Ranger { a Pattern Recognition Algorithm for the Hera-b Main Tracking System Part I: the Hera-b Pattern Tracker

A pattern recognition strategy for the HERA-B main tracking system is presented. A concurrent track evolution algorithm has been developed to select the optimal track candidate compatible with a seed. Intrinsically a local method, it combines the virtues of track following procedures with the necessary ability to optimize between many available paths in a high occupancy environment. The problem of hit-location in a multiplanar detector geometry is solved with an approach called domain navigation. This note gives a detailed description of the algorithm and shows its performance, which has been evaluated using HERA-B Monte Carlo events with full detector simulation and the current spectrometer geometry implementation, which is already quite realistic.