Performance of TPC crosstalk correction

The performance of the CERN-Dubna-Milano (CDM) algorithm for TPC crosstalk correction is presented. The algorithm is designed to correct for uni-directional and bi-directional crosstalk, but not for self-crosstalk. It reduces at the 10% level the number of clusters, and the number of pads with a signal above threshold. Despite of dramatic effects in selected channels with complicated crosstalk patterns, the average longitudinal signal shape of a hit, and the average transverse signal shape of a cluster, are little affected by uni-directional and bi-directional crosstalk. The longitudinal signal shape of hits is understood in terms of preamplifier response, longitudinal diffusion, track inclination, and self-crosstalk. The transverse signal shape of clusters is understood in terms of the TPC's pad response function. The CDM crosstalk correction leads to an average charge decrease at the level of 15%, though with significant differences between TPC sectors. On the whole, crosstalk constitutes a relatively benign malfunction of the TPC readout which, after correction by the CDM algorithm and with proper attention to self-crosstalk, is not an obstacle to progress with physics analysis.