Garchinger Maier-Leibnitz-Kolloquium: Precision Muon Tracking Using Large-Area Micropattern Gaseous Detectors at the Current Luminosity and Energy Frontier

Thursday 20 Apr 2023, 16:15 → 17:15 Europe/Berlin

Lecture Hall, ground floor (west) (LMU building Am Coulombwall 1, campus Garching)

Precision muon tracking and transverse momentum determination is an important tool in high energy physics experiments. The quasi background free detection of muons allows for the study of so called golden channels, e.g. H --> ZZ --> 4mu. Gaseous multi-wire chambers and drift-chambers played over decades the dominant role in large area muon spectrometers, culminating in the 1992 Nobel Price for Georges Charpak.
For recent and near future increase in luminosity as planned for the pp storage ring LHC at CERN from 2x10^34 /(cm^2sec) to 7.5x10^34 /(cm^2 sec), muon detectors square meter in size with finer granularity and short ion drift time are needed to maintain highest spatial resolution and high detection efficiency. 10 x 10 cm^2 Micropattern gaseous detectors with miniaturised readout geometries underwent an almost 2 decade long very successful development phase. From the beginning of their development they showed excellent spatial resolution and extreme hit rate capability. Among the multitude of devolpments only 2 types, resistive anode Micromegas and GEMs, show tolerance against highly ionising background. For all the other micropattern developments designed for minimum ionising muon detection the lifetime of the detectors was strongly reduced by tiny but often discharges induced by charge densities exceeding the Raether limit due to highly ionising background events. To prevent the destruction of the tiny microstructures by the energetic load of the discharges the resistive anode technology was the breakthrough for Micromegas (MICRO MEsh GAseous Structures). GEM detectors (Gaseous Electron Multiplier) are less sensitive to these effects, as gas amplification and microstructures are well separated. Both technologies have been chosen for upgrades of the forward muon spectrometers of the two major LHC detectors at CERN, Micromegas for the two new Small Wheels in ATLAS and GEMS for backup of three stations of the CSC (cathode strip chambers) detectors at CMS. The talk introduces GEMs and Micromegas and concentrates on the performance and the development of large-area detectors and demonstrates the transition from small area developments to large area applications.

Hybrid access via ZOOM:
https://lmu-munich.zoom.us/j/98457332925?pwd=TWc3V1JkSHpyOTBPQVlMelhuNnZ1dz09
Meeting ID: 984 5733 2925
Passcode: 979953

 

 

kolloquium-20-04-23.pdf