Coherent bremsstrahlung at the BEPC collider
  Coherent bremsstrahlung (CBS) is a sopecific type of radiation at colliders with short bunches. In the present paper we calculate the main characteristic of CBS for the BEPC collider. At this collider $d N_\gamma \sim 3\cdot 10^8 dE_\gamma /E_\gamma $ photons of CBS will be emitted for a single collision of the beams in the energy range $E_\gamma$ smaller than 240 eV.   It seems that CBS can be a potential tool for optimazing collisions and for measuring beam parameters. Indeed, the bunch length $\sigma_z$ can be found from the CBS spectrum because critical energy $E_c \propto 1/\sigma_z$; the horizontal transverse bunch size $\sigma_x $ is related to $dN_\gamma \propto 1/\sigma_x^2$. Besides, CBS may be very useful for a fast control over an impact parameter $R$ between the colliding bunch axex because a dependence of $dN_\gamma $ on $R$ has a very specific behavior.   It seems quite interesting to investigate this type of radiation on the BEPC collider (for example, in the range of a visible light with the rate about $3 \cdot 10^{14} $ photons per second) and apply it for the fast beam control. 
Y.B.Ding, V.G.Serbo