Charged particle timing at sub-25 picosecond precision: The PICOSEC detection concept

Abstract

The PICOSEC detection concept consists in a "two-stage" Micromegas detector coupled to a Cherenkov radiator and equipped with a photocathode. A proof of concept has already been tested: a single-photoelectron response of 76 ps has been measured with a femtosecond UV laser at CEA/IRAMIS, while a time resolution of 24 ps with a mean yield of 10.4 photoelectrons has been measured for 150 GeV muons at the CERN SPS H4 secondary line. This work will present the main results of this prototype and the performance of the different detector configurations tested in 2016-18 beam campaigns: readouts (bulk, resistive, multipad) and photocathodes (metallic+CsI, pure metallic, diamond). Finally, the prospects for building a demonstrator based on PICOSEC detection concept for future experiments will be discussed. In particular, the scaling strategies for a large area coverage with a multichannel readout plane, the R&D on solid converters for building a robust photocathode and the different resistive configurations for a robust readout.

Quantum Systems for Enhanced High Energy Particle Physics Detectors

“…MicroPattern Gaseous Detectors (MPGDs) feature good granularity and are employed as tracking detectors as well as for the readout of Time Projection Chambers (TPCs) among other applications. State-of-the-art MPGDs achieve high spatial resolution, energy resolution and specific developments of precise timing MPGDs have demonstrated < 25 ps timing resolution [59].…”

“…A key application for photocathodes in gaseous radiation detectors is their use in precise timing detectors where primary charge production needs to occur at a specific time in a well defined location. By converting Cherenkov light from a radiator to primary electrons with a semi-transparent CsI photocathode and using a Micromegas-based amplification stage, the PICOSEC Micromegas detectors have achieved < 25 ps timing precision [59]. The efficiency of the photocathode directly translates to achievable timing resolution and while metallic or other robust photocathodes would offer resistance against environmental effects and ageing during prolonged operation, their QE is typically too low to be suitable for this detection concept.…”

Precise charged particle timing with the PICOSEC detector

“…There is a seminal paper by Sauli [1] that explicitly proves that proportional gaseous detectors, due to the statistics of the ionization can hardly exceed the ns-level for the time resolution per particle (∼ 6 ns for typical chamber dimensions). Recently, the RD-51 PICOSEC collaboration developed a detection technique [2] and published work [3,4] demonstrating that a special MicroMegas detector can reach a timing resolution better than 25 ps. In this detector (hereafter PICOSEC-MM) the drift region has been reduced to less than 200 μm in order to practically minimize the possibility of ionisation in the drift region, whilst the anode region remains at the typical size of MM (128 μm).…”