Properties of Na20, Al24, P28, Cl32, and K36 for studies of explosive hydrogen burning

C. Wrede, J. A. Clark, C. M. Deibel, T. Faestermann, R. Hertenberger, A. Parikh, H. F. Wirth, S. Bishop, A. A. Chen, K. Eppinger, B. M. Freeman, R. Krücken, O. Lepyoshkina, G. Rugel, K. Setoodehnia

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Abstract

The radiative proton-capture reactions Ne19(p,γ)Na20, Mg23(p,γ)Al24, Si27(p,γ)P28, S31(p,γ)Cl32, and Ar35(p,γ)K36 potentially influence energy generation and/or nucleosynthesis during explosive hydrogen burning in classical novae and/or type I x-ray bursts. The thermonuclear rates of these reactions are dependent on resonance energies Er=Ex-Q and strengths ωγ. The Ne20(He3,t)Na20, Mg24(He3,t)Al24, Si28(He3,t)P28, S32(He3,t)Cl32, and Ar36(He3,t)K36 reactions have been measured using a 32-MeV, He32+ beam; ion-implanted carbon-foil targets developed at the University of Washington; and the Munich Q3D magnetic spectrograph. This experiment has already yielded precision mass measurements of Na20, Al24, P28, and Cl32 [C. Wrede, Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.81.055503 81, 055503 (2010)], which are used presently to constrain the corresponding (p,γ) reaction Q values. The new Al24 and P28 masses resolve a discrepancy in the energy of the lowest-energy resonance in the Mg23(p,γ)Al24 reaction and better constrain a direct measurement of its strength. Excitation energies in Cl32 and K36 have also been measured. An important new proton-unbound level has been found at Ex=2196.9(7) keV in K36 and the uncertainties in K36 excitation energies have been reduced by over an order of magnitude. Using the new data on K36, the A=36, T=1 triplets have been reassigned. The thermonuclear Ar35(p,γ)K36 reaction rate is found to be much higher than a commonly adopted rate and this could affect energy generation in type I x-ray bursts.

Original languageEnglish
Article number035805
JournalPhysical Review C - Nuclear Physics
Volume82
Issue number3
DOIs
StatePublished - 29 Sep 2010

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