Observation of fragmentation events caused by space radiation: Contribution to the LET spectrum as measured with CR-39 track detectors

Different approaches for the track image analysis in CR-39 detectors exposed on board the spacecraft are presented. The main attention is paid to the tracks of short range, high-LET secondary fragments. The appropriate method for the analysis and measurement of such track events is described. Detectors were irradiated on board the Russian “FOTON-M” No. 4 microgravity and bioscience research spacecraft. Chemical treatment, track scanning and data processing were carried out by Russian and Japanese research teams independently using the original approaches. The semi-automated track scanning technique and conventional track data processing were used in Japan. The manual track scanning and alternative track data processing were employed in Russia. Comparative analysis with the conventional method is carried out. The manual event analysis proved to be more informative at high-LET region. The contribution of short range secondaries to the total LET spectrum and total space radiation doses is evaluated.