Measurement of the acceptance of SIS-18 by means of a transverse RF beam excitation

We present the results of a measurement of the acceptance of SIS-18. The need for such an experiment particularly arises from the usage of the GSI synchrotron SIS-18 as a booster within the FAIR project [1, 2] including regular high-current operation. In this regime, an uncontrolled beam loss in the pipe can lead to vacuum degradation and irradiation of the machine. A precise knowledge of the acceptance will help to optimise SIS-18 to reduce particle loss. Several experiments, which used diffusion, had been performed at different accelerators to measure the acceptance or the dynamic aperture. Here, the time required for the beam edge to reach the aperture was measured, see e.g. [3, 4]. Unfortunately, the estimation of this time is unprecise because a detailed knowledge of the initial beam size is necessary which translates in a large uncertainty in the derived acceptance. In order to avoid this uncertainty we study the evolution of the particle loss after the beam edge has reached the aperture.