Quadrupole and octupole radiation from O16 near 39 MeV excitation

The angular distributions of cross section and analyzing power for the radiative capture reaction N15(p,0)16O have been measured at excitation energies of 35.0 and 39.0 MeV in O16. Gamma rays were detected in a large, self-shielded NaI spectrometer at eight angles from 23°to 155°. The complex reaction amplitudes associated with the capture channels leading to dipole, quadrupole, and octupole radiation have been extracted. The data at 39 MeV excitation indicate a quadrupole component E2/E1=0.1240.015, and an octupole component E3/E1=0.00510.0026. The observation of high multipolarity radiation is discussed within the context of microscopic calculations which locate large components of the isovector quadrupole and octupole resonances within this region of excitation in O16.