Direct measurement of the 15N(p,γ)16O total cross section at novae energies

The N-15(p,gamma)O-16 reaction controls the passage of nucleosynthetic material from the first to the second carbon-nitrogen-oxygen (CNO) cycle. A direct measurement of the total N-15(p,gamma)O-16 cross section at energies corresponding to hydrogen burning in novae is presented here. Data have been taken at 90-230 keV center-of-mass energy using a windowless gas target filled with nitrogen of natural isotopic composition and a bismuth germanate summing detector. The cross section is found to be a factor 2 lower than previously believed.