Emulsion Cloud Chamber technique to measure the fragmentation of a high-energy carbon beam

Beams of Carbon nuclei are now in use or planned to be used in various centers for cancer treatment around the world. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important for evaluating of the spatial profile of their energy deposition in the tissues, hence the damage to tissues neighbouring the tumor. To this purpose, the identification of the fragmentation products is a key element. We present in this paper the charge measurement of about 3000 fragments produced by the interaction of C nuclei with an energy of 400 MeV/nucleon in a detector simulating the density of the human body. The nuclear emulsion technique is used, by means of the so-called Emulsion Cloud Chamber. The nuclear emulsions are inspected using fast automated microscopes recently developed. A charge assignment efficiency of more than 99% is achieved. The separation of Hydrogen, Helium, Lithium, Berillium, Boron and Carbon can be achieved at two standard deviations or considerably more, according to the track length available for the measurement.