Correction multipoles for the high current operation of the Heavy Ion Synchrotron SIS

An upgrade program is under way to fill the Heavy Ion Synchrotron SIS up to the space charge limit at injection energy (e.g., 2·10¹¹ Ne¹⁰⁺ ions and 4·10¹⁰ U⁷³⁺ ions). One part of the program entails the construction of corrector multipoles for fine tuning of the synchrotron. Four normal quadrupoles are foreseen to compensate gradient errors of the 36 main quadrupoles in the ring, while eight skew quadrupoles will be used for the correction of tilt errors of the main quadrupoles. The skew quadrupoles will also be used to improve the multiturn injection efficiency, by linear coupling of the horizontal and vertical phase spaces. Two skew sextupoles will be provided to compensate sextupole components of the short, large aperture vertical steering magnets in the ring. Two technical restrictions had to be fulfilled. First, the space occupied by the correctors must be minimal. Therefore, the correction magnets will be constructed with a number of concentrically arranged multipole correction windings in the same magnet housing. Second, these magnets must be mounted around the beam line vacuum chamber, to avoid breaking the vacuum during their installation. Different possible configurations were investigated by computer simulation with respect to their field quality. Installation of the magnets is planned for the winter shut down of 2001/2002.