Polarization characteristics of a secondary gamma-ray during light scattering by relativistic electrons

The polarization characteristics of a gamma beam in near perpendicular interaction geometry are investigated as an extension of studies on ruby laser photon scattering by relativistic electrons of the internal beam on the FIAN S-60 synchrotron. A theoretical analysis of the polarization is presented. The direction and degree of polarization of gamma radiation is determined experimentally by exploiting the relationship between the scattering cross section of polarized gamma quanta on the resting electrons of the detector material and the angle betwen the scattering plane and the polarization vector. Measurement of the amplitude and energy spectra are described. The experimental findings provide good qualitative confirmation of the predicted high degree of polarization of the secondary gamma beam caused by interaction between polarized photons and unpolarized relativistic electrons in the perpendicular geometry. It is possible to create quasi-monochromatic gamma beams with the required polarization characteristics that are suitable for physical research if special steps are taken to align the interacting beams and to ensure that the laser can produce pulse energy of at least 10 J over long periods.