• C. Ohmori
  KEK, Ibaraki
• F. Méot
  CEA, Gif-sur-Yvette
• J. Pasternak
  LPSC, Grenoble

This paper presents the RF systems of RACCAM FFAG for medical applications. Design of the RF system was updated to fit short and curved straight section of the spiral FFAG in view of preserving the compactness of the spiral lattice.

• Y. Giboudot
  Brunel University, Middlesex
• F. Méot
  CEA, Gif-sur-Yvette

The Non Scaling FFAG EMMA lattice allows a important displacement of the magnets in the radial direction. From this peculiarity, interesting studies of beam dynamics can be performed comparing simulated and experimental results. Being able to study a specific resonance, choosing a certain set of parameters for the lattice is really challenging. Simulations have been done integrating particle trajectories with Zgoubi through Magnetic Field Map created with OPERA. From a chosen tune evolution, one can find the corresponding magnets' configuration required by interpolating between a various sets of Field Map. Relative position and strength of the magnets are degrees of freedom. However, summing field maps requires a special care since the real magnetic field created by two magnets is not obviously linearly dependent on each single magnet. For this reason, frequently used hard edge and fringe field models may not be accurate enough. This linearity of the magnetic field has been studied directly through OPERA finite element method solutions and further on with Zgoubi tracking results.

• F. Méot
  CEA, Gif-sur-Yvette
• F. Forest, M.J. Leray
  Sigmaphi, Vannes
• J. Pasternak
  Imperial College of Science and Technology, Department of Physics, London

Funding: Agence Nationale de la Recherche, France, contract NT05-1_41853

A prototype of a spiral lattice FFAG magnet has been constructed in the frame of the RACCAM project*. THis magnet is subject to extensive field measurements and 3-dimensional field map measurements. The properties and qualities of the magnet are assessed directly from ray-tracing, using stepwise integration, for deriving lattice parameters as tunes, chromaticities, dynamic paertures, etc. Reporting on this is the subject of the poster.

*http://lpsc.in2p3.fr/service_accelerateurs/raccam.htm

• D. Neuvéglise
  SIGMAPHI S.A., Vannes
• F. Méot
  CEA, Gif-sur-Yvette

Funding: ANR contract nb : NT05-1₄1853

This paper presents an alternative design of the magnet for the RACCAM project. The aim of this collaboration is to study and build a prototype of a scaling spiral FFAG as a possible medical machine for hadron therapy. The magnet was first designed with a variable gap to produce the desired field law B=B₀(r/r₀)^k. The key feature in the “scaling” behavior of the magnet is in getting the fringe field extent to be proportional to the radius. Although the fringe field is increasing with gap dimension, we have obtained quit constant tunes in both horizontal and vertical by using a variable chamfer. An alternative magnet design was then proposed with parallel gap and distributed conductors on the pole to create the required field variation. This solution requires about 40 conductors along the pole and much more power than the gap shaping solution. We expect a much better tune constancy even without variable chamfer. We can think about an “hybrid” magnet with parallel gap at small radii and gap shaping afterward. Such a solution could take advantages of both solutions.

• M.J. Leray, P. Bocher, B. Diougoant, F. Forest, J.L. Lancelot
  Sigmaphi, Vannes
• F. Méot
  CEA, Gif-sur-Yvette
• J. Pasternak
  LPSC, Grenoble

The paper presents the magnetic measurements of the RACCAM prototype FFAG dipole, manufactured by SIGMAPHI for the Raccam ANR Medical FFAG project. This magnet prototyping work, started early 2006, is being performed in collaboration between the IN2P3/LPSC Laboratory team and SIGMAPHI. This paper describes the magnetic measurement results and comparison with Tosca simulation.