Photoneutron cross sections in 7Li

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90 deg have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 +- 3.9) MeV mb, while that for the first excited state is about (17.2 +- 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li. (author)