Preliminary Study of 4 T Superconducting Dipole for a Light Rotating Gantry for Ion-Therapy
L. Rossi, E. Benedetto, E. De Matteis, S. Farinon, E. Felcini, M. Karppinen, S. Mariotto, R. Musenich, D. Perini, Marco Prioli, M. Pullia, M. Sorbi, M. Statera, D. Tommasini, R. U. Valente
Abstract
A collaboration between CERN, CNAO, INFN, and MedAustron has been formed aiming at designing a light rotating gantry suitable for hadron therapy based on 430 MeV/n carbon ion beams. After a first design for a 3 T dipole field, as the backbone of the gantry magnetic system, now the collaboration is looking at an alternative design, for at least 4 T field with a faster ramp rate. The magnet is designed according to the cosθ layout to be wound with Nb-Ti superconducting Rutherford cable. One of the main challenges is the very small curvature radius of 1.65 m with a relatively large aperture, of 70-90 mm. Another challenge is the use of indirect cooling despite the cycling operation of 0.4 T/s. The paper reports the preliminary investigation for a 4.5 T dipole. The design will be followed by the construction of a 1 m long demonstrator to be manufactured and tested at INFN (LASA laboratory) in about three years. The conductor is a Rutherford cable of 2.6 µm Nb-Ti filament size, embedded in a Cu-Mn alloy matrix. The resulting gantry is very compact: the collaboration is working on integration between gantry structure and magnets to allow reducing the rotating weight in the range 50-80 tons, which is a factor 4 to 5 less than the present state-of-the-art.