Coherent Bremsstrahlung at the Bepc Collider *

Coherent bremsstrahlung (CBS) is a specified type of radiation at colliders with short bunches. In the present paper we calculate the main characteristics of CBS for the BEPC collider. At this collider dN γ ∼ 3 · 10 8 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 for 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 2 x. Besides, CBS may be very useful for a fast control over an impact parameter R between the colliding bunch axes because a dependence of dN γ on R has a very specific behavior. It seems quite interesting to investigate this type of radiation at the BEPC collider (for example, in the range of a visible light with the rate about 3 · 10 14 photons per second) and to apply it for the fast beam control.