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

Beams of Carbon nuclei are used or planned to be used in various centers for cancer treatment around the world because of their therapeutic advantages over proton beams. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important to evaluate the spatial profile of their energy deposition in the tissues, hence the damage to the tissues neighboring the tumor. In this respect, 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 12C nuclei with an energy of 400MeV/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. In order to achieve the large dynamical range required for the charge measurement, the recently developed techniques of the emulsion controlled fading are used. 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.