Speaker
Description
The laser Compton slant-scattering is a key technique to achieve the energy tunability in producing gamma-ray beams at synchrotron radiation facilities operated at a fixed electron energy. A pioneering attempt was made of generating MeV gamma-ray beams in the slant-scattering at 70 – 110o in the UVSOR-II electron storage ring [1]. The Shanghai Laser Electron Gamma Source (SLEGS) is dedicated to systematically producing gamma-ray beams in the slant-scattering for international users.
An interaction chamber involving a rotating laser optical system was designed to ensure the slant-scattering of laser photons from a 100 W CO2 laser on 3.5 GeV electrons in the storage ring in the angular range of 20 - 160o, producing gamma rays in the energy range of 0.66 – 21.1 MeV with a flux of 4.8×105 – 1.5×107 photons/s [2]. The SLEGS is also equipped with a double collimator system consisting of a revolver-type coarse collimator and a camera-shutter-type fine collimator [3]. Since gamma rays produced at Eγ> Emax/2 are confined within the divergence angle 0.2 mrad, the highest energy part is selected by the double collimator system. Thus, quasi-monochromatic gamma-ray beams with an energy spread of 4.2 – 4.6 % are produced at the target position by using an aperture of 2 mm of the double collimator system. Generation of gamma-ray beams in the slant-scattering as well as in the back-scattering has been confirmed in the commissioning of the SLEGS beamline. We present the performance of the interaction chamber and the collimator system in producing gamma-ray beams in the laser Compton slant-scattering based on the commissioning and test measurements in detail.
[1] Y. Taira et al., Nuclear Inst. Methods, Phys. Res. A 652, 696-700 (2011).
[2] H.H. Xu et al., to be submitted to Nuclear Inst. and Methods in Physics Research A.
[3] Z.R. Hao et al., Nuclear Inst. and Methods in Physics Research A 1013, 165638 (2021).