Electron-pair creation on uranium by 10 and 20 MeV photons.

Improved corrections for inscattering and photon regeneration were made to observed total absorption cross sections of uranium reported earlier. Electron-pair creation cross sections ${\ensuremath{\sigma}}_{K}$ for 10 and 20 MeV photons on $^{238}\mathrm{U}$ were obtained from the adjusted total cross sections. Recently published theoretical values of ${\ensuremath{\sigma}}_{K}$ at these energies agree within about 1% with the revised experimental values. The discrepancy at 10 MeV was previously thought to be about 4%. The remaining discrepancy may be due to neglect of the finite size of the nucleus in the calculations, or to slightly inaccurate screening or radiative corrections.