The non-destructive indirect measurement of accelerator electron beam parameters is a challenging task. Both the traditional X-ray pinhole imaging methods on storage rings and optical diffraction radiation (ODR) from a slit techniques on linear accelerators have their shortcomings. The laser Compton scattering (LCS) device is a new light source that uses relativistic electrons and low-energy photons to collide with each other to produce high-energy γ beams.

This study aims to extract the SSRF (Shanghai Synchrotron Radiation Facility) electron beam parameters based on the laser Compton scattering (LCS) techniques.

Under the condition of controllable laser parameters, the electron beam parameters of LCS could be determined by the γ beam measurement. Firstly, simulation spectra reconstructed by self-developed Monte Carlo program based on Geant4 were selected by those best matched with the experimentally measured energy spectra. Then, the corresponding parameters of electron beam, including beam spot size in horizontal direction, electron energy and emittance, were extracted. Finally, the consistency of the gamma energy spectra at different colliding angles measured on the Shanghai Laser Electron Gamma Source (SLEGS) beamline station of SSRF was verified.

The extracted electron beam parameters of the SSRF storing ring are in good agreement with the theoretical values. The electron beam energy at SSRF storage ring BL03SSID interaction point is (3 511.44±0.11) MeV, the transverse (horizontal) dimension of the electron beam is (316.60±0.15) μm, and the emittance of the electron beam is (4.56±0.01) nm·rad, with relative deviations of 0.33%, 1.6%, 8.1%, respectively.

Results of this study demonstrate that LCS is an effective and non-destructive way to determine the electron beam parameters indirectly and lays a stable foundation for the extraction of other parameters of the electron beam.