Construction and Test of New Precision Drift-Tube Chambers for the ATLAS Muon Spectrometer

TL;DR

This paper discusses the development, construction, and testing of new small-diameter Muon Drift Tube (sMDT) chambers for the ATLAS muon spectrometer, enhancing rate capability and installation efficiency for high-luminosity LHC conditions.

Contribution

It introduces the design and mass production methods of sMDT chambers with high wire positioning accuracy, suitable for upgrade and replacement in the ATLAS detector.

Findings

Achieved 5 μm wire positioning accuracy in mass production.

Developed optimized assembly methods for large-size chambers.

Prepared for installation during the 2016/17 LHC shutdown.

Abstract

ATLAS muon detector upgrades aim for increased acceptance for muon triggering and precision tracking and for improved rate capability of the muon chambers in the high-background regions of the detector with increasing LHC luminosity. The small-diameter Muon Drift Tube (sMDT) chambers have been developed for these purposes. With half of the drift-tube diameter of the MDT chambers and otherwise unchanged operating parameters, sMDT chambers share the advantages of the MDTs, but have an order of magnitude higher rate capability and can be installed in detector regions where MDT chambers do not fit in. The chamber assembly methods have been optimized for mass production, minimizing construction time and personnel. Sense wire positioning accuracies of 5 ?micons have been achieved in serial production for large-size chambers comprising several hundred drift tubes. The construction of new sMDT chambers for installation in the 2016/17 winter shutdown of the LHC and the design of sMDT chambers in combination with new RPC trigger chambers for replacement of the inner layer of the barrel muon spectrometer are in progress.