Podcast appearances and mentions of ATLAS experiment

Sponsors:• ◦ Visit Buildertrend to get a 60-day money-back guarantee on your Buildertrend account!• ◦ Pella Windows & Doors• ◦ Sub-Zero Wolf Cove Showroom PhoenixConnect with David James:Create and Construct Scottsdale website https://www.candcscottsdale.com/Instagram  https://www.instagram.com/createandconstructscottsdale/LinkedIn Page https://www.linkedin.com/in/david-james-97443211/Facebook https://www.facebook.com/people/Create-Construct-Scottsdale/100063567521715/Connect with Brad Leavitt:Website | Instagram | Facebook | Houzz | Pinterest | YouTube

Jacques Swanepoel is CTO at Seal Storage Technology, cloud storage and blockchain experts with over 100 years of experience in enterprise data storage from Seagate, Oracle, Cisco, and more.  Why you should listen Seal provides sustainable, immutable, and affordable data storage. They are stewarding their clients into decentralized cloud storage, and making Web3 an accessible reality for enterprises, research institutes, NFT, and Web3 firms alike. Seal has decentralized cloud storage partnerships with the ATLAS Experiment at CERN, UC Berkeley, and the University of Utah.  Supporting links Seal Andy on Twitter  Brave New Coin on Twitter Brave New Coin If you enjoyed the show please subscribe to the Crypto Conversation and give us a 5-star rating and a positive review in whatever podcast app you are using.

Vor zehn Jahren wurde am CERN das Higgs-Boson experimentell nachgewiesen. DW-Reporterin Sushmitha Ramakrishnan war als Physikstudentin damals von der Entdeckung fasziniert und fragt nun: Welche Erkenntnisse sollen die neuen Experimente bringen?

Choreographer and dancer SU Wen-Chi was at CERN in 2016. Her time in the Laboratory marked a long-term engagement with physics, and it inspired the trilogy comprising Unconditional Love, Infinity Minus One and Anthropic Shadow. Joining in conversation is experimental physicist Támara Vázquez Schröder, who works at the ATLAS Experiment at the Large Hadron Collider.  In this conversation, they discuss the role of symmetries in fundamental physics and performance art, the process of creating new artworks by SU Wen-Chi after her residency at CERN, and how broken symmetries can explain the natural world.  The conversation is hosted by Ana Prendes, Content Producer at Arts at CERN. Arts at CERN is made by Reduced Listening. The producer for this episode is Rebecca Gaskell, and the executive producer is Jack Howson.

Do you know what a lepton is? A muon? A quark? A boson? Bob can't even grasp the Facebook terms of service, but he found a particle physicist who both understands the nature of matter and was willing to explain it to him. Or try, anyway. Joining Bob for the first of a two-part conversation is Steven Goldfarb, a physicist at the University of Melbourne working on the ATLAS Experiment at CERN — the European particle physics consortium that operates the world's biggest particle accelerator near Geneva, Switzerland. Get full access to Bully Pulpit at bullypulpit.substack.com/subscribe

This week's guest is Ben David-Purcell (he/him). Ben is a physics PhD candidate at Carleton University in Ottawa, Ontario, Canada. He works on the ATLAS Experiment, based in CERN, Switzerland. ATLAS is an international collaboration with about 5000 members worldwide (Woah!) He's here to talk about finding your voice in a large collaboration. You can find Ben on Twitter at @BenDavisPurcell. A full-text transcript of this episode is available via google doc. Join us each Saturday at 3 pm EDT/12 pm PDT for the YouTube live stream where we talk about maintaining mental health and balance in grad school. The podcast episodes are posted the Tuesday after the live stream! Want to be a guest or know somebody we should be talking to? Fill out our google form! Follow our host Aidan on Twitter: @Aidan_Mowat Check out the PhD Balance website for more info on Grad Chat!

Our guest today is Dr. Mario Lassnig, a software engineer working on the ATLAS Experiment at CERN! Melanie and Mark put on their physics hats as they learn all about what it takes to manage the petabytes of data involved in such a large research project. Dr. Mario Lassnig Dr. Mario Lassnig has been working as a Software Engineer at the European Organisation for Nuclear Research (CERN) since 2006. Within the ATLAS Experiment, he is responsible for all aspects of its large-scale distributed data, including management, storage, network, and access. He is also one of the principal developers of the Rucio system for scientific data management. In his previous life, he developed mobile navigation software for multi-modal transportation in Vienna at Seibersdorf Research, as well as cryptographic smart-card applications for access control at the University of Klagenfurt. He holds a Master’s degree in Computer Science from the University of Klagenfurt, and a doctoral degree in Computer Science from the University of Innsbruck. Cool things of the week The Machines Can Do the Work, a Story of Kubernetes Testing, CI, and Automating the Contributor Experience blog Google Cloud grants $9M in credits for the operation of the Kubernetes project blog Improving job searches for veterans with Google Cloud’s Talent Solution blog Unity For Beginners… From a Beginner blog GCP Podcast Episode 134: Connected Games with Unity and Google Cloud with Brett Bibby and Micah Baker podcast Neural Information Processing Systems Conference site Interview Rucio - Scientific Data Management site CERN site ATLAS site Google Cloud Storage site Google Compute Engine site G Suite site GKE On-Prem site Rucio on GitHub site University of Oslo site University of Innsbruck site Brookhaven National Laboratory site University of Texas at Arlington site Square Kilometer Array site DUNE site LIGO Lab site Scientific Computing with Google Cloud Platform: Experiences from the Trenches in Particle Physics and Earth Sciences video GCP Podcast Episode 122: Project Jupyter with Jessica Forde, Yuvi Panda and Chris Holdgraf podcast Rucio Workshop site ACM/IEEE Supercomputing 2018 site Question of the week I am not familiar with Docker or Kubernetes - where can I get started? Docker Docker’s official “Getting Started” guide Katacoda’s free, interactive Docker course Kubernetes You should totally read this comic and interactive tutorial Katacoda’s free, interactive Kubernetes course Where can you find us next? Melanie will be at Deep Learning Indaba. Mark will be at Tokyo NEXT. We’ll both be at Strange Loop.

In this episode, we discuss... Steven's introduction to nuclear through physical chemistry.   An explanation of CERN's mission and the Large Electron Positron Collider.   Antimatter and the Z Boson.   Why the effective mass of particles increase as you get closer to the speed of light.   The misconceptions of particle collisions and an explanation of their interactions.   The benefits of partnering with others in the industry.   Collecting data through Z factories and the families of particles and quark.   The Theory of Super-Symmetry and the Grand Unification Theory.   Why it's better to refer to dark matter as invisible matter and its interaction with light in space.   The ATLAS Experiment and photographing particle collisions.   How measuring the Higgs Boson can help give us a new window into physics.  

We check out Skepticism in Latvia with an interview with Austra Muizniece who talks about the Rigvir scam. We xalso get two shorter interviews from the Ratio Conference in Bulgaria: One with Prof. Chris French who talks about his latest research on sleep paralysis and exploding head syndrom, and one with Dr Steven Goldfarb at the ATLAS Experiment at CERN and his part in the discovery of the Higgs Boson.

Der Hörspiel- und Filmemacher Jan Peters war 2013 "artist in residence" am CERN, der europäischen Organisation für Kernforschung in Genf. Zum Zeitpunkt des Stipendiums ist am ATLAS- Experiment gerade eine mehrmonatige Betriebspause, die dazu genutzt wird, den Pixel-Detektor aus- und umzubauen. Jan Peters hat während seines Stipendiums das Team um den Pixel-Detektor beim Wiedereinbau begleitet und zugesehen (und manchmal sogar mit angefasst), wie mehr als 24.000 Datenkabel erneut verbunden, durchgemessen und getestet wurden. // Mit Michael Leyton / video sonic synthesizer VIDEOVOX gespielt von Pit Przygodda / mit Dank an Ariane Koek/Arts@CERN / © Jan Peters Filmproduktion 2014 / Bayerischer Rundfunk Hörspiel und Medienkunst 2014

We talk to James Beacham, particle physicist with the ATLAS Experiment at the Large Hadron Collider at CERN about what it’s like to hunt for strange new subatomic particles.

[mp4] In this episode, we talk with Dr. Quentin Buat of Simon Fraser University about the graviton and extra dimensions. Produced by Dr. Lawrence Lee Original music by Dr. Lawrence Lee Recorded in Geneva, Switzerland Support from the ATLAS Experiment at CERN.

Diese Arbeit pr"asentiert zwei Analysen des Zerfallskanals hwwlnln mit den Daten des ATLAS experiments am LHC. Die analysierten Daten wurden im Jahr 2011 bzw. 2012 bei einer Schwerpunktsenergie von $sqrt{s} = 7 TeV$ bzw. $8 TeV$ aufgezeichnet und es wurde eine integrierte Luminosit"at von $25,textrm{fb}^{-1}$ erreicht. Die beiden Analysen unterscheiden sich im analysierten Phasenraum, der von der Massen $m_{rm H}$ des Higgs boson Signals abh"angt. Die Analyse f"ur Massen $m_{rm H} < 200 GeV$ wurde "uber die letzten Jahre optimiert, um in der Lage zu sein, eine Pr"azisions Messung der Kopplungen einer Resonanz bei $m_{rm H} approx 125 GeV$ durchzuf"uhren. Dabei wird ein Likelihood Fit der transversalen Masse $mT = sqrt{ (E_{T}^{ell ell} + P_{T}^{nu nu})^2 - | vec{P_{T}^{ell ell}} + vec{P_{T}^{nu nu}|^2} }$ angewendet. Mit einer statistischen Signifikanz von $6.1 sigma$ konnte ein hwwlnln Signal bei einer Masse $m_{rm H} = 125.36 pm 0.41 GeV$ beobachtet werden. Die Messung der Signalst"arke, dem Verh"altniss von experimentell bestimmtem Produktionswirkungsquerschnitt mal Verzweigungsverh"altnis zur theoretischen Prognose, ergab folgenden Wert: begin{align*} mu &= 1.08,^{+0.16}_{+0.15} textrm{(stat.)} ,^{+0.16}_{-0.14} textrm{(syst.)}, end{align*} was im Einklang mit der Standard-Modell-Vorhersage steht. Die Skalierung der Kopplungen des Higgs bosons an Fermionen und Bosonen wurden bestimmt zu: begin{align*} kappa_{F} &= 0.92,^{+0.30}_{-0.23} kappa_{V} &= 1.04,^{+0.10}_{-0.11}. end{align*} Zur Suche nach schweren, Higgs boson artigen Teilchen wurde die Analyse des hwwlnln Zerfallskanals f"ur Massen $m_{rm H} > 200 GeV$ optimiert. Auch im hohen Massenbereich wird ein Likelihood Fit an der Verteilung der transversalen Masse mT durchgef"uhrt. Es wurden obere Grenzen auf Produktionswirkungsquerschnitt mal Verzweigungsverh"altnis f"ur drei Szenarien bestimmt: Standard-Model-Higgs-Boson im Massenbereich $200 leq m_{rm H} leq 1 TeV$, Higgs boson artige Resonanz mit einer Zerfallsbreite von $1 GeV$ im Massenbereich $200 leq m_{rm H} leq 2 TeV$ und das elektroschwache Singlet Szenario im Massenbereich $200 leq m_{rm H} leq 1 TeV$, bei dem die Zerfallsbreite zus"atzlich zur Masse variiert wird. Es konnte in keinem getesteten Szenario ein statistisch signifikanter Daten"uberschuss beobachtet werden und dar"uberhinaus konnte ein Standard Modell artiges Higgs Boson bis zu einer Masse von $m_{rm H} = 661 GeV$ ausgeschlossen werden.

Es werden drei Analysen vorgestellt, die nach elektroschwach produzierten supersymmetrischen Teilchen in Proton-Proton-Kollisionen suchen. Die Kollisionen wurden mit dem ATLAS-Experiment am Large Hadron Collider aufgenommen. Zwei Leptonen (Elektronen oder Myonen), Jets und fehlende transversale Energie werden im Endzustand erwartet. `Simplified Models' werden genauso wie das `phenomenological Minimal Supersymmetric Standard Model' (pMSSM) verwendet, um die Produktion und den Zerfall von Gaugino-Paaren, also Paaren aus Charginos und Neutralinos, zu untersuchen. Die erste Analyse wird mit ATLAS Daten, die einer integrierten Luminosität von 4.7 fb^-1 entsprechen und im Jahr 2011 bei einer Schwerpunktenergie von sqrt(s)=7 TeV aufgenommen wurden, durchgeführt. Die direkte Produktion von Sleptonen sowie drei weitere Szenarien, in denen Gaugino-Paare über zwischenzeitliche Sleptonen zerfallen, werden untersucht. Besonders hervorgehoben wird die Triggerstrategie. Da kein Überschuss an Ereignissen in den ATLAS Daten beobachtet wird, können beispielsweise die Massen linkshändiger Sleptonen im Bereich von 85 bis 195 GeV mit 95% Konfidenzniveau ausgeschlossen werden. Hierfür wird ein Simplified Model, das die direkte Produktion von Sleptonen annimmt, verwendet, und das Neutralino besitzt eine Masse von 20 GeV. In einer zweiten Analyse werden 20.3 fb^-1 ATLAS Daten benutzt, die im Jahr 2012 mit sqrt(s)= 8 TeV aufgenommen wurden. Sieben Signalregionen zielen auf supersymmetrische Zerfallsketten ab, in denen zwei Leptonen mit entgegengesetztem Ladungsvorzeichen im Endzustand erwartet werden. Der dominante Standardmodelluntergrund besteht, analog zu der Analyse der 2011er Daten, aus ttbar-, Z/gamma*+jets- und zwei-Boson-Prozessen. Zwei-Lepton-Trigger werden kombiniert um die Ereignisse auszuwählen. Die Ergebnisse entsprechen den Erwartungen des Standardmodells und werden im Rahmen des pMSSM interpretiert. Massen des chi_1^+- können zwischen 100 und 105 GeV, 120 und 135 GeV sowie zwischen 145 und 160 GeV mit 95% Konfidenzniveau für ein masseloses chi_1^0 ausgeschlossen werden. Das Simplified Model für den Prozess chi_1^+ chi_1^- -> W^+ chi_1^0 W^- chi_1^0 -> l^+ nu chi_1^0 l^- nu chi_1^0 wird dazu verwendet. Mit der Simulation der direkten Produktion von Sleptonen in einem weiteren Simplified Model können Sleptonmassen zwischen 90 und 325 GeV ausgeschlossen werden (m_chi_1^0< 30 GeV). Die dritte Analyse wird ebenfalls mit 2012er Daten durchgeführt. Es wird ein Szenario betrachtet, in dem ein Chargino-Neutralino-Paar über ein W- und ein Higgsboson in einen Endzustand mit zwei gleichnamig geladenen Leptonen, zwei Quarks und zwei leichtesten Neutralinos zerfällt. Der Hauptuntergrund beruht auf Leptonen, die nicht vom primären Zerfallsvertex stammen, und wird mit Hilfe von ATLAS Daten bestimmt. Der Beitrag durch Standardmodell-Prozesse mit zwei Bosonen wird z.B. durch Schnitte auf die invariante Masse der Zerfallsprodukte des Higgsbosons und auf die effektive Masse, das ist die skalare Summe der Transversalimpulse der Leptonen, Jets und der fehlenden Transversalenergie, unterdrückt. Die Ergebnisse dieser Analyse sind noch nicht veröffentlicht. Man erwartet, dass die drei Massenpunkte mit Neutralinomassen unter 10 GeV und Charginomassen unter 150 GeV mit 95% Konfidenzniveau ausgeschlossen werden können.

This paper presents a study of the performance of the muon reconstruction in the analysis of proton–proton collisions at s√=7 TeV at the LHC, recorded by the ATLAS detector in 2010. This performance is described in terms of reconstruction and isolation efficiencies and momentum resolutions for different classes of reconstructed muons. The results are obtained from an analysis of J/ψ meson and Z boson decays to dimuons, reconstructed from a data sample corresponding to an integrated luminosity of 40 pb−1. The measured performance is compared to Monte Carlo predictions and deviations from the predicted performance are discussed

Wed, 1 Jan 2014 12:00:00 +0100 https://epub.ub.uni-muenchen.de/24273/1/oa_24273.pdf Aielli, G.; Ahsan, M.; Ahmad, A.; Ahlen, S. P.; Agustoni, M.; Aguilar-Saavedra, J. A.; Agatonovic-Jovin, T.; Aefsky, S.; Adye, T.; Adomeit, Stefanie; Adelman, J.; Addy, T. N.; Adams, D. L.; Adamczyk, L.; Acharya, B. S.; Abulaiti, Y.; Abreu, H.; Abramowicz, H.; AbouZeid, O. S.; Abolins, M.; Abi, B.; Aben, R.; Abdinov, O.; Abdel Khalek, S.; Abdallah, J.; Abbott, B.; Abajyan, T.; Aad

Fri, 26 Jul 2013 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/15994/ https://edoc.ub.uni-muenchen.de/15994/1/Heller_Claudio.pdf Heller, Claudio

Abstract: The Standard Model of particle physics has been successfully tested experimentally for over 30 years with no discrepancies. Yet a key piece of the Standard Model, and one needed to provide mass to elementary particles, remained undetected. Experimental evidence from the ATLAS experiment at the CERN LHC for the production of a new neutral boson was presented. The production and decay of this particle is compatible with Standard Model Higgs boson. Additional measurements expected using the full 2012 data set were discussed. Presented October 12, 2012.

Mon, 26 Nov 2012 12:00:00 +0100 https://edoc.ub.uni-muenchen.de/15459/ https://edoc.ub.uni-muenchen.de/15459/1/Will_Jonas.pdf Will, Jonas Zacharias ddc:530, ddc:500

Events with three or more prompt leptons are rare at hadron colliders. At the LHC, where high interaction energies and rates create extremely busy final states, such multilepton events are well suited as a probe for new physics beyond the Standard Model (BSM). Mike Hance describes some recent analyses from ATLAS based on multilepton signatures. In particular, focusing on new model-independent limits for anomalous production of multilepton events that can be used to test a variety of BSM scenarios.

Simone Zimmermann ist Doktorandin beim ATLAS-Experiment, eines der großen Experimente am CERN. In diesem Vortrag gibt sie eine Kurzeinführung in die Teichnephysik, berichtet vom Forschen am CERN und erklärt, wie genau man das Higgs findet.

This thesis presents the first measurement of the $ww$ production cross section in proton-proton collisions at $sqrt{s} = 7 TeV$ using the complete data set of $4.7 ifb$ collected by the ATLAS detector at the LHC in the year 2011. Three di-leptonic decay channels of the $ww$ pairs are used for this analysis: decays into two electrons, two muons, and decays into one electron and one muon. For each channel, a region with a high fraction of $ww$ events is selected and contributions from background processes are estimated using Monte Carlo simulations and data-driven techniques. In total, 1524 $ww$ candidate events are selected, with an estimated background of mbox{$545 pm 52$ events}. The result of the measurement is: $$sigma (pp rightarrow ww) = 52.6 pm 2.1 text{(stat)} pm 4.5 text{(syst)} pm 2.1 text{(lumi)} pb$$ This is compatible with the Standard Model cross-section prediction at next-to-leading order of $sigma (pp rightarrow ww) = 47.0^{+2.0}_{-1.5}$ pb.

Both the ATLAS and CMS detectors have operated with high efficiency in the first two years of LHC operation and produced an impressive number of physics results. In this talk I will discuss some of the differences between the detectors and describe some unique features of the ATLAS detector and how these features have been exploited in our physics analyses. I will describe some selected recent results and conclude with an overview of the planned, near term ATLAS detector upgrades.

The experimental signature of two leptons with the same electric charge is a great way to search for new physics as the backgrounds from Standard Model processes are quite low and a large variety of new physics models can produce this signature, e.g models with extended Higgs sectors, Supersymmetry, additional quark generations, and many more. Beate Heinemann reviews the ATLAS analyses in this signature based on the 2011 LHC data.

Thomas LeCompte of Argonne National Lab was the physics coordinator for the ATLAS experiment at the Large Hadron Collider. He talks about the instrument and its future, as we await the December 13th announcement as to whether the LHC has found the Higgs particle

Presented by Prof. Geoff Taylor on 2nd December 2011The Large Hadron Collider is operating beautifully well. Data from the highest energy particle collisions produced in the laboratory is being amassed at rates never before achieved. The big experiments, including the ATLAS experiment, on which Australian scientists collaborate, are operating extraordinarily well considering their complexity. The level of sophistication of analyses achieved with such a short period of operation has surprised the scientific world. Searches for the Higgs boson, Supersymmetry and other exotic phenomena are well underway. This presentation will give the status of these searches in the LHC/ATLAS program.The new ARC Centre of Excellence for Particle Physics at the Terascale ("CoEPP") brings together Australian experimentalist and theorists from Melbourne, Adelaide, Sydney and Monash. It will provide the resources and the focus to fully participate in the LHC program. A description of the CoEPP and its key goals will be covered in the presentation.

Presented by Prof. Geoff Taylor on 2nd December 2011The Large Hadron Collider is operating beautifully well. Data from the highest energy particle collisions produced in the laboratory is being amassed at rates never before achieved. The big experiments, including the ATLAS experiment, on which Australian scientists collaborate, are operating extraordinarily well considering their complexity. The level of sophistication of analyses achieved with such a short period of operation has surprised the scientific world. Searches for the Higgs boson, Supersymmetry and other exotic phenomena are well underway. This presentation will give the status of these searches in the LHC/ATLAS program.The new ARC Centre of Excellence for Particle Physics at the Terascale ("CoEPP") brings together Australian experimentalist and theorists from Melbourne, Adelaide, Sydney and Monash. It will provide the resources and the focus to fully participate in the LHC program. A description of the CoEPP and its key goals will be covered in the presentation.

The first seminar in this Series took place on Thursday 18 November 2010 at the Lighthouse. The ATLAS Collaboration will conduct experiments at the very edge of science, using one of four detectors located on the Large Hadron Collider (LHC) at CERN. The Collaboration consists of over 3000 scientist working in over 174 research institutes and universities located in 38 countries around the globe. In such a complex and spatially extended network (what we would today call a complex adaptive system) how do the knowledge flows allow the creation of one of the most sophisticated technological objects ever built? Drawing on a conceptual framework, the Information-Space or I-Space, Max Boisot described and tried to make sense of the ATLAS collaboration’s culture. He explored the lessons that the management of globally distributed ‘big science’ projects such as the ATLAS collaboration hold for other complex adaptive systems such as cities.

Alan Alda moderates as leading physicists Lisa Randall (Harvard) and Michael Tuts (Columbia), join CERN's Emma Sanders to explain new science coming from the Large Hadron Collider in Geneva, Switzerland. In particular, they share details of the ATLAS Experiment.

Alan Alda moderates as leading physicists Lisa Randall (Harvard) and Michael Tuts (Columbia), join CERN's Emma Sanders to explain new science coming from the Large Hadron Collider in Geneva, Switzerland. In particular, they share details of the ATLAS Experiment.

The Large Hadron Collider, starting in 2008, will be a "top factory" as top-antitop pairs will be produced with a cross section of about 830 pb at an instantaneous luminosity of 10^33 cm^-2 s^-1 during the first year. With about 30% probability top pairs decay semileptonically into a final state with four jets, lepton (electron or muon) and respective neutrino. For another 5% of the top pair events a dileptonic decay is expected. Here the final state signature is composed of two jets, two leptons and two neutrinos. In this thesis the precision for a top pair cross section measurement at the ATLAS experiment in the semileptonic and dileptonic channels with cut based analyses, applicable to the first data, was estimated. The analysis of the semileptonic decay focused especially on the study of background from QCD events either with leptons from semileptonic hadron decays or from hadrons falsely identified as electrons by the calorimeter. For the first 10 fb^-1 and assuming a fake electron probability of 10^-3 a precision for the cross section times the branching ratio of +- 0.5(stat) +- 30.4(syst) +- 24.0(lumi) pb has been estimated, corresponding to a relative precision of 16% for the theoretically predicted cross section times branching ratio of about 240 pb. The analysis in the dileptonic channel achieves a precision of +- 0.2(stat) +- 2.5(syst) +- 2.6(lumi) pb which translates into a relative error of 10% for the cross section times branching ratio of around 38 pb. The errors for both the semileptonic and the dileptonic channel are expected to improve as progress is made on the luminosity determination and the knowledge of the backgrounds from comparisons with measured data. A measurement of the cross-section ratio between the dileptonic and semileptonic channel is sensitive to scenarios of new phenomena with competitive top quark decay modes such as decays involving a charged Higgs boson. It has been estimated that such a ratio should be measurable with a relative precision of +- 0.7%(stat) +- 7.7%(sys) +- 3.1%(lumi) during the first year of ATLAS data-taking. Even though the systematic errors partially cancel in such a ratio the total uncertainty is still around 8% as the background estimates rely on theoretical predictions. This should also improve as soon as the models can be tested against measured data.

The LHC is a top quark factory producing ttbar events at a cross section of $833~mathrm{pb}$ in NLO. This corresponds to about $8cdot10^{6}$ ttbar events in the first nominal year of the LHC at the initial low integrated luminosity of $10~mathrm{fb^{-1}}$ being delivered. Approximately $44~%$ of the ttbar pairs decay hadronically into six jets. QCD multijet events with four to six final state partons are the main background to these ttbar events with a cross section many orders of magnitude above the ttbar multijet cross section. This study deals with the generation of fully hadronic ttbar events and QCD multijet events with up to six final state partons and their measurement in the ATLAS detector via fast parameterized simulation. The characteristics of the QCD events with respect to the ttbar signals are discussed and a cut-based selection for the separation of the ttbar events from the QCD background is introduced. The presented analysis is designed to use the physical and technical information available in the start-up period of the LHC. The extraction of the ttbar events results in more than 3000 remaining fully hadronic ttbar events which can be separated from the QCD multijet background in the first year of the LHC. This analysis also includes the reconstruction of the top-mass peak from fully hadronic ttbar events in the start-up period of the LHC and gives an estimate of the relative statistical uncertainty for the determination of the ttbar production cross section of approximately $4~%$ at an integrated luminosity of $10~mathrm{fb^{-1}}$.

The ATLAS detector, currently in its final installation phase at CERN, is designed to provide precise measurements of 14 TeV proton-proton collisions at the Large Hadron Collider. The measurements of the cross section and transverse momentum spectrum of the Z boson production at LHC provides first tests of the standard model in a new energy domain and may reveal exotic physics processes. Moreover, the properties of the Z boson resonance and its decay into two muons are known to very high precision from LEP experiments and hence can be used as a physics process for calibration and alignment. The Z boson production is also a common background process for many other physics analyses and must therefore be well understood. This thesis describes a measurement strategy of the cross section s for the process pp->Z->(mu)(mu) at the ATLAS experiment during its startup phase. As a result of this study a precision of d(sigma)/ (sigma) = 0.006(stat) + 0.008(sys) + 0.01 (pdf) is expected for an integrated luminosity of 50 pb^(-1), assuming a fully operational ATLAS detector, not including uncertainties in the luminosity measurements. A major goal of the approach presented was to minimize the dependence on Monte Carlo simulations. Hence, several methods for the determination of the detector response based on data have been studied. In addition, a strategy for the differential cross section measurement of the transverse momentum of the Z boson has been developed. In contrast to a measurement of the total cross section, it is expected that the statistical uncertainty dominates for the given integrated luminosity of 50 pb^(-1). The predicted high pT resolution of the ATLAS Inner Detector and the Muon Spectrometer allow for the first observation of interesting parton distribution effects, i.e. the so-called x-broadening, even with the limited statistics expected during the first data taking period.

Im Myonspektrometer des ATLAS-Detektors am LHC, bei dem Protonen mit einer Schwerpunktsenergie von 14~TeV kollidieren, werden Kammern aus Hochdruckdriftrohren zur Vermessung der Trajektorien der Myonen verwendet. Um den Impuls der Myonen aus der Krümmung ihrer Spur in dem 0.4~T starken Magnetfeld mit hinreichender Genauigkeit vermessen zu können, müssen zum einen die Driftrohre eine Ortsauflösung von $sigma_{r} leq 100; mu text{m}$ liefern und zum anderen muss die Position jedes Annodendrahtes, also auch die Geometrie jeder Kammer, mit einer Genauigkeit von deutlich besser als 100~$mu$m bekannt sein. Die Arbeit beschäftigt sich mit diesem Problem an zwei Fronten. Wegen der hohen Luminosität des Beschleunigers und des großen Wirkungsquerschnittes für Proton-Proton-Kollisionen, herrscht im Myonspektrometer ein erheblicher Untergrund an Photonen und Neutronen. Um das Verhalten der Driftrohre bei hoher Untergrundzählrate zu untersuchen, wurde eine Teststrahlmessung durchgeführt, bei der neben einem hochenergetischen Myonstrahl (100~GeV) auch eine 740~GBq starke $gamma$-Quelle die Kammer beleuchtete. Mittels eines hochauflösenden Referenzdetektors aus Silizium-Streifenzählern wurden Ortsauflösung und Effizienz bei unterschiedlichen Untergrundstrahlungsniveaus untersucht. Eine Möglichkeit die Ortsauflösung zu verbessern, in dem mittels einer in die Ausleseelektronik integrierten Pulshöhenmessung die Abhängigkeit zwischen Signalzeit und Pulshöhe betrachtet wird, wurde untersucht und weiterentwickelt. Damit konnte die Auflösung unabhängig von der Photonenbestrahlung um 13~$%$ verbessert und die angestrebte Ortsauflösung von 100~$mu$m selbst beim Dreifachen der erwarteten Untergrundstrahlung erreicht werden. In Zusammenarbeit mit dem Max-Plank-Institut für Physik in München und dem Joint Institute for Nuclear Research in Dubna werden 88 der 1226 Myonkammern gebaut. Zur ersten Inbetriebnahme und Überprüfung der Qualität dieser Kammern wurde der Höhenstrahlmessstand eingerichtet. Insbesondere kann dort die Geometrie einer Kammer bestimmt werden, in dem sie zwischen zwei Referenzkammern eingebaut wird, deren Geometrie mit einem Röntegentomographen genau vermessen wurde. Mit Hilfe dieser Kammern wird die Spur des kosmischen Myons bestimmt. Aus systematischen Abweichungen zwischen dieser Referenzspur und den Messungen in der zu testenden Kammer, kann die Position eines jeden Drahtes mit einer Genauigkeit in der Größenordnung 10~$mu$m bestimmt werden. Diesbezüglich wird die Arbeit von Oliver Kortner~cite{olivers_dis} fortgesetzt, also der Messstand hin zu drei vollständig ausgelesenen Kammern ausgebaut und seine Leistungsfähigkeit überprüft. Der Messstand erlaubt es, mechanische Ungenauigkeiten der Kammern, die allerdings nur selten vorkommen, zuverlässig zu finden und zu quantifizieren. Dadurch sind auch Kammern die von der Normgeometrie abweichen vollständig beim ATLAS-Experiment einsetzbar, wenn die im Messstand ermittelten Geometrieparameter in der Spurrekonstruktion berücksichtigt werden.