Precise charged particle timing with robust PICOSEC Micromegas detectors

Le résumé fourni par la source

Future high-luminosity experiments require timing precision of the order of tens of picoseconds for pileup mitigation while aiming at instrumenting large active areas. PICOSEC Micromegas detectors combine a Cherenkov radiator with a photocathode and a two-stage gaseous amplification structure to achieve timing precision of $\lt25 \mathrm{ps}$ for minimum ionising particles [1] while allowing for economic area coverage. We present the development of tileable detector modules achieving high timing precision and optimisations in detector construction and signal routing which improve the achievable resolution to better than 20 ps. In parallel, new developments towards maintaining performance in challenging environments are pursued including alternative photoconversion layers which tolerate higher levels of ion back flow and resistive amplification structures. Carbon-based photocathodes including diamond-like carbon and $B_{4} C$ are evaluated and timing resolution values in the range of $30-40$ ps were obtained. Resistive detector technologies including resistive Micromegas and $\mu$ RWELL detectors were implemented to withstand high-rate environments. To profit from efficient protection against discharges and minimise the influence of delayed signal components on timing performance, high resistivity electrodes are used and comparable time resolution to non-resistive prototypes is demonstrated. The performance of different scalable readout approaches is compared to demonstrate the availability of suitable electronic readout schemes for multi-module detector systems. Dedicated preamplifiers coupled with waveform-digitising TDCs are used for constantfraction discrimination while a threshold-based timing ASIC is shown to allow for timewalk correction with complementary energy information. The presented developments illustrate the versatility of PICOSEC Micromegas precise timing detectors and their compatibility with challenging environments for high-pileup environments as well as photo detection.

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