Towards multi-hit readout of TPCs for exotic beam tracking

The Super-FRS beam diagnostics system supports the set up and adjustment of the separator and provides tracking and event-by-event particle identification. A TPC-type detector with GEM amplification and with multi-hit single-strip readout is proposed to be used as a tracking detector. The main challenges for such a detector are position resolution below 1 mm, high dynamic range (1000) and high-efficiency tracking up to 10 MHz ion rate. One of the planned improvements towards a high-rate capability of single-ion tracking is the multi-hit readout of the TPC detectors. Present TPC detectors with delay-line readout were tested with multihit electronics at the GSI fragment separator FRS with Au beam at 1 GeV/nucl. up to 150 kHz. Results are presented in comparison to single-hit readout.