Coherent Bremsstrahlung at Beijing Electron-Positron Collider

The main characteristics of coherent bremsstrahlung (CBS) for the Beijing Electron-Positron Collider are calculated. At this collider dN_γ~3 x 10⁸ dE_γ/E_γ photons of CBS will be emitted for a single collision of the beams in the energy range E_γ< 240 eV. It seems that CBS can be a potential tool for optimizing collisions and measuring beam parameters. Indeed, the bunch length σ_z can be found from the CBS spectrum because critical energy E_c ∝ 1/σ_z; the horizontal transverse bunch size σ_x is related to dN_γ∝1/σ_x². In addition, CBS may be very useful for a fast control over an impact parameter R between the colliding bunch axes.