Photoneutron cross sections for 18O

Abstract

Absolute ( γ, xn) cross sections for 18O were measured up to 33 MeV, using a quasimonoenergetic photon beam from positron annihilation in flight. The cross sections show pronounced structure in particular at energies below the main giant dipole resonance. The (γ, 2n) cross section is large in the whole energy region. The integrated total photoneutron cross section amounts to 0.53 in units of the classcial dipole sum. No pronounced isospin splitting could be observed in the photoneutron decay channel.