{"id":{"repo_id":"freiburg-diss","oai_identifier":"oai:freidok.uni-freiburg.de:1314"},"canonical_url":"https://search.dev.ndltd.org/etd/freiburg-diss/oai:freidok.uni-freiburg.de:1314","repository":{"repo_id":"freiburg-diss","name":"University of Freiburg","base_url":"https://freidok.uni-freiburg.de/oai/oai2.php"},"display":{"title":"High rate and ageing studies for the drift tubes of the Atlas Muon Spectrometer","abstract":"The muon spectrometer of Atlas, one of the 4 experiments currently under construction at the Large Hadron Collider LHC, relies on Monitored Drift Tubes (MDTs) for track reconstruction in most of its regions. The MDTs will have to sustain count rates up to 1500 Hz/cm and must be able to survive an accumulated charge of up to 0.6 C/cm during 10 years of operation. This thesis presents results of high rate and ageing studies conducted at the CERN Gamma Irradiation Facility GIF; a series production Atlas muon chamber and a prototype of the gas recirculation system planned at LHC were used for the first time. <br>Test beam muons were utilized to evaluate the MDT high rate behaviour; questions of resolution, efficiency and changes in the drift properties of the operating gas were addressed. The measurements were complemented by simulations with the program GARFIELD. <br>For the ageing study the MDTs were irradiated over a period of several months, in which their performance was monitored weekly with cosmic muons. A loss in pulse height was observed for MDTs under gas recirculation after an accumulated charge equivalent to only 1 year of LHC operation, while tubes operated without gas recirculation did not show any evidence of ageing. Extensive material analyses were performed in order to determine the origin of the performance degradation.","abstract_html":"The muon spectrometer of Atlas, one of the 4 experiments currently under construction at the Large Hadron Collider LHC, relies on Monitored Drift Tubes (MDTs) for track reconstruction in most of its regions. The MDTs will have to sustain count rates up to 1500 Hz/cm and must be able to survive an accumulated charge of up to 0.6 C/cm during 10 years of operation. This thesis presents results of high rate and ageing studies conducted at the CERN Gamma Irradiation Facility GIF; a series production Atlas muon chamber and a prototype of the gas recirculation system planned at LHC were used for the first time. &lt;br&gt;Test beam muons were utilized to evaluate the MDT high rate behaviour; questions of resolution, efficiency and changes in the drift properties of the operating gas were addressed. The measurements were complemented by simulations with the program GARFIELD. &lt;br&gt;For the ageing study the MDTs were irradiated over a period of several months, in which their performance was monitored weekly with cosmic muons. A loss in pulse height was observed for MDTs under gas recirculation after an accumulated charge equivalent to only 1 year of LHC operation, while tubes operated without gas recirculation did not show any evidence of ageing. Extensive material analyses were performed in order to determine the origin of the performance degradation.","abstract_has_math":false,"creators":["Zimmermann, Stephanie"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Herten, Gregor"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T02:22:10Z","subjects":["Hochratenverhalten","Ortsauflösung","Effizienz","Drifteigenschaften","zirkulierendes Gassystem","Monitored Drift Tubes","ageing","high rate behaviour","gas recirculation"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://freidok.uni-freiburg.de/data/1314","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Herten, Gregor"]},{"key":"dc:creator","label":"Author","values":["Zimmermann, Stephanie"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["DoctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Hochratenverhalten","Ortsauflösung","Effizienz","Drifteigenschaften","zirkulierendes Gassystem","Monitored Drift Tubes","ageing","high rate behaviour","gas recirculation"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The muon spectrometer of Atlas, one of the 4 experiments currently under construction at the Large Hadron Collider LHC, relies on Monitored Drift Tubes (MDTs) for track reconstruction in most of its regions. The MDTs will have to sustain count rates up to 1500 Hz/cm and must be able to survive an accumulated charge of up to 0.6 C/cm during 10 years of operation. This thesis presents results of high rate and ageing studies conducted at the CERN Gamma Irradiation Facility GIF; a series production Atlas muon chamber and a prototype of the gas recirculation system planned at LHC were used for the first time. <br>Test beam muons were utilized to evaluate the MDT high rate behaviour; questions of resolution, efficiency and changes in the drift properties of the operating gas were addressed. The measurements were complemented by simulations with the program GARFIELD. <br>For the ageing study the MDTs were irradiated over a period of several months, in which their performance was monitored weekly with cosmic muons. A loss in pulse height was observed for MDTs under gas recirculation after an accumulated charge equivalent to only 1 year of LHC operation, while tubes operated without gas recirculation did not show any evidence of ageing. Extensive material analyses were performed in order to determine the origin of the performance degradation.","Diese Arbeit beschreibt Untersuchungen zum Hochraten- und Alterungsverhalten der Driftrohre (Monitored Drift Tubes, MDTs) des Atlas-Myonspektrometers. Am Large Hadron Collider LHC sind die Atlas-MDTs Zählraten von bis zu 1500 Hz/cm ausgesetzt; dies entspricht einer akkumulierten Ladung von 0.6 C/cm in 10 Betriebsjahren. Die hier vorgestellten Messungen wurden an der Gamma Irradiation Facility GIF am CERN durchgeführt. Dabei wurde eine Atlas-Myonkammer der Serienproduktion und ein Prototyp des am LHC vorgesehenen zirkulierenden Gassystems verwendet. <br>Das Hochratenverhalten der Driftrohre wurde mittels vom CERN SPS Beschleunigerkomplex erzeugten 100 GeV Myonen untersucht. Der Schwerpunkt lag hierbei auf den Größen Ortsauflösung, Effizienz und Änderungen im Driftverhalten des Betriebsgases. Die Messungen wurden ergänzt durch Simulationen mit dem Programm GARFIELD. <br>Während der Alterungsstudien wurden die MDTs über einen Zeitraum von mehreren Monaten intensiver Gamma-Strahlung ausgesetzt; ihr Verhalten wurde dabei wöchentlich in speziellen Referenz-Messungen mit kosmischen Myonen überwacht. Für mit Gaszirkulation betriebene Driftrohre wurde eine Reduktion der Pulshöhe ab einer akkumulierten Ladung, die äquivalent zu nur einem Jahr LHC Betrieb ist, beobachtet. Im Gegensatz dazu zeigten ohne Gaszirkulation betriebene Rohre keinerlei Alterungserscheinungen. Verschiedene chemische und oberflächenanalytische Verfahren ermöglichten es, den Ursprung der beobachteten Verschlechterung im MDT-Verhalten aufzuklären; den entsprechenden Methoden ist daher ein eigenes Kapitel der vorliegenden Arbeit gewidmet."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["High rate and ageing studies for the drift tubes of the Atlas Muon Spectrometer","Studien zum Hochraten- und Alterungsverhalten von Driftrohren des Atlas-Myonspektrometers"]}]}],"canonical_facts":{"dc:contributor":["Herten, Gregor"],"dc:creator":["Zimmermann, Stephanie"],"dc:description.abstract":["The muon spectrometer of Atlas, one of the 4 experiments currently under construction at the Large Hadron Collider LHC, relies on Monitored Drift Tubes (MDTs) for track reconstruction in most of its regions. The MDTs will have to sustain count rates up to 1500 Hz/cm and must be able to survive an accumulated charge of up to 0.6 C/cm during 10 years of operation. This thesis presents results of high rate and ageing studies conducted at the CERN Gamma Irradiation Facility GIF; a series production Atlas muon chamber and a prototype of the gas recirculation system planned at LHC were used for the first time. <br>Test beam muons were utilized to evaluate the MDT high rate behaviour; questions of resolution, efficiency and changes in the drift properties of the operating gas were addressed. The measurements were complemented by simulations with the program GARFIELD. <br>For the ageing study the MDTs were irradiated over a period of several months, in which their performance was monitored weekly with cosmic muons. A loss in pulse height was observed for MDTs under gas recirculation after an accumulated charge equivalent to only 1 year of LHC operation, while tubes operated without gas recirculation did not show any evidence of ageing. Extensive material analyses were performed in order to determine the origin of the performance degradation.","Diese Arbeit beschreibt Untersuchungen zum Hochraten- und Alterungsverhalten der Driftrohre (Monitored Drift Tubes, MDTs) des Atlas-Myonspektrometers. Am Large Hadron Collider LHC sind die Atlas-MDTs Zählraten von bis zu 1500 Hz/cm ausgesetzt; dies entspricht einer akkumulierten Ladung von 0.6 C/cm in 10 Betriebsjahren. Die hier vorgestellten Messungen wurden an der Gamma Irradiation Facility GIF am CERN durchgeführt. Dabei wurde eine Atlas-Myonkammer der Serienproduktion und ein Prototyp des am LHC vorgesehenen zirkulierenden Gassystems verwendet. <br>Das Hochratenverhalten der Driftrohre wurde mittels vom CERN SPS Beschleunigerkomplex erzeugten 100 GeV Myonen untersucht. Der Schwerpunkt lag hierbei auf den Größen Ortsauflösung, Effizienz und Änderungen im Driftverhalten des Betriebsgases. Die Messungen wurden ergänzt durch Simulationen mit dem Programm GARFIELD. <br>Während der Alterungsstudien wurden die MDTs über einen Zeitraum von mehreren Monaten intensiver Gamma-Strahlung ausgesetzt; ihr Verhalten wurde dabei wöchentlich in speziellen Referenz-Messungen mit kosmischen Myonen überwacht. Für mit Gaszirkulation betriebene Driftrohre wurde eine Reduktion der Pulshöhe ab einer akkumulierten Ladung, die äquivalent zu nur einem Jahr LHC Betrieb ist, beobachtet. Im Gegensatz dazu zeigten ohne Gaszirkulation betriebene Rohre keinerlei Alterungserscheinungen. Verschiedene chemische und oberflächenanalytische Verfahren ermöglichten es, den Ursprung der beobachteten Verschlechterung im MDT-Verhalten aufzuklären; den entsprechenden Methoden ist daher ein eigenes Kapitel der vorliegenden Arbeit gewidmet."],"dc:format.medium":["application/pdf"],"dc:subject":["Hochratenverhalten","Ortsauflösung","Effizienz","Drifteigenschaften","zirkulierendes Gassystem","Monitored Drift Tubes","ageing","high rate behaviour","gas recirculation"],"dc:title":["High rate and ageing studies for the drift tubes of the Atlas Muon Spectrometer","Studien zum Hochraten- und Alterungsverhalten von Driftrohren des Atlas-Myonspektrometers"],"dc:type":["DoctoralThesis"]},"updated_at":"2026-07-24T02:22:10Z"}