Free-Streaming Online Tracking in CBM

A free-streaming track reconstruction method has been developed for the CBM experiment at GSI. As a reconstruction core, it uses the existing singleevent tracking based on the Cellular Automaton, but the approach to the freestreaming tracking is generic and can be can be used with various core algorithms without modification. The method processes free-streaming data by manipulating the data at the input and output of the tracking core, leaving the reconstruction core unchanged. Data is fed into the tracking algorithm in small portions in a special way that avoids any track merging between the portions. A novel algorithm enables reading data portions without explicit time sorting, ensuring efficient processing. The approach has been validated on simulated data at collision rates up to 10 MHz and was successfully applied online for the mCBM test setup during the March 2024 and February 2025 data-taking campaigns.