Photoneutron Cross section of Oxygen and Aluminum

The absolute ( gamma ,n) cross sections of aluminum and oxygen have been measured using bremsstrahlung from a 70-Mev synchrotron. The O/sup 16/( gamma ,n) and Al/sup 27/( gamma ,n) cross sections are plotted to 30 Mev and compared with the resultants of Gaussian curves used to synthesize the cross sections. The values of the parameters of the Gaussian curves used to synthesize the cross sections are tabulated. Theoretical values of the energy at which the maximum cross section occurs (E/sub m/), the dipole absorption strength, and the width at half maximum of the Gaussian curve are given for O/sup 16/ and values of E/sub m/ from a total absorption experiment are given for Al/sup 27/. (H.D.R.)