Measurement of the ^{13}C(α, n_{0})^{16}O Differential Cross Section from 0.8 to 6.5 MeV.

The cross section of the ^{13}C(α,n)^{16}O reaction is needed for nuclear astrophysics and applications to a precision of 10% or better, yet inconsistencies among 50 years of experimental studies currently lead to an uncertainty of ≈15%. Using a state-of-the-art neutron detection array, we have performed a high resolution differential cross section study covering a broad energy range. These measurements result in a dramatic improvement in the extrapolation of the cross section to stellar energies potentially reducing the uncertainty to ≈5% and resolving long standing discrepancies in higher energy data.

Measurement of Low-Energy Resonance Strengths in the ^{18}O(α,γ)^{22}Ne Reaction.

The ^{18}O(α,γ)^{22}Ne reaction is an essential part of a reaction chain that produces the ^{22}Ne(α,n)^{25}Mg neutron source for both the weak and main components of the slow neutron-capture process. At temperatures of stellar helium burning, the astrophysically relevant resonances in the ^{18}O(α,γ)^{22}Ne reaction that dominate the reaction rate occur at α particle energies E_{lab} of 472 and 569 keV. However, previous experiments have shown the strengths of these two resonances to be very weak, and only upper limits or partial resonance strengths could be obtained.

New Measurement of ^{12}C+^{12}C Fusion Reaction at Astrophysical Energies.

Carbon and oxygen burning reactions, in particular, ^{12}C+^{12}C fusion, are important for the understanding and interpretation of the late phases of stellar evolution as well as the ignition and nucleosynthesis in cataclysmic binary systems such as type Ia supernovae and x-ray superbursts. A new measurement of this reaction has been performed at the University of Notre Dame using particle-γ coincidence techniques with SAND (a silicon detector array) at the high-intensity 5U Pelletron accelerator. New results for ^{12}C+^{12}C fusion at low energies relevant to nuclear astrophysics are reported.