Automatic analysis system for track measurements in CR-39 detectors for radiation protection in Space purposes

Among the most important obstacle to long-term space exploration by human beings there is the health risk due to the exposure to high charge and energy ions present in the galactic cosmic rays. The shielding is the simplest solution to protect the crews but the nuclear fragmentation events modify the radiation field. In recent years alternative materials are under investigation in order to enhance the shielding properties: therefore is crucial to measure the interaction cross section because biological effects are related to the radiation quality. In this work we report the measurement of the total charge changing cross section of 1 A GeV iron ions on different targets of interest in space radiation protection. An automatic system, realized in our laboratory, was used to analyze the CR-39 detectors. The system comprises an inverted microscope with motorized stage, a CCD camera, a motion control device and the computer code TRANA written in Labview language. The code uses the Danielsson algorithm for track recognition and determines the geometrical parameters and the central brightness of the tracks. The analysis of an image (about 200 X 300 micron^2) takes 1-3 seconds, depending on the number of observed tracks. Special care is taken for couples of overlapping tracks.