Energy Calibration of the NewSUBARU Storage Ring for Laser Compton-Scattering Gamma Rays and Applications

Using γ-ray beams produced in the inverse Compton scattering between CO₂ laser photons and relativistic electrons, we have calibrated electron beam energies in the nominal energy range 550-974 MeV at the synchrotron radiation facility New-SUBARU. The laser Compton-scattering (LCS) γ-ray beams were produced at energies from 561 to 1728 keV and detected with a high-purity germanium detector. The electron beam energies were determined by reproducing the full energy peaks of the γ-ray beams by Monte Carlo simulations. The accuracy of the calibration is (5.5 - 9.4) ×10 ^{- 5}. The reproducibility of the electron beam energy is excellent in an independent injection and deceleration. The present energy calibration of the electron beams offers a standard for the energy calibration of high-energy LCS γ-ray beams produced with a Nd:YVO₄ laser. As applications of the energy calibration, we investigated the energy linearity of a 3.5^´´ × 4.0^´´ LaBr₃(Ce) detector in the response to γ-rays at energies up to 10 MeV and the energy profile of the high-energy LCS γ-ray beams.