ACTIVATION CROSS SECTIONS FOR C¹²(<i>p</i>, <i>pn</i>)C¹¹, O¹⁶(<i>p</i>, α)N¹³, and F¹⁹(<i>p</i>, <i>pn</i>)F¹⁸

Abstract

The activation cross sections for proton-induced nuclear reactions were studied in the region from threshold over a range of about 10 Mev proton energy. The scattering and 180°-focussing technique for proton irradiation was employed to realize improved energy resolution.The reaction O 16 (p, α)N 13 exhibited three large peaks at proton energies of 8.6 Mev, 11.3 Mev, and 14.6 Mev in the laboratory system. The maximum cross sections were 46 mb, 55 mb, and 45 mb respectively.Though not so pronounced as in the oxygen case, minor peaks in the cross section for C 12 (p, pn)C 11 + C 12 (p, d)C 11 modulated the previously smooth curve. These occurred at energies of 19.8 Mev, 20.9 Mev, and 22.2 Mev. The known excitation function for this reaction was extended from 32 Mev to 42 Mev and proved to be flat, thereby clarifying the normalization between the higher- and lower-energy regions.The irradiation of F 19 with protons to produce F 18 yielded a cross section which was a smooth function of energy, and thus differed in shape from the corresponding carbon curve.