[en] The ²⁸Si(p,t)²⁶Si reaction has been studied to resolve a controversy surrounding the properties of the ²⁶Si level at 5.914 MeV and its contribution to the ²⁵Al(p,γ)²⁶Si reaction rate in novae, which affects interpretations of galactic ²⁶Al observations. Recent studies have come to contradictory conclusions regarding the spin of this level (0⁺ or 3⁺), with a 3⁺ assignment implying a large contribution by this level to the ²⁵Al(p,γ)²⁶Si reaction rate. We have extended our previous study [Bardayan et al., Phys. Rev. C 65, 032801(R) (2002)] to smaller angles and find the angular distribution of tritons populating the 5.914-MeV level in the ²⁸Si(p,t)²⁶Si reaction to be consistent with either a 2⁺ or 3⁺ assignment. We have calculated reaction rates under these assumptions and used them in a nova nucleosynthesis model to examine the effects of the remaining uncertainties in the ²⁵Al(p,γ)²⁶Si rate on ²⁶Al production in novae

[en] We have developed a novel technique for measurements of low-energy (p,α) reactions using heavy-ion beams and a differentially pumped windowless gas target. We applied this new approach to study the 183 keV resonance in the ¹⁷O(p,α)¹⁴N reaction. We report a (center-of-mass) resonance energy of E_r=183.5(+0.1/-0.4) keV and a resonance strength of ωγ_pα=(1.70±0.15) meV, and we set an upper limit (95% confidence) on the total width of the state of Γ<0.1 keV. This resonance is important for the ¹⁷O(p,α)¹⁴N reaction rate, and we find that ¹⁸F production is significantly decreased in low-mass ONeMg novae but less affected in more energetic novae. We also report the first determination of the stopping power for oxygen ions in hydrogen gas near the peak of the Bragg curve (E=193 keV/u) to be (63±1)x10^-15 eV cm²