Nonresonant capture cross section measurement of the ²⁹Si(p,γ)³⁰P reaction

The isotopic ratios measured in meteoritic presolar grains are a crucial tool for tracing the nucleosynthetic origin of isotopes. In the case of silicon isotopes, two important indicators to establish the origin of presolar grains are the ratios ²⁹Si/²⁸Si and ³⁰Si/²⁸Si. To constrain theoretical predictions, the rates of key nuclear reactions influencing the abundances of ²⁹Si and ³⁰Si must be well known. One such reaction is ²⁹Si(p,γ)³⁰P which plays a role in classical nova explosions. The aim of the present work is to determine the nonresonant cross section of the ²⁹Si(p,γ)³⁰P reaction, which has not been previously measured. The activation method was employed to measure the total cross section at four proton energies between Eₚ\,=\,1000 and 1430 keV. The measured cross sections were found to be significantly (a factor of 4.3\,±\,0.6) higher than those predicted by theoretical direct capture calculations, thereby impacting the reaction rates at low astrophysical temperatures, below about 30\,MK. This higher nonresonant cross section - now based on experimental data - can be used in forthcoming nucleosynthesis calculations of classical novae. As a secondary result, the ¹⁶O(p,γ)¹⁷F cross section was also obtained and found to be in good agreement with existing literature data.