  In this work, a fast method of vertex reconstructing for incident ions in GEM
detectors was proposed. As inspired by the Time Projection Chamber (TPC), the
time information of the consecutive signal samples from Front End Electronics
(FEE) was employed. To demonstrate the method, an experiment involving a
2D-readout THGEM detector with an APV-25 FEE was taken. With one experiment
dependent parameter in the analysis, the proposed method led to a spatial
resolution of 0.45 mm, compared with the same number of 9.10 mm from the
traditional center of gravity method.
