Construction and test of high precision drift-tube (sMDT) chambers for the ATLAS muon spectrometer

TL;DR

This paper reports on the construction, assembly, and testing of high-precision sMDT drift-tube chambers for the ATLAS muon spectrometer upgrade, emphasizing their design, production process, and quality control.

Contribution

It introduces a new design of sMDT chambers with smaller drift-tubes, improved precision, and a semi-automated assembly process for the ATLAS upgrade.

Findings

Chambers achieve 10 μm wire positioning accuracy.

Assembly completed within one week using semi-automated production.

Chambers are compatible with existing ATLAS services and have redundant layers.

Abstract

For the upgrade of the ATLAS muon spectrometer in March 2014 new muon tracking chambers (sMDT) with drift-tubes of 15 mm diameter, half of the value of the standard ATLAS Monitored Drift-Tubes (MDT) chambers, and 10~$\mu$m positioning accuracy of the sense wires have been constructed. The new chambers are designed to be fully compatible with the present ATLAS services but, with respect to the previously installed ATLAS MDT chambers, they are assembled in a more compact geometry and they deploy two additional tube layers that provide redundant rack information. The chambers are composed of 8 layers of in total 624 aluminium drift-tubes. The assembly of a chamber is completed within a week. A semi-automatized production line is used for the assembly of the drift-tubes prior to the chamber assembly. The production procedures and the quality control tests of the single components and of the complete chambers will be discussed. The wire position in the completed chambers have been measured by using a coordinate measuring machine.