Structure of S30 with S32(p,t)S30 and the thermonuclear P29(p,γ)S30 reaction rate

The structure of proton unbound S30 states is important for determining the P29(p,γ)S30 reaction rate, which influences explosive hydrogen burning in classical novae and type I x-ray bursts. The reaction rate in this temperature regime had been previously predicted to be dominated by two low-lying, unobserved, Jπ= 3+ and 2+ resonances above the proton threshold in S30. To search for these levels, the structure of S30 was studied using the S32(p,t)S30 transfer reaction with a magnetic spectrograph. We have confirmed a previous detection of a state near 4700 keV, which had tentatively been assigned Jπ=3+. We have also discovered a new state at 4814(3) keV, which is a strong candidate for the other important resonance (Jπ=2+). The new P29(p,γ)S30 reaction rate is up to 4–20 times larger than previously determined rates over the relevant temperature range. The uncertainty in the reaction rate due to uncertainties in the resonance energies has been significantly reduced.