Design of a fast-stop centroid finder for Monolithic Active Pixel Sensor

The heavy-ion experiments at the Heavy Ion Research Facility in Lanzhou (HIRFL) and the future High-Intensity Heavy-Ion Accelerator Facility (HIAF) in China drives the development of Monolithic Active Pixel Sensor (MAPS) for particle tracking detectors. To reduce the data volume from the MAPS based detectors, a centroid finder that can calculate the geometric centroid of the region of the energy deposition quickly has been designed. The centroid calculation is realized by distance screening among the coordinates of the pixels in the fired region. Performance study with the data from heavy-ion experiments in HIRFL proves that the centroid finder can accurately find the centroids and reduce the data volume from the MAPS by approximately one order of magnitude.