Energy measurement of relativistic electron beams by laser Compton scattering

Laser Compton scattering by relativistic electrons provides the energy information associated with electron beams in an accelerator. Determining the electron beam energy by this method depends primarily on the signal to noise (S/N) ratio associated with laser Compton scattering. In this study, we propose a method to enhance the S/N ratio by synchronous measurement with a high peak power pulsed CO₂ laser. In this method, the pulsed CO₂ laser provides the gate trigger signals, and the delay times of the triggers are optimized to obtain a maximum S/N ratio. In the storage ring of Taiwan Light Source, a {γ} ray with the highest energy of 3.021 MeV was backscattered after the 0.1172 eV CO₂ laser photons colliding with the relativistic electrons. The S/N ratio is about 42.5 with the electron beam current being 19 mA. Also, the measured electron beam energy is 1.3058 GeV with relative uncertainty 0.13%. {} 1996 The American Physical Society.