Constraining the P30(p, γ)S31 Reaction Rate in ONe Novae via the Weak, Low-Energy, β -Delayed Proton Decay of Cl31

Le résumé fourni par la source

The $^{30}\mathrm{P}(p,\ensuremath{\gamma})^{31}\mathrm{S}$ reaction plays an important role in understanding the nucleosynthesis of $A\ensuremath{\ge}30$ nuclides in oxygen-neon novae. The Gaseous Detector with Germanium Tagging was used to measure $^{31}\mathrm{Cl}$ $\ensuremath{\beta}$-delayed proton decay through the key ${J}^{\ensuremath{\pi}}=3/{2}^{+}$, 260-keV resonance. The intensity ${I}_{\ensuremath{\beta}p}^{260}=8.{3}_{\ensuremath{-}0.9}^{+1.2}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ represents the weakest $\ensuremath{\beta}$-delayed, charged-particle emission ever measured below 400 keV, resulting in a proton branching ratio of ${\mathrm{\ensuremath{\Gamma}}}_{p}/\mathrm{\ensuremath{\Gamma}}=2.{5}_{\ensuremath{-}0.3}^{+0.4}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. By combining this measurement with shell-model calculations for ${\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\gamma}}$ and past work on other resonances, the total $^{30}\mathrm{P}(p,\ensuremath{\gamma})^{31}\mathrm{S}$ rate has been determined with reduced uncertainty. The new rate has been used in hydrodynamic simulations to model the composition of nova ejecta, leading to a concrete prediction of $^{30}\mathrm{Si}$:$^{28}\mathrm{Si}$ excesses in presolar nova grains and the calibration of nuclear thermometers.

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