Image data analysis for the NA35 streamer chamber

Abstract In the collision of relativistic heavy ions with nuclear targets at the CERN SPS up to several hundred charged particles in the momentum range of 0.1–200 GeV/ c are produced. These events have been recorded on film by the NA35 streamer chamber. A computer environment for the analysis of this data was developed and became operational at the University of Frankfurt. This Frankfurt Image Processing System (FIPS) is a modular und distributed system allowing the application of image processing and image understanding techniques to digitized streamer chamber images as well as the interactive computer-assisted measurement of photographic streamer chamber pictures on traditional film projection tables. Automatic track reconstruction software has been developed which in turn utilizes a multitude of image processing and image understanding techniques. The efficiency of the pattern recognition and track reconstruction processes is greater than 95% with a very good momentum resolution d P/P = ”(0.0009P) 2 + (0.0018) 2 . So far about 20 000 of these events have been processed. Currently approximately 50 events per day are automatically analysed.