A new measurement of the 19F(p,g) breakout reaction to CNO cycle has been completed at the University of Notre Dame, covering energies from 200-800 keV. The sensitivity of the measurement is a significant improvement over past measurements, including measurements of sufficient accuracy to observe previously unmeasured interference terms. As part of the development for the measurements, an particle accelerator of nuclear astrophysics was refurbished and installed in the Nuclear Structure Laboratory at the University of Notre Dame. A gamma-ray detector system was designed for isolating high Q-value reactions in a strong gamma-ray background.
The new measurements decreased the resonance strengths for the 19F(p,g) reaction which decrease the stellar reaction rate by a factor of four. As 19F(p,g) represents the only possible breakout path from the cold CNO cycle, this confirmed that the CNO cycle is closed in typical stellar burning scenarios.