Real-time luminosity monitor for a B-factory experiment

A luminosity as high as 1034 cm−2 s−1 is required for a B-factory experiment. It is crucially important to have a system that measures the luminosity in real time and continuously feeds it back to the accelerator control. The zero-degree luminosity monitor (ZDLM) has been developed for this purpose. It detects and integrates photons from radiative Bhabha scattering. The design and performance of the detector are reported.