Speaker
Description
Physics experiments use time to measure physical quantities or to apply selection conditions. The required precision is driven by each specific case. Tens of picoseconds for minimum ionizing particle is what the future physics at the HL-LHC is requiring in time precision for pile-up and background subtraction. In some circumstances, high precision timing has to coexist with high rates and high dose conditions. Assuming this context as one of the highest motivating force, numerous applications outside high-energy physics will profit form this precision. New developments and research in detector technologies and readout electronics are the key points.
Gaseous detectors are widely used in experiments because of their cost effective solution for large area coverage. Excellent properties have been achieved on large surfaces with the recent developments on Micro Pattern Gaseous Detectors (MPGD): gain, space and energy resolution, stability, radiation hardness, low material budget and operation in high rate environments. Time wise, few nanoseconds of time resolution are achievable with the existing MPGD detectors where ionization of the gas itself is the source of primary charge. Sub nanosecond resolution has been obtained in gaseous detectors using solid converter (primary ionization localized in time and space), but the results are still far from aimed time resolution of tens of picosecond.
Our detection concept to obtain this precision is a thin drift Micromegas coupled to a Cerenkov-radiator front window and a semi-transparent UV photocathode. A 1cm2 prototype has been built in order to prove the principle. Single-photoelectron response better than 100ps has been measured with a femtosecond UV laser at IRAMIS. Time resolution better than 50 ps, with a mean yield of about 10 photoelectrons, has been measured at the CERN SPS extraction lines with minimum ionizing particles. Results and potential improvements will be presented.
The excellent results achieved justify the need of addressing now numerous topics in view of the use of the Picosec detector in experiments: lifetime (of the photocathodes in particular), robustness (spark protection), scaling to multichannel readout, large area coverage, front end electronics, high rate and so on so forth. Preliminary results on ongoing developments (resistive micromegas, multi anode readout) will be presented. R&D on solid converter (photocathodes, secondary emitter) will represent clearly one of the most important subjects of our next R&D lines and it will necessarily involve various expertize from different fields. This item will be discussed going through the status of the project and the future research plans.
