MeV γ-ray generation from backward Compton scattering at SPring-8

A test experimental line at SPring-8 has been constructed for the generation of backward Compton scattered (BCS) gamma-rays by head-on collision between an 8 GeV electron beam and a far-infrared (FIR) laser. For the FIR laser, we use a continuous-wave methanol laser optically pumped by a carbon dioxide (CO2) laser. The FIR laser output power achieved is 1.6 W at maximum for 118.8 mu m lasing; this value is the highest in the case of this type of laser. As a result of the direct measurement, the generated BCS gamma-ray flux was found to be about 10(3) photons/s. This value is consistent with the estimation calculated by taking into account the input laser power and the transmittance of the laser transport system. (C) 2008 Elsevier B.V. All rights reserved.