• O. Delferrière, D. Boutin, A. Dael, A. Drouart, C. Mayri, J. Payet, J.-M. Rifflet
  CEA, Gif-sur-Yvette

S3 (Super Separator Spectrometer) [1] is a future device designed for experiments with the very high intensity heavy ion stable beams of SPIRAL2. It will be set-up at the exit of the linear accelerator LINAG at GANIL (Caen, France). It will include a target resistant to very high intensities, a first stage momentum achromat for primary beam suppression, a second stage mass spectrometer and a dedicated detection system. This mass spectrometer includes a set of four large aperture quadrupole triplets with embedded multipolar corrections. These magnets are a combination of three multipoles which could be realized with superconductor wound in flat racetrack coils. To enable the primary beam extraction one triplet has to be opened on one side, which requires a careful design of such a multipolar magnet. This paper describes the opened multipole geometry. It is adapted to large apertures as demonstrated by Opera 3d© magnetic simulations [2], including harmonic analysis and integral field homogeneity.