Active Detection and Imaging of Nuclear Materials with High-Brightness Gamma Rays

A Compton scattering γ-ray source, capable of producing photons with energies ranging from 0.1 MeV to 0.9 MeV has been commissioned and characterized, and then used to perform nuclear resonance fluorescence (NRF) experiments. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and γ-ray results are presented. The key source parameters are the size (0.01 mm2), horizontal and vertical divergence (6 x 10 mrad2), duration (10 ps), spectrum and intensity (105 photons/shot). These parameters are summarized by the peak brightness, 1.5 x 1015 photons/mm2/mrad2/s/0.1% bandwidth, measured at 478 keV. Additional measurements of the flux as a function of the timing difference between the drive laser pulse and the relativistic photo-electron bunch, γ-ray beam profile, and background evaluations are presented. These results are systematically compared to theoretical models and computer simulations. NRF measurements performed on 7Li in LiH demonstrate the potential of Compton scattering photon sources to accurately detect isotopes in situ