INNOVATIVE DESIGN OF THE ISOCENTRIC PROTON/CARBON ION GANTRIES*

We describe an update on the design of proton/carbon gantries using the principle of the Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) accelerators. The novel design consists of the NS-FFAG cells with the final focus and scanning system above the patient. The cells are made of small superconducting combined function dipoles. The beam is transported through the gantry transport system under a fixed magnetic field covering the whole required energy range. The weight of transport elements is dramatically reduced to a total less than one ton to be compared to the 135 tons of the present Heidelberg new facility. This is due to small magnet size resulting from the extremely strong focusing and small dispersion function (150-400 MeV/u for fully stripped carbon ions). The cost reduction, ease on operation due to the fixed magnetic field, and simplified treatment, make this design very competitive to the common used designs. We also present preliminary magnet design for the fully stripped carbon application.