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We present a detailed comparison of shell model calculations with inverse kinematic transfer reaction data, obtained using a radioactive beam. Experimentally extracted spectroscopic factors from the 26 Al (d , p) 27 Al reaction for both even and odd parity states are found to be exceptionally well reproduced by the shell model and a high level of consistency is observed between bound isobaric analog states in 27 Al and 27 Si , populated via (d, p) and (d, n) transfer, respectively. Furthermore, an evaluation of key resonances in the astrophysical 26 Al (p , γ) 27 Si reaction indicates that shell model calculations provide relatively accurate predictions for the existence of strong resonances and mirror nucleus comparisons appear to hold exceptionally well for proton-unbound levels. Consequently, we expect that the utilization of both techniques will likely be a very effective tool in the investigation of stellar processes outside the current reach of experiment. [ABSTRACT FROM AUTHOR]

At low stellar temperatures the energy release due to the CN cycle is regulated by its slowest reaction 14N(p,γ)15O, the rate of which strongly depends on the subthreshold resonance at Ec.m. = -504 keV, which corresponds to the 6.79 MeV state in 15O. By using the Doppler-shift attenuation method and the ³He(16O,α)15O reaction to populate the state, we obtained an upper limit on the lifetime of this state of τ < 1.8 fs [68.3% confidence level (C.L.)]. In addition we measured the lifetimes of the 6.18 and 6.86 MeV states to be τ < 2.5 and τ = 13.3-1.2+0.9 fs, respectively (68.3% C.L.), in good agreement with the literature. [ABSTRACT FROM AUTHOR]

The astrophysical s -process is one of the two main processes forming elements heavier than iron. A key outstanding uncertainty surrounding s -process nucleosynthesis is the neutron flux generated by the Ne 22 (α , n) 25 Mg reaction during the He-core and C-shell burning phases of massive stars. This reaction, as well as the competing Ne 22 (α , γ) 26 Mg reaction, is not well constrained in the important temperature regime from ∼0.2–0.4 GK, owing to uncertainties in the nuclear properties of resonances lying within the Gamow window. To address these uncertainties, we have performed a new measurement of the Ne 22 (Li 6 , d) 26 Mg reaction in inverse kinematics, detecting the outgoing deuterons and Mg 25 , 26 recoils in coincidence. We have established a new n / γ decay branching ratio of 1.14 (26) for the key E x = 11.32 MeV resonance in Mg 26 , which results in a new (α , n) strength for this resonance of 42 (11) μ eV when combined with the well-established (α , γ) strength of this resonance. We have also determined new upper limits on the α partial widths of neutron-unbound resonances at E x = 11.112 , 11.163, 11.169, and 11.171 MeV. Monte-Carlo calculations of the stellar Ne 22 (α , n) 25 Mg and Ne 22 (α , γ) 26 Mg rates, which incorporate these results, indicate that both rates are substantially lower than previously thought in the temperature range from ∼0.2–0.4 GK. [ABSTRACT FROM AUTHOR]