Studies of the Silicon Tracker resolution using data

Several parameters that influence the hit resolution of the Silicon Tracker have been determined from data. These include charge sharing, cross talk and Lorentz deflection. A charge sharing width of ~4 $\mu$m has been measured. No charge loss has been observed in the interstrip region. The cross talk to the neighbouring strips is found to vary between 4 − 14%, depending on the total capacitance (sensors plus cable), on whether it is the left or right neighbour and on the Beetle channel number (odd or even). The Lorentz deflection was also investigated and was observed to be small. Finally, the new parameters have been inserted in the LHCb Monte Carlo simulation to update the $\eta$-correction functions required for the reconstruction of tracks. Compared to the previous tuning the hit resolution in the simulation has increased from ~35 $\mu$m to ~50 $\mu$m.