Study on Nuclear Fragmentation by High Speed Emulsion Read-Out System

Recent development of high speed nuclear emulsion read-out system is remarkable. Motivated by this, we started a project to apply it to studying the interactions of relativistic heavy ions in matter using HIMAC at National Institute of Radiological Sciences in Japan. We have developed the emulsion cloud chamber to study Carbon-Water interaction in the energy range from 400 MeV/n down to several 10 MeV/n. This measurement is quite important from a point of view of the heavy ion therapy. Our experimental results for total and partial charge-changing cross sections at E > 200 MeV/n agree well with the data available from past measurements. Detailed analysis by event-by-event basis is in progress. The new emulsion technology demonstrates the potential to study heavy ion fragmentation.