Mole for Measuring SIS100 Magnets Commissioning and First Test Results

The SIS100 synchrotron utilizes fast ramped superconducting magnets operated with a frequency of 1 Hz. The beam pipe is of elliptic aperture and the dipole magnets are curved. Therefore, elliptic and toroidal multipoles were developed which allow describing the field concisely within the whole aperture. A mole (i.e., a measurement system based on a rotating coil probe with all auxiliary components operating within the magnet's field) was developed able to sustain ramp rates of up to 4 T/s. It was tested in the field of a conventional magnet and in the first SIS100 superconducting prototype magnet. We recall general design issues of the mole and describe their advantages. We present the first measurements of the mole on the SIS100 prototype and compare them to the results obtained with an independent system. We outline how the rotating coil probe measurements have to be interpreted in the curved magnet using toroidal multipoles, and possible further improvements of the system.