HERA-B, an experiment to study CP violation at the HERA proton ring using an internal target

This paper discusses a dedicated fixed target experiment at the HERA proton ring with the goal to observe CP violation in the B → JψKs0 decay channel, using a detector with a highly selective trigger for lepton pairs from the Jψ decay. The precision of the asymmetry, sin 2β, is expected to reach 0.13 within one year of running.