Standalone First Level Event Selection Package for the CBM Experiment

The main focus of the CBM experiment (FAIR, Germany) is measurement of very rare probes at interaction rates of up to 10 MHz. The experiment will operate with a data flow of up to 1 TB/s and requires full on-line event reconstruction and selection at the first level trigger. A standalone First Level Event Selection (FLES) package has been developed for the CBM experiment. It contains modules for all reconstruction stages: track finding, track fitting, short lived particle finding and selection. Reconstruction of about 50 types of particle decay channels is currently implemented. The algorithms are intrinsically local and their implementation is both vectorized (SIMD) and parallelized between CPU cores. For the track reconstruction the Cellular Automaton (CA) and the Kalman filter (KF) algorithms are used, that allows to achieve a high track reconstruction efficiency of up to 97% and a track parameters quality with 1% momentum resolution. The KF particle finder has a high efficiency with an optimal signal to background ratio. The FLES package shows a strong scalability on many-core systems and a processing speed of 1700 events per second on an Intel based computer with 80 cores.