Material emitted as ejecta from ONe novae outbursts is observed to be rich in elements as heavy as Ca. The bottleneck for the synthesis of elements beyond sulphur is the ${}^{30}\mathrm{P}(p,\gamma ){}^{31}\mathrm{S}$ reaction. Its reaction rate is, however, not well determined due to uncertainties in the properties of key resonances in the burning regime. In the present study, gamma-ray transitions are reported for the first time from all key states in ${}^{31}\mathrm{S}$ relevant for the ${}^{30}\mathrm{P}(p,\gamma ){}^{31}\mathrm{S}$ reaction. The spins and parity of these resonances have been deduced, and energies have been measured with the highest precision to date. The uncertainty in the estimated ${}^{30}\mathrm{P}(p,\gamma ){}^{31}\mathrm{S}$ reaction rate has been drastically reduced. The rate using this new information is typically higher than previous estimates based on earlier experimental data, implying a higher flux of material processed to high-$Z$ elements in novae, but it is in good agreement with predictions using the Hauser-Feshbach approach at higher burning temperatures.

• Received 9 March 2012

DOI:https://doi.org/10.1103/PhysRevLett.108.262502