Study on extent of fragments produced from high energy carbon beams

Production of fragment particles in a patient's body is one of the important problems on heavy ion therapy. It is required to know the fluence and the energy distribution of each fragment nuclide, so called radiation quality, to understand the biological effect of the incident beam precisely. In this study, the angular distributions of the fragment nuclei produced in thin targets were measured to derive the spatial distribution originating from projectile fragmentation reactions. In the particle identification with ΔE-TOF technique, it was difficult to evaluate the small yield of fragment particles precisely under the strong influence of the primary beam at small angles to the beam axis. ΔE-ΔE technique with an energy degrader was also examined. (author)