Thermonuclear reaction rate of $^{29}$Si(p,$\gamma$)$^{30}$P

TL;DR

This study refines the thermonuclear reaction rate of $^{29}$Si(p,$$)$^{30}$P, crucial for understanding silicon isotope production in classical novae, by providing improved resonance data and reduced uncertainties at relevant temperatures.

Contribution

The paper presents new experimental data on resonance energies and strengths for the $^{29}$Si(p,$$)$^{30}$P reaction, significantly reducing uncertainties in reaction rates used in nova nucleosynthesis models.

Findings

Identified a new resonance at 303 keV.

Set an upper limit for the resonance at 215 keV.

Provided improved reaction rates with reduced uncertainties at T  140 MK.

Abstract

The thermonuclear rate of the $^{29}$Si(p,$\gamma$)$^{30}$P reaction impacts the $^{29}$Si abundance in classical novae. A reliable reaction rate is essential for testing the nova paternity of presolar stardust grains. At present, the fact that no classical nova grains have been unambiguously identified in primitive meteorites among thousands of grains studied is puzzling, considering that classical novae are expected to be prolific producers of dust grains. We investigated the $^{29}$Si $+$ $p$ reaction at center-of-mass energies of $200$ $-$ $420$~keV, and present improved values for resonance energies, level excitation energies, resonance strengths, and branching ratios. One new resonance was found at a center-of-mass energy of $303$ keV. For an expected resonance at $215$~keV, an experimental upper limit could be determined for the strength. We evaluated the level structure near the proton threshold, and present new reaction rates based on all the available experimental information. Our new reaction rates have much reduced uncertainties compared to previous results at temperatures of $T$ $\ge$ $140$~MK, which are most important for classical nova nucleosynthesis. Future experiments to improve the reaction rates at lower temperatures are discussed.