An experimental measurement of the absolute cross section for the ${\mathrm{O}}^{17}(p, \alpha ){\mathrm{N}}^{14}$ reaction has been carried out in the energy range from 490- to 1580-kev proton bombarding energy at a laboratory angle of 150°. Resonances were observed at proton energies of 518, 672, 747, 825, 927, 1096, 1101, 1247, 1274, and 1335 kev. Other level parameters were assigned where possible. The 747-kev resonance corresponds to a level in ${\mathrm{F}}^{18}$ at 6302-kev excitation which does not appear to have been previously reported. A calculation of the ratio ${\mathrm{O}}^{17}$/${\mathrm{O}}^{16}$ formed at equilibrium at various temperatures in the CNO cycle in stars is made, and it is concluded that the terrestrial material which has been processed in the CNO cycle underwent this processing at a temperature of about 17×${10}^6$ °K.

• Received 7 August 1961

DOI:https://doi.org/10.1103/PhysRev.125.347