Precision measurements of ²⁰Na, ²⁴Al, ²⁸P, ³²Cl, and ³⁶K for the rp-process

Explosive hydrogen burning is expected to occur in classical novae and type I x-ray bursts at temperatures up to 2 GK. Energy generation and nucleosynthesis in these events depend on the thermonuclear rates of radiative proton capture reactions involving unstable reactants. For exam- ple, the ¹⁹Ne(p,γ )²⁰Na, ²³Mg(p,γ ) ²⁴Al, ²⁷Si(p,γ )²⁸P, ³¹S(p, γ )³²Cl, and ³⁵Ar(p,γ )³⁶K reaction rates are each expected to be dominated by one or two narrow, isolated resonances whose prop- erties must be determined experimentally. First and foremost, the resonance energies must be known in order to approximate their contributions to the reaction rate and facilitate direct mea- surements with radioactive ion beams. By preparing thin ion implanted carbon foil targets at the University of Washington and measuring the ²⁰Ne( ³He,t)²⁰Na, ²⁴Mg(³He,t) ²⁴Al, ²⁸Si(³He,t)²⁸P, ³²S(³He,t)³²Cl, and ³⁶Ar( ³He,t)³⁶K reactions on them at ³² MeV with the Munich Q3D spec- trograph, we have measured the ground state masses of ²⁰Na, ²⁴Al, ²⁸P, and ³²Cl and excitation energies in ³²Cl and ³⁶K to precisions on the order of 1 keV.We discuss our improvements on the thermonuclear rates of the ²³Mg(p,γ )²⁴Al and ³⁵Ar(p,γ ) ³⁶K reactions.