A Novel Diamond-like Carbon based photocathode for PICOSEC Micromegas detectors

TL;DR

This paper introduces a diamond-like carbon (DLC) photocathode for PICOSEC Micromegas detectors, demonstrating improved robustness and competitive timing resolution compared to traditional CsI photocathodes.

Contribution

The study presents the development and testing of DLC photocathodes, showing their resistance to ion bombardment and effective performance in muon detection.

Findings

DLC photocathodes have an optimal thickness of about 3 nm.

DLC exhibits better resistance to ion bombardment than CsI.

The PICOSEC detector with DLC achieved 42 ps time resolution and 97% efficiency.

Abstract

The PICOSEC Micromegas (MM) detector is a precise timing gaseous detector based on a MM detector operating in a two-stage amplification mode and a Cherenkov radiator. Prototypes equipped with cesium iodide (CsI) photocathodes have shown promising time resolutions as precise as 24 picoseconds (ps) for Minimum Ionizing Particles. However, due to the high hygroscopicity and susceptibility to ion bombardment of the CsI photocathodes, alternative photocathode materials are needed to improve the robustness of PICOSEC MM. Diamond-like Carbon (DLC) film have been introduced as a novel robust photocathode material, which have shown promising results. A batch of DLC photocathodes with different thicknesses were produced and evaluated using ultraviolet light. The quantum efficiency measurements indicate that the optimized thickness of the DLC photocathode is approximately 3 nm. Furthermore, DLC photocathodes show good resistance to ion bombardment in aging test compared to the CsI photocathode. Finally, a PICOSEC MM prototype equipped with DLC photocathodes was tested in muon beams. A time resolution of around 42 ps with a detection efficiency of 97% for 150 GeV/c muons were obtained. These results indicate the great potential of DLC as a photocathode for the PICOSEC MM detector.