Proton capture on $^{30}$P in novae: On the existence of states at $6.40$ MeV and $6.65$ MeV in $^{31}$S

TL;DR

This study uses high-resolution measurements to confirm the existence of a key $^{31}$S state affecting nova nucleosynthesis, and reports a new state potentially influencing the $^{30}$P(p,γ) reaction rate in novae.

Contribution

The paper provides experimental evidence confirming a debated $^{31}$S state and reports a previously unobserved state relevant to nova reaction rates.

Findings

Confirmed existence of the 6401 keV state in $^{31}$S.

Identified a new state at 6648 keV in $^{31}$S.

Suggested the new state impacts the $^{30}$P(p,γ) reaction near nova temperatures.

Abstract

We use a high resolution $^{32}{\rm S}(d,t)$ measurement to investigate the claimed existence of a 6401(3) keV state in $^{31}$S that may affect the $^{30}{\rm P}(p,\gamma)$ nuclear reaction rate in oxygen-neon (ONe) novae. Our data are shown to exclude the null hypothesis - that the state does not exist - with high significance. Additionally, the data also suggest the existence of a hitherto unreported state at 6648(4) keV. This state corresponds to a $^{30}{\rm P}(p,\gamma)$ resonance at $517(4)$ keV, located below the higher edge of the Gamow window for peak nova temperatures of about 0.4 GK.