Event reconstruction and selection in high-rate heavy-ion reactions in the CBM experiment at FAIR

The CBM experiment at FAIR is being designed for the study of the QCD phase diagram in the region of the high baryon chemical potential at relatively moderate temperatures, where a complex structure is predicted by modern theories. The physics program of CBM includes precision measurements of a wide set of observables that contains very rare particles like charmed hadrons, dileptons, multi-strange (anti-) hyperons, and hypernuclei. The comprehensive and systematic study of these particles including their phase-space distributions requires extremely high interaction rates of up to 10⁷ collisions per second. The complicated decay topologies of these observables prevent the use of simple hardware triggers. Therefore, the CBM collaboration is developing a free-streaming data read-out system, where each single detector signal will be provided with a time stamp, and then send to a high-performance computing farm. There, a full online (4-D) event reconstruction will be performed based on the signals from the various detector systems. Fast algorithms then will online select those events which contain candidates of particles under investigation. The status of the CBM online event reconstruction and selection procedures is discussed.