An ANC-Based Indirect Evaluation of the Direct-Capture Rate for Proton Capture on Silicon-26
Year: 2026
Type: article
Abstract: Radiative proton capture on 26Si, leading to the formation of 27P, is relevant to explosive hydrogen-burning nucleosynthesis because it affects the depletion pathway of 26Al. The short lifetime of 26Si, together with the very small cross sections expected in the stellar energy region, makes a direct determination of this rate experimentally difficult. For this reason, the reaction was constrained indirectly through the ANC, using the mirror neutron system associated with 26Mg and 27Mg. Measurements of the ²⁶Mg elastic-scattering channel on ¹³C and the neutron-pickup channel populating ²⁷Mg were carried out with the MDM spectrometer and its focal-plane detector system. The analysis gave a neutron ANC of C²s1/2(27Mg) = 29.19 ± 3.94 fm−1 for the ground state of 27Mg. By applying mirror symmetry, the corresponding proton ANC for 27P was obtained as C²s1/2(27P) = 1126 ± 152 fm−1, with a spectroscopic factor of 0.64 ± 0.09. RADCAP calculations then gave a zero-energy astrophysical S-factor of S(0) = (5.6 ± 0.8) × 10−2 MeV b for the direct-capture component. The deduced direct-capture rate is nearly a factor of two higher than the earlier estimate, although for T9 > 0.1 the total rate is mainly controlled by resonant capture through the lowest excited state of 27P.
Authors: Murat Dağ, Robert Tribble
Institutions: Ahi Evran University, Texas A&M University
Language: Turkish
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7204203277