Efficient initiation of photonuclear reactions using quasimonoenergetic electron beams from laser wakefield acceleration

Pulses of nearly monoenergetic relativistic electrons have been generated by laser wakefield acceleration and used to perform photonuclear activation of carbon, copper, and photofission in uranium. Using bremsstrahlung converter targets, the electron beams generated by this technique have been shown to be effective in producing high energy γ -rays (tens of MeV) that are necessary to efficiently induce photonuclear reactions. Quantitative γ -ray spectroscopy of the irradiated C, Cu, and U samples indicates that more than 105 reactions were produced per joule of laser energy. The activation yield measurements have been compared with Monte Carlo modeling of electromagnetic cascade and photonuclear processes occurring in the targets to infer the characteristics of the laser accelerated electron beams.