Several-MeV γ-ray generation at NewSUBARU by laser Compton backscattering

A new laser Compton gamma ray source in the energy range of several-MeV was developed using a CO2 laser at the NewSUBARU electron storage ring. When the electron energies were 974, 1220 and 1460 MeV, the maximum gamma ray energies were measured to be 1.72, 2.72, and 3.91 MeV. The luminosity of the gamma rays was 7300 photon/mA/W/s and a flux of 5.8x106 photon/s was achieved. A gamma beam divergence of 0.5 mrad and its pattern were also measured. These performances agreed with calculations. This generation of gamma rays is in a no-loss mode for the storage electrons, and the maximum flux was limited only by the power of the laser. A flux of up to 1011 photon/s will be achieved using a 30 kW class CO2 laser. Several-MeV gamma ray sources at NewSUBARU are capable of generating such high power.