HERA-B: overview and 1996 engineering run

HERA-B is an experiment designed primarily to study CP violation in decays of B mesons into the “gold plated” decay mode B0 → Jψ KS0. The B mesons are produced in interactions of 820 GeV protons in the HERA proton beam with an internal wire target in the beam halo. Besides a short overview, the conception of the internal target and the results of the target tests are addressed. The detector requirements as well as the main detector components are described, whereas the physics goals of the experiment and some details of the detector are described elsewhere in this issue.