A real-time transverse momentum discriminator for the BABAR level 1 trigger system

The transverse momentum discriminator module (PTDM) is one of the three main modules used in the level 1 charged particle trigger system of the BABAR detector at PEP-II. It provides trigger decisions for charged particles with a transverse momentum, P/sub t/, greater than a configurable threshold. The transverse momentum discrimination algorithm works by evaluating the curvature of the charged tracks in the 1.5 T axial magnetic field. The capabilities of the PTDM are key to a stable and efficient operation of the BABAR experiment even under severe background conditions.