Laser Compton back-scattering gamma-ray beamline on NewSUBARU

A laser-Compton scattering system is a unique and useful gamma-ray-beam source. The laser-Compton scattering gamma ray generation was tested on a synchrotron radiation facility, “NewSUBARU” at Lasti/UH. Cw Nd:YVO laser (wavelength: 1.064μm, maximum power: 5 W) was used in the experiments. Maximum energies of scattered gamma ray are 17.6 and 39.1 MeV at the operating electron energy of 1 and 1.5 GeV, respectively. Generated gamma-ray was measured and used in the shielding tunnel of 45 cm thickness concrete wall. A scintillation detector (NaI) and Ge detector were used to measure the gamma-ray spectrum and the yield. A measured gamma-ray yield of 5×103photons/s/mA/W is in agreement with calculation. A spatial distribution of gamma-ray and its dependence on a polarization of incident laser were measured using imaging plate (IP). Preliminary experiments of gamma-ray application were performed for a nuclear transmutation in the disposal of the radioactive nuclear waste and on a gamma-ray radiography for nondestructive testing of a thick subject. New radiation shielding for the gamma-ray beamline was designed for extracting the higher flux gamma-rays for application. Radiation leakage was calculated by EGS4 and MCNPX. The calculations of neutron transport are important for observation of fast neutron generated from a target sample irradiated by gamma-ray beam.