Introduction to the particle detector world

• Jeremie Merlin

In this chapter, we will introduce the theoretical concepts of the particle detection and how we can highlighting new physics phenomenon by using powerful detectors to identify infinitesimal objects and their properties.

MPGD (Micro-pattern Gas Dectector) technology

• Jeremie Merlin

Gaseous detectors are by definition very light devices that can give a very high level of flexibility in term of geometry, composition and thus performance. For this reason, gaseous detectors are used in many HEP experiments with custom made designs and specific operating conditions. The Micro-Pattern Gaseous Detectors (MPGD), in particular, were developed in the continuity of the past gaseous technologies. They represent the latest generation of gaseous detectors, already used in several HEP experiments.

Introduction to the GEM detector

• Jeremie Merlin

The GEM technology was introduced by F. Sauli in 1996 to pre-amplify signals in MSGCs. The most used GEM-based detector consists of a triple-GEM structure. It has became one of the most popular MPGD technologies among several world-wide experiments, and it is also the starting point of newer detection structures for future HEP and medical applications.

Discussion : CMS muon spectrometer - RPC, Drift Tube, CSC, GEM Since the reconstruction of muons is a powerful tool to identify interesting decay modes, the muon spectrometer is one of the major assets of the CMS experiment. It is placed outside of the calorimeters and the magnet, embedded in the iron yokes. the CMS design includes three different technologies of gaseous detectors: the Drift Tubes (DT), the Cathode Strip Chambers (CSC) and the Resistive Plate Chambers (RPC) for a redundant and complementary trigger.

Discussion : Principles of the CMS GEM detector & its characteristics The aim of the CMS GEM Collaboration is the development and the installation of triple-GEM detectors in the forward region of the CMS muon end-caps. The collaboration has worked on the design and the development of the GEM based detectors in the context of the CMS requirements and constraints.

Discussion : status of LHC and CMS upgrade plan In order to increase its discovery potential, the LHC needs to be upgraded gradually, both the accelerator systems and the experiments. We can distinguish two major aspects of the upgrade: the increase of the center-of-mass energy in order to provide more energy during the collisions and reveal massive particles; the increase of the instantaneous luminosity to access very rare physics phenomena.

Discussion : GE11 production, installation and operation & ME0 project: Future GEM detector installation plan

GEM Discharge

• Jeremie Merlin

Electrical discharges is one of the main limitations of modern MPGD. Because of the microscopic nature of the GEM geometry, the presence of dust, contaminants or even the space charge context could lead to a local breakdown of the gas and sudden discharges. Such events can permanently damage the detector or the electronics. The understanding of the discharge phenomenon and the search for mitigation strategies is a critical part of the GEM detector development.

Discussion : Long-term operation and Aging processes Several mechanisms can affect the long-term operation of particle detectors and lead to a gradual and permanent degradation of the detection performance. The mechanical deformations of the structure of the detector can induce gain fluctuations of the order of several per cents over the surface of the detector, resulting in drastic non-uniformity of the performance. Moreover, the physical and electrical properties of some materials may change after several years causing bad electrical contacts, gas leaks, oxidation ... These effects are multiple and can be avoided most of the time with an appropriate choice of materials, operating conditions and the validation of the detectors with a strict quality control.

GEM Crosstalk

• Jeremie Merlin

The sharing of the readout signals over several readout strip is a key parameter for the proper reconstruction of physics events in the detector. However, in some cases, signals can be wrongly propagating to multiple readout sectors because of a parasitic effect called crosstalk. The understanding and the mitigation of the crosstalk issue is particularly important to prevent the generation of corrupted events and fake measurements.

Discussion : The future of MPGDs in HEP

Discussion : LHC schedule and Future detector upgrade plan

Discussion : School summary & Conclusion