The ATLAS Muon Spectrometer upgrade for High-Luminosity LHC

Giorgia Proto

doi:10.1088/1742-6596/1690/1/012161

Abstract

The muon spectrometer of the ATLAS detector will undergo a major upgrade in order to cope with the operational conditions at the high-luminosity LHC. The trigger and readout system will need to support Level-0 trigger rates of 1 MHz and a latency of 10 μs. The readout electronics of all the trigger and precision chambers will be replaced and the precision chambers, currently not included in the hardware trigger, will be integrated into the Level-0 trigger in order to sharpen the momentum threshold and increase the system redundancy. New-generation RPC chambers will be installed in the inner barrel layer to increase the acceptance and robustness of the trigger. Some of the MDT chambers in the inner barrel layer will be replaced with new small-diameter MDTs. New TGC triplet chambers will replace the current TGC doublets in the barrel-endcap transition region to enhance the suppression of fake triggers in this region. A major upgrade of the power system is also planned. In this presentation the main detector technology developments of the project will be presented.

Highlights

In sight of HL-LHC program, the ATLAS Muon Spectrometer must be able to operate at instantaneous luminosity L of 7.5 × 1034 cm-2s-1 and at pileup of 200 maintaining its performance
The NSW is composed by MicroMegas (MM) and small-strip TGC chambers(sTGC), which will replace the Cathode Strip Chambers(CSC) and the MDT chambers of the innermost endcap wheels
Monitored Drift Tubes(MDTs) and Resistive Plate Chambers(RPCs): in order to maintain a high trigger efficiency, triplets of new RPC chambers with increased rate capability will be installed on the inner (BI) MDT chambers of the barrel

Summary

General Muon Upgrade plans

Thin Gap Chambers(TGCs) : In order to obtain a uniform level of purity for triggered muons over all the regions covered by the endcap trigger, the current EIL4 TGC doublet chambers will be replaced by TGC triplets with finer readout granularity In this way a more robust 2/3 majority logic and smaller coincidence windows can be used, reducing the rate of random coincidences to a negligible level. The NSW is composed by MicroMegas (MM) and small-strip TGC chambers(sTGC), which will replace the Cathode Strip Chambers(CSC) and the MDT chambers of the innermost endcap wheels These detectors can provide the muon Level-1 trigger system with online track segments of good angular resolution, in order to confirm that muon tracks originate from the IP. MDT hits will be used in the first level trigger to refine candidates based on RPC, TGC and NSW data

With new trigger logics planes instead of also the trigger

Time resolution