A High-pt Trigger for the Hera-b Experiment

We have constructed a high-pT trigger for the HERA-B experiment at DESY. The HERA-B experiment produces B mesons by inserting wire targets into the halo of the proton beam circulating in HERA. The high-p T trigger records events that contain tracks that have high transverse momentum with respect to the beam. Such a trigger is efficient for recording B → ππ, B → Kπ, Bs → K K, Bs → D − s π , and other topical hadronic B decays. These decays provide sensitivity to the internal angles α and γ of the CKM unitarity triangle, and they also can be used to measure or constrain the Bs-B̄s mixing parameter xs.