Spatial resolution improvement of PICOSEC Micromegas precise timing detectors

The combination of a Cherenkov radiator with a semi transparent photocathode and a Micromegas based amplification stage allows PICOSEC Micromegas detectors to achieve a time resolution of better than 15 ps. While tileable prototypes with 10×10 channels feature 1 × 1 cm 2 readout pads, finer readout granularity can be used to improve the spatial resolution. We report on the study of high readout granularity PICOSEC Micromegas prototypes which achieve around 0.5 mm spatial resolution with 3.5 mm large pads. No significant improvement was found when readout pad size was further reduced to 2.2 mm. The timing resolution of the leading pad was found to be slightly degraded but remained better than 20 ps for a medium granularity prototype. The achieved spatial resolution can enable PICOSEC Micromegas to be used as precise timing and moderate resolution tracking detector simultaneously.