CERN Accelerating science

Thesis
Title	Entwicklung, Bau und Alterungsstudien von Straw Tube Driftkammern für das Äußere Spurkammersystem von LHCb
Translation of title	Development, construction and ageing studies of straw tube drift chambers for the outer tracker of LHCb
Author(s)	Walter, Michael (Heidelberg U.)
Publication	Heidelberg : Heidelberg U., 2004 - 185.
Thesis note	Thesis : Heidelberg : 2004
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; LHCb
Abstract	The Institute of Physics in Heidelberg participates in the development and construction of the Outer Tracker (OT) of LHCb at CERN. The OT is a modular system of straw tube drift chambers of up to 5 m length. This thesis reports the prototyping at the end of 2001 and the developments up to the definite design at the beginning of the mass production in spring 2004 at Heidelberg. Based on the experience gained from the prototype production and following operation tests, several components of the chamber, as well as the production process were gradually optimized. In addition to the operation tests of a full size prototype, ageing studies were performed with specially designed chambers at the X-ray facility of the Institute of Physics. Two drift gases Ar/CO2/CF4 and Ar/CO2 were tested to compare their ageing properties. Moreover the impact of the water content in the gases on wire etching and deposits on the anode wires was studied. In addition the possible impact of different construction materials on ageing was studied. As a result of this studies, it was found that uncontrollable effects occured independent of the water content with the drift gas Ar/CO2/CF4, which was the baseline solution, and some wires were damaged or even destroyed. In contrast, with dry Ar/CO2 no ageing effects were observed, which affects the operation of the straw tube drift chambers. This gas will therefore be used as drift gas for the Outer Tracker of LHCb.

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