Photocathode characterisation for robust PICOSEC Micromegas precise-timing detectors

TL;DR

This paper explores the development of robust photocathodes for PICOSEC Micromegas detectors, achieving sub-40 ps timing resolution and aiming for large-area, high-precision timing systems in high energy physics.

Contribution

It introduces the use of carbon-based photocathodes like DLC and B4C to improve robustness while maintaining excellent timing resolution.

Findings

DLC photocathodes achieved ~32 ps resolution

B4C photocathodes achieved ~34.5 ps resolution

Enhanced robustness supports large-area detector deployment

Abstract

The PICOSEC Micromegas detector is a~precise-timing gaseous detector based on a~Cherenkov radiator coupled with a~semi-transparent photocathode and a~Micromegas amplifying structure, targeting a~time resolution of tens of picoseconds for minimum ionising particles. Initial single-pad prototypes have demonstrated a~time resolution below 25 ps, prompting ongoing developments to adapt the concept for High Energy Physics applications, where sub-nanosecond precision is essential for event separation, improved track reconstruction and particle identification. The achieved performance is being transferred to robust multi-channel detector modules suitable for large-area detection systems requiring excellent timing precision. To enhance the robustness and stability of the PICOSEC Micromegas detector, research on robust carbon-based photocathodes, including Diamond-Like Carbon (DLC) and Boron Carbide (B4C), is pursued. Results from prototypes equipped with DLC and B4C photocathodes exhibited a~time resolution of approximately 32 ps and 34.5 ps, respectively. Efforts dedicated to improve detector robustness and stability enhance the feasibility of the PICOSEC Micromegas concept for large experiments, ensuring sustained performance while maintaining excellent timing precision.