of the ANC method with transfer reactions to accurately measure the S factor for a key astrophysical reaction on the proton drip line.

Findings

Determined the ANC for 13O -> 12N + p as 2.53 +/- 0.30 fm^-1.

Calculated the astrophysical S factor at zero energy as 0.33(4) keVb.

Found an enhanced total S factor of 0.42(5) keVb due to interference effects.

Abstract

The cross section of the radiative proton capture reaction on the drip line nucleus 12N was investigated using the Asymptotic Normalization Coefficient (ANC) method. We have used the 14N(12N,13O)13C proton transfer reaction at 12 MeV/nucleon to extract the ANC for 13O -> 12N + p and calculate from it the direct component of the astrophysical S factor of the 12N(p,gamma)13O reaction. The optical potentials used and the DWBA analysis of the proton transfer reaction are discussed. For the entrance channel, the optical potential was inferred from an elastic scattering measurement carried out at the same time with the transfer measurement. From the transfer, we determined the square of the ANC, C^2(13Og.s.) = 2.53 +/- 0.30 fm-1, and hence a value of 0.33(4) keVb was obtained for the direct astrophysical S factor at zero energy. Constructive interference at low energies between the direct and resonant captures leads to an enhancement of Stotal(0) = 0.42(5) keVb. The 12N(p,gamma)13O reaction was investigated in relation to the evolution of hydrogen-rich massive Population III stars, for the role that it may play in the hot pp-chain nuclear burning processes, possibly occurring in such objects.