On-line use of the 168/E emulator at the CERN ISR SFM detector

The Split Field Magnet Detector at the CERN ISR has been used in recent years to study events with a high transverse momentum charged particle. As a first level computer based trigger a linear estimate of the track momentum by fixed point arithmethic was calculated on-line by a minicomputer. In addition appreciable further rejection was obtained by off-line filtering on the IBM-370/168, using pattern recognition and a fit of the triggering particle in the magnetic field. The availability of the 168/E emulator makes it possible to transfer the proven methods used off-line to real time data reduction. Preliminary results on filter efficiency and speed for an experiment triggering on a high Psub(T) hadron at 10 to 200 with respect to the outgoing beam (Exp. R 419) are given. Possible improvements and extensions are discussed. (orig.)