Recent results using the high intensity γ-ray source facility

We describe the high intensity γ-ray source, which produces nearly monoenergetic γ-ray beams with energies ranging from 2 to 58 MeV, intensities of 105–5×108 γ/s, and 100% linear polarization. Upgrades of the facility are in progress to increase the energy range and intensity. To illustrate some of the present capabilities of the facility, we describe the measurement of total photon attenuation cross-sections to ±0.5% in the energy range 3.451–14 MeV.