Triggering on B-Jets at CDF II

In this paper we present a trigger algorithm able to select online events enriched of $b$-jets. This feature is of central interest in order to extend the physics reach for Standard Model and Minimal Super Symmetric Model Higgs decaying into a pair of $b$-quarks. The algorithm fully exploits the recently upgraded CDFII tracking system and Level 2 CALorimeter cluster finder. These upgrades are necessary to cope with Tevatron increasing luminosity and provide new and refined trigger primitives that are the key elements of our algorithm together with the already existing Silicon Vertex Trigger. A $b$ -hadron can travel some millimeters before decaying and the trigger algorithm exploits this characteristic by searching for tracks displaced with respect to the primary vertex and matched to energetic jets of particles. We discuss the study and the optimization of the algorithm, its technical implementation as well as its performance. The new trigger provides an efficient selection for Higgs decaying into a pair of $b$-quarks and runs up to high luminosity with an acceptable occupancy of the available bandwidth.