Long-term geometry stability of ATLAS MDT chambers studied with a high-precision X-ray tomograph

The CERN X-ray tomograph measures the 2-dimensional position of MDT chamber wires with a total uncertainty of less than 5 microns. This dedicated facility has assured consistent production quality of chamber geometries over the five year construction phase between 2000 and 2005 by sampling about 15% of the total 1200 MDT chambers produced. Part of the tomograph measurement capacity has been used to perform re-measurements of selected chambers. We briefly describe the tomograph facility and its capabilities, present a global view of the mechanical accuracy and consistency of the full MDT production and then summarize the results obtained from the chamber re-measurements and discuss their possible implications for long-term MDT geometry stability.