Measurement ofO16(γ,n)15O at medium energies

Exclusive differential cross sections for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(γ,n${)}^{15}$O process have been measured for $E_{\gamma }$=150, 200, and 250 MeV and ${\theta }_L$=49°, 59°, and 88°. This measurement is the first of its type to be reported for the energy region above the pion production threshold. An uncollimated bremsstrahlung beam was incident on an ${\mathrm{H}}_2$O target, and neutrons were measured with a recoil proton spectrometer with resolution sufficient to identify the residual ${}_{}{}^{15}{}_{}{}^{}\mathrm{O}$ ground state. The results are compared to (γ,p) data and to calculations including effects from meson exchange currents.