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The 33 S(p,γ ) 34 Cl reaction is important for constraining predictions of certain isotopic abundances in oxygenneon novae. Models currently predict as much as 150 times the solar abundance of 33 S in oxygen-neon nova ejecta. This overproduction factor may vary by orders of magnitude due to uncertainties in the 33 S(p,γ ) 34 Cl reaction rate at nova peak temperatures. Depending on this rate, 33 S could potentially be used as a diagnostic tool for classifying certain types of presolar grains. Better knowledge of the 33 S(p,γ ) 34 Cl rate would also aid in interpreting nova observations over the S-Ca mass region and contribute to the firm establishment of the maximum endpoint of nova nucleosynthesis. Additionally, the total S elemental abundance which is affected by this reaction has been proposed as a thermometer to study the peak temperatures of novae. Previously, the 33 S(p,γ ) 34 Cl reaction rate had only been studied directly down to resonance energies of 432 keV. However, for nova peak temperatures of 0.2-0.4 GK there are seven known states in 34 Cl both below the 432-keV resonance and within the Gamow window that could play a dominant role. Direct measurements of the resonance strengths of these states were performed using the DRAGON (Detector of Recoils And Gammas of Nuclear reactions) recoil separator at TRIUMF. Additionally two new states within this energy region are reported. Several hydrodynamic simulations have been performed, using all available experimental information for the 33 S(p,γ ) 34 Cl rate, to explore the impact of the remaining uncertainty in this rate on nucleosynthesis in nova explosions. These calculations give a range of ≈20-150 for the expected 33 S overproduction factor, and a range of ≈100-450 for the 32 S/ 33 S ratio expected in ONe novae.

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The 13 C( 7 Li, 6 He) 14 N0,1 reactions were measured at E( 7 Li) = 34 MeV with the Q3D magnetic spectrometer of the HI-13 tandem accelerator, and the first peaks of the angular distributions were obtained for the first time. The 14 N0,1 proton spectroscopic factors were extracted to be 0.67 ± 0.09 and 0.73 ± 0.10, respectively. Using the 13 C(p, γ) 14 N direct capture S dc (E) factors derived by the spectroscopic factors, the direct measurement data for both 1 − and 0 − resonances were well fitted via updating the resonance parameters, and then the total astrophysical 13 C(p, γ) 14 N S(E) factors and reaction rates were determined at stellar energies. The present work offers an independent examination to the existing results of the 13 C(p, γ) 14 N reaction.