Photoprotons from carbon

Abstract

The angular and energy distributions of photoprotons from C 12 have been measured from 6.75 to 21 MeV proton energies with an E, d E/d x coincidence-counting spectrometer and with 65 MeV maximum gamma-ray energy. The spectrometer consisted of a CsI(Tl) crystal as the E detector and a silicon p-n junction diode as the d E/d x detector. The data were analysed in 1 MeV intervals, and the equation for electric dipole-electric quadrupole interference in a direct interaction − a + b sin 2 θ + A cos θ + B sin 2 θ cos θ — fitted to the data of each energy bin by the least-squares method. The results indicate that the direct interaction model with E1–E2 interference gives a good description of the interaction, with the magnitude of the interference increasing with increasing proton energy. The energy spectra show the existence of a small resonance near 13 MeV proton energy.