Investigation of crosstalk effects in RD53A modules with 100 and 150 $\mathrm{\mu m}$ thick n-in-p planar sensors

The CMS and ATLAS detectors will face challenging conditions after the upgrade of the LHC to the High Luminosity LHC. In particular, the granularity of the pixel detectors should increase to mitigate the effect of pileup. Two possible sensor geometries are being investigated, $50\times50\ \mu m^2$ and $25\times100\ \mu m^2$, to handle these conditions. One of the main factors in choosing the pixel geometry is inter-channel charge induction or crosstalk, defined as the ratio of charge induced into neighboring pixels relative to the total charge. This charge induction will affect the data rates, position resolution, and track reconstruction efficiencies. Therefore, it should be investigated carefully. The effect of crosstalk is expected to depend on the chosen pixel geometry, threshold of the signal, and readout front-end. The readout chip in this study is RD53A, developed by the RD53 Collaboration, which is a prototype investigated by both the CMS and ATLAS collaborations implementing three different analog front-end designs. Crosstalk effects are larger for the $25\times100\ \mu m^2$ geometry, given the larger sensor capacitance. Both have been studied in the lab through direct charge injection, and also at DESY test beam facility by charge deposition of 5.6 GeV electrons in 150 $\mu m$ thick silicon pixels. The effects on the cross-talk due to varying the front-end, threshold, and the impinging position of the electrons will be presented.