Design Status of the FAIR Synchrotrons SIS100 and SIS300 and the High Energy Beam Transport System

Introduction The heavy ion synchrotrons SIS100 and SIS300 are the central part of the FAIR accelerator facilities. The two stage acceleration concept enables the optimisation of both synchrotrons for specific tasks, allowing a real parallel experiment supply with beams of different properties. The 1083 m long lattice of SIS100 consists of superferric magnets similar to the magnets developed for the NUCLOTRON synchrotron at JINR, Dubna [1]. This magnet technology has been chosen to minimize the cycle time by means of fast ramping with ramp rates of up to 4 T/s. At cycle times of typically 1.5 s, Uranium beams with an average intensity of 3x10 ions/s can be generated. Due to the small aperture of superferric magnets, the total pulse power does not exceed 18 MW even at maximum ramp rate. SIS100 is designed for acceleration of high intensity, low charge state heavy ion and proton beams. A powerful magnetic alloy loaded RF compression system enables the generation of short single ion bunches before extraction. SIS300 is equipped with low-loss, cos(Θ)-magnets providing ramp rates up to 1 T/s. SIS300 may be used as a stretcher ring to deliver linac-like, uninterrupted heavy ion beams of intermediate charge states for fixed target experiments or for acceleration of highly charged ions to high energies (34 GeV/u). By distributing the acceleration and extraction process over the two machines (SIS100 and SIS300) the average intensity can be considerably increased. The FAIR beam transport system contains two parallel beam lines from the synchrotrons to the production targets for radioactive secondary beams. A large number of achromatic beam transport sections, connect the three synchrotrons SIS18, SIS100 and SIS300 with the Super-Fragment Separator (Super-FRS), various areas for plasma physics, atomic physics and biophysics experiments and the antiproton production target. The primary beam production chain allows an optimal beam matching to the targets and the FAIR secondary beam facility.