SIS18 – Intensity Record with Intermediate Charge State Heavy Ions

A new development direction towards ultimate heavy ion beam intensities is being pursued at GSI for FAIR. So far, most of the heavy ion synchrotrons have been operated with high charge state heavy ions. In order to reach intensities of more than 10/U-ions per cycle [1, 2], SIS18 and SIS100 must be operated with intermediate charge state ions [3, 4]. Such a high intensity operation with intermediate charge state heavy ions has never been demonstrated elsewhere. A major upgrade program is being conducted since ten years to prepare the desired booster operation of SIS18. The specific problems coming along with the intermediate charge state operation are strong charge exchange processes by collisions with residual gas atoms, pressure bumps by ion induced desorption and corresponding self amplifying beam loss. These processes appear far below the typical space charge limits. Thus, new design concepts and new technical equipment addressing these issues had to be developed and realized. The upgrade program of SIS18 aiming for minimum ionization beam loss [5] and stable residual gas pressure conditions has been defined in 2005. Meanwhile, the fraction of this upgrade program which has been realized has resulted in a world record in accelerated number of intermediate charge state heavy ions. INTERMEDIATE CHARGE STATE HEAVY ION OPERATION Table 1: Existing and proposed heavy ion synchrotrons operated with intermediate charge state heavy ions.