The upgrade of the ALICE TPC with GEMs and continuous readout

Abstract

The upgrade of the ALICE TPC will allow the experiment to cope with the high interaction rates foreseen for the forthcoming Run 3 and Run 4 at the CERN LHC. In this article, we describe the design of new readout chambers and front-end electronics, which are driven by the goals of the experiment. Gas Electron Multiplier (GEM) detectors arranged in stacks containing four GEMs each, and continuous readout electronics based on the SAMPA chip, an ALICE development, are replacing the previous elements. The construction of these new elements, together with their associated quality control procedures, is explained in detail. Finally, the readout chamber and front-end electronics cards replacement, together with the commissioning of the detector prior to installation in the experimental cavern, are presented. After a nine-year period of R&D, construction, and assembly, the upgrade of the TPC was completed in 2020.

88 pages, 60 figures

References in corpus (3)

• Progress on large area GEMs (VCI 2010)
• Layout and Assembly Technique of the GEM Chambers for the Upgrade of the CMS First Muon Endcap Station
• Secondary discharge studies in single and multi GEM structures

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• Discharge mitigation methods in MPGD-based detectors
• Reduction of ion back flow using a quadruple GEM detector with various gas mixtures
• New (TH)GEM coating materials characterised using spectroscopy methods
• Evidence for polyimide redeposition and possible correlation with sparks in Gas Electron Multipliers working in CF${}_4$ mixtures
• Observation on the bias current variation of a single mask triple GEM chamber
• Comparative study on charging-up of single, double and triple Gas Electron Multipliers (GEM)
• Impact of trace amounts of water on the stability of Micro-Pattern Gaseous Detectors measured in Ar-CO${}_2$ (90-10)