Investigations of the MCP Detector of a Time-Of-Flight Detector for IMS at the FRS-ESR

The Isochronous Mass Spectrometry at the FRS-ESR facility at GSI can be used to perform high-precision mass measurements of exotic nuclei. The mass values are obtained from measuring the revolution time of the ions in the storage ring with a time-of-flight detector. The ions pass a thin carbon foil in the detector and release secondary electrons. These electrons are guided by electric and magnetic fields to two MCP detectors. Their number is amplified by micro channel plates and the resulting current is detected by an anode. In order to achieve an accurate time signal, the timing performance of the MCP detector is very important. The timing performance and the signal shape of the detector setup has been improved by including a new anode design. At the same time, the detector performance dependence on the magnetic field and the electron velocity inside of the MCP-detector was tested. The new detector design and the test results are presented.