HERA-B triggering

The HERA-B collaboration intends to obtain a first measurement of CP-violation in B decay by studying B-mesons produced in proton-nucleus collisions in a wire target positioned in the halo of the 820 GeV HERA proton ring. A high interaction rate coupled with the low rate of B-meson production place particularly stringent demands on the trigger. The goals and design of the HERA-B trigger system are discussed.