PHOTO-NEUTRON REACTION IN O-17 - GROUND-STATE DIFFERENTIAL CROSS-SECTION AT 98-DEGREES

Photoneutron spectra from O17 have been obtained at bremsstrahlung end-point energies of 13.7, 16, 22, 28, and 34 MeV using the neutron time-of-flight technique. The angle between the incident photon beam and the 49.2-m flight path was 98°. From the measured spectra the differential cross section for the O17(γ,n0)O16 reaction between 5 and 33 MeV was obtained. The considerable structure in the cross section is compared with the known spectrum of levels for this nucleus compiled from previous studies using various reactions. In the region below 19 MeV, 18 resonances correspond to levels previously identified. In addition at least 12 other resonances which have not been seen previously have been observed. In the giant dipole resonance region (above 19 MeV) the present results delineate the T=12 strength. The measurement is compared to the O16(p,γ0+γ1)F17 reaction with the expected similarities observed. The measurement also is compared to 1p,2p-1h shell-model calculations. NUCLEAR REACTIONS O17(γ,n0) O16, Ex=5.0-33.0 MeV; measured photoneutron time-of-flight spectra; deduced (dσdΩ) (Ex, 98°), resonant structure; T=12 strength of the GDR. © 1979 The American Physical Society.