Development of Muon Drift-Tube Detectors for High-Luminosity Upgrades of the Large Hadron Collider

TL;DR

This paper reports on the design, construction, and testing of advanced muon drift-tube detectors with 15 mm diameter tubes, optimized for high-luminosity LHC upgrades to handle increased background radiation while maintaining high spatial resolution.

Contribution

It introduces a new muon drift-tube detector design with improved rate capability and spatial resolution suitable for high-luminosity collider environments.

Findings

Detectors operate efficiently at high background rates.

Spatial resolution of 50 microns achieved at high rates.

Sense wire positioning accuracy is critical for performance.

Abstract

The muon detectors of the experiments at the Large Hadron Collider (LHC) have to cope with unprecedentedly high neutron and gamma ray background rates. In the forward regions of the muon spectrometer of the ATLAS detector, for instance, counting rates of 1.7 kHz/square cm are reached at the LHC design luminosity. For high-luminosity upgrades of the LHC, up to 10 times higher background rates are expected which require replacement of the muon chambers in the critical detector regions. Tests at the CERN Gamma Irradiation Facility showed that drift-tube detectors with 15 mm diameter aluminum tubes operated with Ar:CO2 (93:7) gas at 3 bar and a maximum drift time of about 200 ns provide efficient and high-resolution muon tracking up to the highest expected rates. For 15 mm tube diameter, space charge effects deteriorating the spatial resolution at high rates are strongly suppressed. The sense wires have to be positioned in the chamber with an accuracy of better than 50 ?micons in order to achieve the desired spatial resolution of a chamber of 50 ?microns up to the highest rates. We report about the design, construction and test of prototype detectors which fulfill these requirements.