The DATCON system of the Belle II experiment. Tracking and data reduction

The SuperKEKB e⁺e^- accelerator at KEK in Japan will have a luminosity which is a factor of 40 higher than the luminosity of its predecessor KEKB. The Belle II detector at SuperKEKB will contain a two-layer pixel detector at radii of 1.421 and 2.179 cm from the interaction point, based on the DEPFET (DEpleted P-channel Field Effect Transistor) technology. It is surrounded by four layers of strip detectors. Due to the high collision rate, the data rate of the pixel detector needs to by drastically reduced by an online data reduction system. The DATCON (Data Acquisition Tracking and Concentrator Online Node) system performs track reconstruction in the SVD (Strip Vertex Detector) and extrapolates to the PXD (PiXel Detector) to calculate ROI and to keep only hits in the ROI. The track reconstruction algorithm is based on a Hough transform, which reduces track finding to finding intersection points in the Hough parameter space. In this talk the employed algorithm for fast online track reconstruction on FPGA, ROI finding and the performance of the data reduction are presented.