The CDF silicon vertex trigger for B-mesons physics study

The CDF scientific program includes particularly the study of some key topics of the Standard Model: 1) constraint of the CKM matrix: CP violation in B sector (B0 → π+π-) and Bs mixing (Bs0 → Ds-π+, Bs0 → Ds-π+π-π+); 2) t-quark physics (t → Wb); and processes beyond the Standard Model - e.g., Higgs searching (MSSM) in the H → b bar b mode. All the above processes have the common feature - the presence of b-quarks (B-mesons). B hadrons of sufficiently high transverse momentum are characterized by a large mean value of distribution of the impact parameter with respect to the beam axis. That means events containing this kind of particles can be recognized and separated from non-long-lived background simply by cutting on the track's impact parameter. The upgraded CDF is equipped by the so-called Silicon Vertex Tracker (SVT), a unique electronic device for real time track reconstruction using the data from two CDF track detectors: the silicon strip vertex detector and drift chamber. The SVT is a level-2 trigger which within 10 μs reconstructs the tracks and obtains the transverse momentum (pt), azimuthal angle (φ) and impact parameter (d) with 30 μm precision. The simulation studies show the background reduction by factor 1000 for B0 π+π- by demand d > 100 μm for at least two tracks. This trigger is the first one of this sort ever used for hadron collider experiments: it enables to trigger on the secondary vertex, which opens the unique new opportunities in the heavy quark physics study. The basic logic, architecture and perspectives of SVT application are briefly described