engSchiavi, CCervetto, MParodi, FKostantinidis, NSutton, MBaines, J T MEmeliyanov, DDrevermann, HFast Tracking for the Second Level Trigger of the ATLAS Experiment Using Silicon Detectors DataDetectors and Experimental TechniquesATL-DAQ-CONF-2005-011ATL-COM-DAQ-2005-011Online track reconstruction is an important ingredient for event selection at Large Hadron Collider (LHC) experiments. In the ATLAS experiment the first stage where this goal will be achievable is the software-based Second Level Trigger (LVL2). In this contribution we present an algorithm for fast pattern recognition and reconstruction of charged tracks and of the primary vertex in the framework of the High Level Trigger (HLT) of ATLAS. The pattern recognition makes extensive use of Monte Carlo Look Up Tables to quickly identify, in the innermost layers of the ATLAS silicon detectors, triplets of space points reconstructed from hits produced by the same track. The reconstruction strategy is compared, in the ATLAS LVL2 framework, with an alternative tracking algorithm, showing the complementarity of the two approaches. The algorithm’s performance is presented for different event topologies and luminosities, showing good tracking capabilities and uniform results with mean execution times which are compatible with the LVL2 requirements.2005http://cds.cern.ch/record/830388DAQ and Triggerhttp://cds.cern.ch/record/830388oai:cds.cern.ch:830388 engMoraes, AButtar, CDawson, IPrediction for Minimum Bias and the Underlying Event at LHC Energies 010Detectors and Experimental TechniquesATL-PHYS-PUB-2005-007ATL-COM-PHYS-2005-010In this report we investigate the models employed by PYTHIA and PHOJET Monte Carlo event generators used to describe soft interactions in hadron-hadron collisions. The prime aim of this study is to predict minimum bias and underlying event levels of particle production and event activity for the LHC as accurately as these models allow us, thus providing indispensable information for simulations. Focusing on a wide range of measurements dominated by soft interactions in proton-proton and proton-anti-proton collisions, one of the aims of this study is to check the consistency of these models when compared to data and evaluate how efficient their descriptions of low-pT processes are. Based on comparisons to a wide range of minimum bias and underlying event data we present a tuning for PYTHIA6.214 and compare it to other PYTHIA tunings.2005http://cds.cern.ch/record/827339Physicshttp://cds.cern.ch/record/827339oai:cds.cern.ch:827339All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PUBNOTES/ATL-PHYS-PUB-2005-007 engNegri, AArmstrong, SDos Anjos, ABaines, J T MBee, C PBiglietti, MBogaerts, J A CBoisvert, VBosman, MCaron, BCasado, M PCataldi, GCavalli, DCervetto, MComune, GConde-Muíño, PDe Santo, ADíaz-Gómez, MDosil, MEllis, NickEmeliyanov, DEpp, BEtienne, FFalciano, SFarilla, AGeorge, SGheteo, VGonzález, SGrothe, MKabana, SKhomich, AKilvington, GKonstantinidis, N PKootz, ALowe, ALuminari, LMaeno, TMasik, JDi Mattia, AMeessen, CMello, A GMerino, GMoore, RMorettini, PNikitin, N VNisatip, APadillaf, CPanikashvili, NParodi, FPérez-Réale, VPinfold, J LPinto, PQian, ZResconi, SRosati, SSánchez, CSantamarina-Rios, CScannicchio, D ASchiavi, CSegura, EDe Seixas, J MSivoklokov, S YuSoluk, R AStefanidis, ESushkov, SSutton, MTapprogge, StefanThomas, ETouchard, FVenda-Pinto, BVercesi, VWerner, PWheeler, SWickens, F JWiedenmann, WWielers, MZobernig, GDesign, deployment and functional tests of the on-line Event Filter for the ATLAS experiment at LHCDetectors and Experimental TechniquesATL-DAQ-CONF-2005-004ATL-COM-DAQ-2005-008CERN-ATL-DAQ-CONF-2005-004The Event Filter selection stage is a fundamental component of the ATLAS Trigger and Data Acquisition architecture. Its primary function is the reduction of data flow and rate to values acceptable by the mass storage operations and by the subsequent off-line data reconstruction and analysis steps. The computing instrument of the EF is generally organized as a set of independent sub-farms, each connected to one output of the Event Builder switch fabric. Each sub-farm comprises a number of processors analyzing several complete events in parallel. This paper describes the design of the ATLAS EF system, its deployment in the 2004 ATLAS combined test beam together with some examples of integrating selection and monitoring algorithms. Since the processing algorithms are not specially designed for EF but are inherited as much as possible from the off-line ones, special emphasis is reserved to system reliability and data security, in particular for the case of failures in the processing algorithms. Another key design element has been system modularity and scalability. The EF shall be able to follow technology evolution and should allow for using additional processing resources possibly remotely located.2005http://cds.cern.ch/record/821930DAQ and Triggerhttp://cds.cern.ch/record/821930oai:cds.cern.ch:821930 engHassani, SSearch for the standard model $H \to ZZ^{*} \to 4\mu$ with full ATLAS detector simulationParticle Physics - PhenomenologyATL-COM-PHYS-2005-014The discovery potential of the ATLAS detector for the Standard Model Higgs decay to the four muon final state is investigated. All results muons and Higgs-boson mass reconstruction have been obtained from a full detector simulation using the most up to date detector l ayout. Muon isolation criteria are used to reject event with muons produced in heavy flavor decays, while variables based on the scalar and CP-even nature of the Higgs are used to improve the rejection of the irreducible background. A deterioration of the detector performance with respect to the Physics Technical Design Report(TDR) results is found. The use of multivariate techniques makes it possible to recover of the discovery potential reported in the ALTAS Physics TDR.2005-04-04http://cds.cern.ch/record/830649Physicshttp://cds.cern.ch/record/830649oai:cds.cern.ch:830649 engGagnon, PInvisible Higgs boson decays in the ZH and WH channelsDetectors and Experimental TechniquesATL-PHYS-PUB-2005-011ATL-COM-PHYS-2003-011This note provides details on the analysis developed to select invisible Higgs decays in the ZH and WH channels. The study was performed with Fortran-based ATLFAST and shows the feasibility of the ZH channel at 2.7 sigma level for 10 fb-1 of data. It also demonstrates why the WH channel is not usable due to the overwhelming W inclusive background.2003http://cds.cern.ch/record/681580Physicshttp://cds.cern.ch/record/681580oai:cds.cern.ch:681580All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PUBNOTES/ATL-PHYS-PUB-2005-011 engKonstantinidis, N PStefanidis, SSutton, M ROptimisation of the size of the EmTau Region of Interest for the ATLAS Level-2 Trigger using the Electromagnetic CalorimeterDetectors and Experimental TechniquesATL-DAQ-PUB-2005-002ATL-COM-DAQ-2005-038CERN-ATL-COM-DAQ-2005-038A study for optimizing the size of the EmTau Region of Interest (RoI) using the pointing information from the Electromagnetic Calorimeter is presented. The benefits from the reduced RoI size in terms of timing and performance for tracking using the IDSCAN package at the LVL2 Trigger are discussed in details.2005-10-28http://cds.cern.ch/record/899861DAQ and Triggerhttp://cds.cern.ch/record/899861oai:cds.cern.ch:899861 doi:10.5170/CERN-2005-011.269engSpiwoks, RalfDos Anjos, AEllis, NickHaller, JIqbal, NLandon, MWengler, TWiedenmann, WZobernig, HConfiguration of the ATLAS TriggerDetectors and Experimental TechniquesATL-DAQ-CONF-2005-031ATL-COM-DAQ-2005-034CERN-ATL-DAQ-CONF-2005-031The ATLAS detector at CERN's LHC will be exposed to proton-proton collisions at a rate of 40 MHz. In order to reduce the data rate, only potentially interesting events are selected by a three-level trigger system. Its first level is implemented in electronics and firmware, and aims at reducing the data rate to about 75 kHz. The second and third trigger levels are based on software and reduce the data rate to about 200 Hz. To prepare the full trigger chain for the online event selection according to a certain strategy, a system is being set up that provides the corresponding information to all parts of the trigger chain, e.g. values of hardware registers in the first-level trigger or steering parameters in the high-level trigger algorithms. The same information is used to configure offline trigger simulation and to run offline analysis. This article gives an overview of the system and its main components.CERN2005http://cds.cern.ch/record/88954810.5170/CERN-2005-011.269DAQ and Triggerhttp://cds.cern.ch/record/889548oai:cds.cern.ch:889548LECC 2005, Heidelberg, September 2005. doi:10.5170/CERN-2005-011.274engPauly, ThiloBorrego-Amaral, PAsk, SEllis, NickFarthouat, PGällnö, PHaller, JKrasznahorkay, AMaeno, TPessoa-Lima, HResurreccion-Arcas, ISchuler, GDe Seixas, J MSpiwoks, RTorga-Teixeira, RWengler, TATLAS Level-1 Trigger Timing-In StrategiesDetectors and Experimental TechniquesATL-DAQ-CONF-2005-035ATL-COM-DAQ-2005-036CERN-ATL-DAQ-CONF-2005-035The ATLAS detector at CERN's LHC will be exposed to proton-proton collisions at a bunch-crossing rate of 40 MHz. In order to reduce the data rate, a three-level trigger system selects potentially interesting events. Its first level is implemented in electronics and firmware, and aims at reducing the output rate to under 100 kHz. The Central Trigger Processor (CTP) combines information from the calorimeter and muon trigger processors, and makes the final Level-1 Accept (L1A) decision, which is transferred to all sub-detector front-ends. The functioning of the Level-1 Trigger is based on the correct timing of the signals. In this paper we present various strategies for sub-detector timing-in, in particular how to arrive at a decent initial timing setup using test-pulses in standalone mode, and in global mode with the CTP. In addition we describe how the beam pick-up detectors are a powerful tool to further refine the timing with bunches in the LHC machine. In this context we describe new developments on a proposal for precision read-out of the ATLAS beam pick-up detectors with commercial oscilloscopes in order to monitor the phase of the clock with respect to the LHC bunches.CERN2005http://cds.cern.ch/record/89824210.5170/CERN-2005-011.274DAQ and Triggerhttp://cds.cern.ch/record/898242oai:cds.cern.ch:898242 doi:10.1109/RTC.2005.1547532engSantamarina-Rios, CConde-Muíño, PDos Anjos, AArmstrong, SBaines, J T MBee, C PBiglietti, MBogaerts, J A CBosman, MCaron, BCasado, M PCataldi, GCavalli, DComune, GCrone, GDamazio, DDe Santo, ADíaz-Gómez, MDi Mattia, AEllis, NickEmeliyanov, DEpp, BFalciano, SGaritaonandia, HGeorge, SGesualdi-Mello, AGhete, VGoncalo, RHaller, JKabana, SKhomich, AKilvington, GKirkc, JKonstantinidis, N PKootz, ALankford, AJLowe, ALuminari, LMaeno, TMasik, JMeessen, CMoore, RMorettini, PNegri, ANikitin, NNisati, AOsuna, CPadilla, CPanikashvili, NParodi, FPasqualucci, EPérez-Réale, VPinfold, James LPinto, PQian, ZResconi, SRosati, SSánchez, CScannicchio, D ASchiavi, CSegura, EDe Seixas, J MSivoklokov, S YuSobreira, ASoluk, R AStefanidis, ESushkov, SSutton, MTapprogge, STarem, SThomas, ETouchard, FUsai, GVenda-Pinto, BVentura, AVercesi, VWengler, TWerner, PWheeler, S JWickens, F JWiedenmann, WWielers, MZobernig, GImplementation and Performance of the Seeded Reconstruction for the ATLAS Event Filter Selection SoftwareDetectors and Experimental TechniquesATL-DAQ-CONF-2005-032ATL-COM-DAQ-2005-026CERN-ATL-DAQ-CONF-2005-032ATLAS is one of the four LHC experiments that will start data taking in 2007, designed to cover a wide range of physics topics. The ATLAS trigger system has to cope with a rate of 40 MHz and 23 interactions per bunch crossing. It is divided in three different levels. The first one (hardware based) provides a signature that is confirmed by the the following trigger levels (software based) by running a sequence of algorithms and validating the signal step by step, looking only to the region of the space indicated by the first trigger level (seeding). In this paper, the performance of one of these sequences that run at the Event Filter level (third level) and is composed of clustering at the calorimeter, track reconstruction and matching.2005http://cds.cern.ch/record/84721310.1109/RTC.2005.1547532DAQ and Triggerhttp://cds.cern.ch/record/847213oai:cds.cern.ch:847213 engBosman, MMeessen, CNegri, ASegura, ESushkov, STouchard, FWheeler, S JDevelopment and Tests of the Event Filter for the ATLAS ExperimentDetectors and Experimental TechniquesATL-DAQ-CONF-2005-027ATL-COM-DAQ-2005-025CERN-ATL-DAQ-CONF-2005-027The Trigger and Data Acquisition (TDAQ) System of the ATLAS Experiment comprises three stages of event selection. The Event Filter (EF) is the third level trigger and is software implemented. Its primary goal is the final selection of interesting events with reduction of the event rate down to ~200 Hz acceptable by the mass storage. The EF System will be implemented as a set of independent commodity components Sub-Farms, each connected to the Event Builder subsystem to receive full events and on the other side to the Sub-Farm Output nodes, where the selected events are forwarded to mass storage. A distinctive feature of the Event Filter is its ability to use the full event data for selection directly based on the offline reconstruction and analysis algorithms. Besides the main duties on event triggering and data transportation, the EF is also able to provide additional functionalities, like monitoring of the selected events and online calibration of the ATLAS detectors. Significant design improvements are currently under development to provide these additional functionalities to the EF System. The Event Filter was deployed and tested in data triggering at the ATLAS Combined Test Beam at CERN in 2004. The EF is also subject to various tests on dedicated test-bed computer clusters, where both the EF functionalities and performance are studied. Special tests are being done when running the EF software components on the large-scale EF Farms, with hundreds of computers. This paper describes the current activities and plans on development and testing of the ATLAS Event Filter System.2005http://cds.cern.ch/record/847041DAQ and Triggerhttp://cds.cern.ch/record/847041oai:cds.cern.ch:847041 engAnjos, AArmstrong, SBaines, J T MBeck, H PBee, C PBiglietti, MBogaerts, J A CBosman, MBurckhart, DorisCaprini, MCaron, BCasado, M PCataldi, GCavalli, DCiobotaru, MComune, GConde, PCorso-Radu, ACrone, GDamazio, DDe Santo, ADíaz-Gómez, MDi Mattia, ADobson, MEllis, NickEmeliyanov, DEpp, BFalciano, SFerrari, RFrancis, DGadomski, SGameiro, SGaritaonandia, HGeorge, SGhete, VGoncalo, RGorini, BGruwé, MHaeberli, CHaller, JJoos, MKabana, SKazarov, AKhomich, AKilvington, GKirk, JKolos, SKonstantinidis, N PKootz, ALankford, ALehmann, GLowe, ALuminari, LMaeno, TMasik, JMeirosu, CMeessen, CMello, A GMoore, RMorettini, PNegri, ANikitin, NNisati, AOsuna, CPadilla, CPanikashvili, NParodi, FPasqualucci, EPérez-Réale, VPetersen, JPinfold, J LPinto, PQian, ZResconi, SRosati, SSánchez, CSantamarina-Rios, CScannicchio, D ASchiavi, CSegura, ESeixas, J MSivoklokov, S YuSloper, JSobreira, ASoloviev, ISoluk, R AStancu, SStefanidis, ESushkov, SSutton, MTapprogge, STarem, SThomas, ETouchard, FTremblet, LÜnel, GUsai, GVandelli, Wainer RVenda-Pinto, BVentura, AVercesi, VWengler, TWerner, PWheeler, S JWickens, F JWiedenmann, WWielers, MWiesmann, MYasu, YZobernig, GDeployment of the ATLAS High-Level TriggersDetectors and Experimental TechniquesATL-DAQ-CONF-2005-033ATL-COM-DAQ-2005-023CERN-ATL-DAQ-CONF-2005-033The ATLAS combined test beam in the second half of 2004 saw the first deployment of the ATLAS High-Level Triggers (HLT). The next steps are deployment on the pre-series farms in the experimental area during 2005, commissioning and cosmics tests in 2006 and collisions in 2007. This paper reviews the experience gained in the test beam, describes the current status and discusses the further enhancements to be made. We address issues related to the dataflow, selection algorithms, testing, software distribution, installation and improvements.2005http://cds.cern.ch/record/845661DAQ and Triggerhttp://cds.cern.ch/record/845661oai:cds.cern.ch:845661 doi:10.1109/RTC.2005.1547456engGadomski, SAbolins, MAlexandrov, IAmorim, APadilla-Aranda, ABadescu, EBarros, NBeck, H PBlair, RBurckhart-Chromek, DorisCaprini, MCiobotaru, MConde-Muíño, PCorso-Radu, ADi Girolamo, BDíaz-Gómez, MDobinson, Robert WDobson, MFerrari, RFerrer, M LFrancis, DGameiro, SGorini, BGruwé, MHaas, SHaeberli, CHauser, RHughes-Jones, R EJoos, MKazarov, AKlose, DKolos, SKotov, VLehmann, GMapelli, LMartin, BMcLaren, RMeirosu, CMineev, MNegri, APasqualucci, EPérez-Réale, VPetersen, JPrigent, DRyabov, YuSánchez, CSantamarina-Rios, CSchlereth, J LSloper, J ESoloviev, IStancu, STremblet, LÜnel, GVandelli, Wainer RWerner, PWheeler, SWiesmann, MYasu, YDeployment and use of the ATLAS DAQ in the Combined Test BeamDetectors and Experimental TechniquesATL-DAQ-CONF-2005-019ATL-COM-DAQ-2005-014The ATLAS collaboration at CERN operated a Combined Test Beam (CTB) from May until November 2004. The prototype of ATLAS Data Acquisition system (DAQ) was used to integrate other subsystems into a common CTB setup. Data were collected synchronously from all the ATLAS detectors, which represented nine different detector technologies. Electronics and software of the First Level Trigger were used to trigger the setup. Event selection algorithms of the High Level Trigger were integrated with the system and were tested with real detector data. A possibility to operate a remote Event Filter farm synchronized with ATLAS TDAQ was also tested. Event data, as well as detectors conditions data were made available for offline analysis.2005http://cds.cern.ch/record/84083810.1109/RTC.2005.1547456DAQ and Triggerhttp://cds.cern.ch/record/840838oai:cds.cern.ch:840838 engDos Anjos, AArmstrong, SBaines, J T MBee, C PBiglietti, MBogaerts, J A CBosman, MCarlino, GCaron, BCasado, M PCataldi, GCavalli, DComune, GConde, PConventi, FCrone, GDamazio, DDe Santo, ADíaz-Gómez, MDi Mattia, AEllis, NickEmeliyanov, DEpp, BFalciano, SGaritaonandia, HGeorge, SGhete, VGoncalo, RGorini, EHaller, JKabana, SKhomich, AKilvington, GKirk, JKonstantinidis, N PKootz, ALankford, A JLowe, ALuminari, LMaeno, TMasik, JMeessen, CMello, A GMoore, RMorettini, PNegri, ANikitin, NNisati, AOsuna, CPadilla, CPanikashvili, NParodi, FPasqualucci, EPérez-Réale, VPinfold, J LPinto, PPrimavera, MQian, ZResconi, SRosati, SSánchez, CSantamarina-Rios, CScannicchio, D ASchiavi, CSegura, EDe Seixas, J MSivoklokov, S YuSobreira, ASoluk, R ASpagnolo, SStefanidis, ESushkov, SSutton, MTapprogge, STarem, SThomas, ETouchard, FUsai, GVenda-Pinto, BVentura, AVercesi, VWengler, TWerner, PWheeler, S JWickens, F JWiedenmann, WWielers, MZobernig, GMuon Identification with the Event Filter of the ATLAS Experiment at CERN LHC'sDetectors and Experimental TechniquesATL-DAQ-CONF-2005-018ATL-COM-DAQ-2005-013The Large Hadron Collider at CERN offers unprecedented challenges to the design and construction of detectors and trigger/data acquisition systems. For ATLAS, a three level trigger system has been developed to extract interesting physics signatures with a 10^6 rate reduction. To accomplish this, components of physics analysis traditionally deferred to offline physics analysis must be embedded within the online trigger system. For the Muon trigger, the specific off-line algorithms MOORE (Muon Object Oriented REconstruction) and MuId (Muon Identification) have been adopted so far for the on-line use, imposing an operation in a Bayesian-like environment where only specific hypotheses must be validated. After a short review of the ATLAS trigger, the paper shows the general strategy of the Muon Identification and Selection accessing the full event data, or being seeded from results derived at a previous stage of the trigger chain.2005http://cds.cern.ch/record/837654DAQ and Triggerhttp://cds.cern.ch/record/837654oai:cds.cern.ch:837654 doi:10.5170/CERN-2005-002.250engSchiavi, CArmstrong, SDos Anjos, ABaines, J T MBee, C PBiglietti, MBogaerts, J A CBoisvert, VBosman, MCaron, BCasado, M PCataldi, GCavalli, DCervetto, MComune, GConde-Muíño, PDe Santo, ADíaz-Gómez, MDosil, MEllis, NickEmeliyanov, DEpp, BFalciano, SFarilla, AGeorge, SGhete, V MGonzález, SGrothe, MKabana, SKhomich, AKilvington, GKonstantinidis, N PKootz, ALowe, ALuminari, LMaeno, TMasik, JDi Mattia, AMeessen, CMello, A GMerino, GMoore, RMorettini, PNegri, ANikitin, NNisati, APadilla, CPanikashvili, NParodi, FPérez-Réale, VPinfold, J LPinto, PQiand, ZResconi, SRosati, SSánchez, CSantamarina-Rios, CScannicchio, D ASegura, EDe Seixas, J MSivoklokov, S YuSoluk, R AStefanidis, ESushkov, SSutton, MTapprogge, SThomas, ETouchard, FVenda-Pinto, BVentura, AVercesi, VWerner, PWheeler, SWickens, F JWiedenmann, WWielers, MZobernig, GImplementation and Performance of the High Level Trigger Electron and Photon Selection for the ATLAS Experiment at the LHCDetectors and Experimental TechniquesATL-DAQ-CONF-2005-014ATL-COM-DAQ-2005-012CERN-ATL-DAQ-CONF-2005-014The ATLAS experiment at the Large Hadron Collider (LHC) will face the challenge of efficiently selecting interesting candidate events in pp collisions at 14 TeV center of mass energy, while rejecting the enormous number of background events, stemming from an interaction rate of up to 10^9 Hz. The First Level trigger will reduce this rate to around O(100 kHz). Subsequently, the High Level Trigger (HLT), which is comprised of the Second Level trigger and the Event Filter, will need to further reduce this rate by a factor of O(10^3). The HLT selection is software based and will be implemented on commercial CPUs, using a common framework built on the standard ATLAS object oriented software architecture. In this paper an overview of the current implementation of the selection for electrons and photons in the HLT is given. The performance of this implementation has been evaluated using Monte Carlo simulations in terms of the efficiency for the signal channels, rate expected for the selection, data preparation times, and algorithm execution times. Besides the efficiency and rate estimates, some physics examples will be discussed, showing that the triggers are well adapted for the physics programme envisaged at LHC. The electron and photon trigger software is also being exercised at the ATLAS 2004 Combined Test Beam, where components from all ATLAS subdetectors are taking data together along the H8 SPS extraction line; from these tests a validation of the selection architecture chosen in a real on-line environment is expected.CERN2004http://cds.cern.ch/record/83039810.5170/CERN-2005-002.250DAQ and Triggerhttp://cds.cern.ch/record/830398oai:cds.cern.ch:830398 engGarvey, JHillier, S JMahout, GMoye, T HStaley, R JThomas, J PTypaldos, DWatkins, P MWatson, AAchenbach, RFöhlisch, FGeweniger, CHanke, PKluge, E EMahboubi, KMeier, KMeshkov, PRühr, FSchmitt, KSchultz-Coulon, H CAy, CBauss, BBelkin, ARieke, SSchäfer, UTapprogge, TTrefzger, TWeber, GAEisenhandler, E FLandon, MApostologlou, PBarnett, B MBrawn, I PDavis, A OEdwards, JGee, C N PGillman, A RMirea, APerera, V J OQian, WSankey, D P CBohm, CHellman, SHidvegi, ASilverstein, SBeam Test of the ATLAS Level-1 Calorimeter Trigger SystemDetectors and Experimental TechniquesATL-DAQ-CONF-2005-006ATL-COM-DAQ-2005-010CERN-ATL-DAQ-CONF-2005-006The Level-1 Calorimter Trigger consists of a Preprocessor (PP), a Cluster Processor (CP), and a Jet/Energy-sum Processor (JEP). The CP and JEP receive digitised trigger-tower data from the Preprocessor and produce Region-of-Interest (RoIs) and trigger multiplicities. The latter are sent in real time to the Central Trigger Processor (CTP) where the Level-1 decision is made. On receipt of a Level-1 Accept, Readout Driver Modules (RODs), provide intermediate results to the data acquisition (DAQ) system for monitoring and diagnostic purpose. RoI information is sent to the RoI builder (RoIB) to help reduce the amount of data required for the Level-2 Trigger The Level-1 Calorimeter Trigger System at the test beam consisted of 1 Preprocessor module, 1 Cluster Processor Module, 1 Jet/Energy Module and 2 Common Merger Modules. Calorimeter energies were sucessfully handled thourghout the chain and trigger object sent to the CTP. Level-1 Accepts were sucessfully produced and used to drive the readout path. Online diagnostics were made using 4 RODs. Energy histograms were plotted and the integrity of data between the different modules was checked. All ATLAS detectors in the test beam were able to build full events based on triggers delivered by the Calorimeter Trigger System.2005http://cds.cern.ch/record/824270DAQ and Triggerhttp://cds.cern.ch/record/824270oai:cds.cern.ch:824270 doi:10.5170/CERN-2005-002.334engBiglietti, MArmstrong, SAssamagan, Ketevi ABaines, J T MBee, C PBellomo, MBogaerts, J A CBoisvert, VBosman, MCaron, BCasado, M PCataldi, GCavalli, DCervetto, MComune, GConde, PConde-Muíño, PDe Santo, ADe Seixas, J MDi Mattia, ADos Anjos, ADosil, MDíaz-Gómez, MEllis, NickEmeliyanov, DEpp, BFalciano, SFarilla, AGeorge, SGhete, V MGonzález, SGrothe, MKabana, SKhomich, AKilvington, GKonstantinidis, N PKootz, ALowe, ALuminari, LMaeno, TMasik, JMeessen, CMello, A GMerino, GMoore, RMorettini, PNegri, ANikitin, N VNisati, APadilla, CPanikashvili, NParodi, FPinfold, J LPinto, PPrimavera, MPérez-Réale, VQian, ZResconi, SRosati, SSantamarina-Rios, CScannicchio, D ASchiavi, CSegura, ESivoklokov, S YuSoluk, R AStefanidis, ESushkov, SSutton, MSánchez, CTapprogge, StefanThomas, ETouchard, FVenda-Pinto, BVentura, AVercesi, VWerner, PWheeler, SWickens, F JWiedenmann, WWielers, MZobernig, GMuon Event Filter Software for the ATLAS Experiment at LHCDetectors and Experimental TechniquesATL-DAQ-CONF-2005-008ATL-COM-DAQ-2005-005At LHC the 40 MHz bunch crossing rate dictates a high selectivity of the ATLAS Trigger system, which has to keep the full physics potential of the experiment in spite of a limited storage capability. The level-1 trigger, implemented in a custom hardware, will reduce the initial rate to 75 kHz and is followed by the software based level-2 and Event Filter, usually referred as High Level Triggers (HLT), which further reduce the rate to about 100 Hz. In this paper an overview of the implementation of the offline muon recostruction algortihms MOORE (Muon Object Oriented REconstruction) and MuId (Muon Identification) as Event Filter in the ATLAS online framework is given. The MOORE algorithm performs the reconstruction inside the Muon Spectrometer providing a precise measurement of the muon track parameters outside the calorimeters; MuId combines the measurements of all ATLAS sub-detectors in order to identify muons and provides the best estimate of their momentum at the production vertex. In the HLT implementation the muon reconstruction can be executed in "full scan mode", performing pattern recognition in the whole muon spectrometer, or in the "seeded mode", taking advantage of the results of the earlier trigger levels.An estimate of the execution time will be presented along with the performances in terms of efficiency, momentum resolution and rejection power for muons coming from hadron decays and for fake muon tracks, due to accidental hit correlations in the high background environment of the experiment.CERN2004http://cds.cern.ch/record/82078310.5170/CERN-2005-002.334DAQ and Triggerhttp://cds.cern.ch/record/820783oai:cds.cern.ch:820783 engVentura, AArmstrong, SAssamagan, Ketevi ABaines, J T MBee, C PBellomo, MBiglietti, MBogaerts, J A CBoisvert, VBosman, MCarlino, GCaron, BCasado, M PCataldi, GCavalli, DCervetto, MComune, GConde-Muíño, PConventi, FDe Santo, ADe Seixas, J MDíaz-Gómez, MDi Mattia, ADos Anjos, ADosil, MEllis, NickEmeliyanov, DEpp, BFalciano, SFarilla, AGeorge, SGhete, V MGonzález, SGrothe, MKabana, SKhomich, AKilvington, GKonstantinidis, N PKootzw, ALowe, ALuminari, LMaeno, TMasik, JMeessen, CMello, A GMerino, GMoore, RMorettini, PNegri, ANikitin, N VNisati, APadilla, CPanikashvili, NParodi, FPérez-Réale, VPinfold, J LPinto, PPrimavera, MQian, ZResconi, SRosati, SSánchez, CSantamarina-Rios, CScannicchio, D ASchiavi, CSegura, ESivoklokov, S YuSoluk, R AStefanidis, ESushkov, SSutton, MTapprogge, StefanThomas, ETouchard, FVenda-Pinto, BVercesi, VWerner, PImplementation and Performance of the Event Filter Muon Selection for the ATLAS experiment at LHCDetectors and Experimental TechniquesATL-DAQ-CONF-2005-015ATL-COM-DAQ-2005-002The ATLAS Trigger system is composed of three levels: an initial hardware trigger level (LVL1) followed by two software-based stages (LVL2 trigger and Event Filter) included in the High Level Trigger (HLT) and implemented on processor farms. The LVL2 trigger starts from LVL1 information concerning pointers to restricted so-called Regions of Interest (ROI) and performs event selection by means of optimized algorithms. If the LVL2 is passed, the full event is built and sent to the Event Filter (EF) algorithms for further selection and classification. After that, events are finally collected and put into mass storage for subsequent physics analysis. Even if many differences arise in the requirements and in the interfaces between the two HLT stages, they have a coherent approach to event selection. Therefore, the design of a common core software framework has been implemented in order to allow the HLT architecture to be flexible to changes (background conditions, luminosity, description of the detector, etc.). Algorithms working in the Event Filter are designed to work not only in a general purpose or exclusive mode, but they have been implemented in such a way to process given trigger hypotheses produced at a previous stage in the HLT dataflow. This is done by acting in separate steps, so that decisions to go further in the process are taken at every new step. An overview of the HLT processing steps is given and the working principles of the EF offline algorithms for muon reconstruction and identification (MOORE and MuId) are discussed in deeper detail. The reconstruction performances of these algorithms in terms of efficiency, momentum resolution, rejection power and execution times on several samples of simulated single muon events are presented, also taking into account the high background environment that is expected for ATLAS.2005http://cds.cern.ch/record/820770DAQ and Triggerhttp://cds.cern.ch/record/820770oai:cds.cern.ch:820770 doi:10.5170/CERN-2005-002.246engBaines, J T MDrevermann, HEmeliyanov, DKonstantinidis, N PParodi, FSchiavi, CSutton, MFast Tracking for the ATLAS LVL2 TriggerDetectors and Experimental TechniquesATL-DAQ-CONF-2005-001ATL-COM-DAQ-2004-028We present a set of algorithms for fast track reconstruction at the second level (LVL2) trigger of ATLAS, using three-dimensional space points (= hits) from the silicon trackers. The strategy is to determine the position z_0 of the interesting pp interaction along the beam axis prior to any track reconstruction and then retain only groups of hits which point back to that z_0 and perform combinatorial tracking only inside those groups. We give results and discuss the advantages of this approach, which is generic enough to be applicable to other multi-collision experiments. We also make a qualitative comparison with a complementary approach which is based on Look-Up Tables (LUT) and is also used in ATLAS.CERN2005http://cds.cern.ch/record/80314310.5170/CERN-2005-002.246DAQ and Triggerhttp://cds.cern.ch/record/803143oai:cds.cern.ch:803143 doi:10.5170/CERN-2005-002.111engConde-Muíño, PArmstrong, SDos Anjos, ABaines, J T MBee, C PBiglietti, MBogaerts, J A CBoisvert, VBosman, MCaron, BCasado, M PCataldi, GCavalli, DCervetto, MComune, GDe Santo, ADíaz-Gómez, MDosil, MEllis, NickEmeliyanov, DEpp, BFalciano, SFarilla, AGeorge, SGhete, V MGonzález, SGrothe, MKabana, SKhomich, AKilvington, GKonstantinidis, N PKootz, ALowe, ALuminari, LMaeno, TMasik, JDi Mattia, AMeessen, CMello, A GMerino, GMoore, RMorettini, PNegri, ANikitin, N VNisati, APadilla, CPanikashvili, NParodi, FPérez-Réale, VPinfold, J LPinto, PQian, ZResconi, SRosati, SSánchez, CSantamarina-Rios, CScannicchio, D ASchiavi, CSegura, EDe Seixas, J MSivoklokov, S YuSoluk, R AStefanidis, ESushkov, SSutton, MTapprogge, StefanThomas, ETouchard, FVenda-Pinto, BVercesi, VWerner, PWheeler, SWickens, F JWiedenmann, WWielers, MZobernig, GPortable Gathering System for Monitoring and Online Calibration at ATLASDetectors and Experimental TechniquesATL-DAQ-2004-014CERN-ATL-DAQ-2004-014ATL-COM-DAQ-2004-020CERN-ATL-COM-DAQ-2004-020During the runtime of any experiment, a central monitoring system that detects problems as soon as they appear has an essential role. In a large experiment, like ATLAS, the online data acquisition system is distributed across the nodes of large farms, each of them running several processes that analyse a fraction of the events. In this architecture, it is necessary to have a central process that collects all the monitoring data from the different nodes, produces full statistics histograms and analyses them. In this paper we present the design of such a system, called the gatherer. It allows to collect any monitoring object, such as histograms, from the farm nodes, from any process in the DAQ, trigger and reconstruction chain. It also adds up the statistics, if required, and processes user defined algorithms in order to analyse the monitoring data. The results are sent to a centralized display, that shows the information online, and to the archiving system, triggering alarms in case of problems. The innovation of this system is that conceptually it abstracts several underlying communication protocols, being able to talk with different processes using different protocols at the same time and, therefore, providing maximum flexibility. The software is easily adaptable to any trigger-DAQ system. The first prototype of the gathering system has been implemented for ATLAS and has been running during this year's combined test beam. An evaluation of this first prototype will also be presented.CERN2004http://cds.cern.ch/record/79746010.5170/CERN-2005-002.111http://cds.cern.ch/record/797460oai:cds.cern.ch:797460 doi:10.1140/epjc/s10052-007-0239-1engMoraes, AButtar, CDawson, IPrediction for minimum bias and the underlying event at LHC energiesDetectors and Experimental TechniquesSN-ATLAS-2006-057In this report we investigate the models employed by PYTHIA and PHOJET Monte Carlo event generators used to describe soft interactions in hadron-hadron collisions. The prime aim of this study is to predict minimum bias and underlying event levels of particle production and event activity for the LHC as accurately as these models allow us, thus providing a good description of the event environment in simulations. Focusing on a wide range of measurements dominated by soft interactions in proton-proton and proton-anti-proton collisions, one of the aims of this study is to check the consistency of these models when compared to data and evaluate how accurate their descriptions of low-pT processes are. Based on comparisons to a wide range of minimum bias and underlying event data we present a tuning for PYTHIA6.214 and compare it to other PYTHIA tunings. Our proposed tuning for PYTHIA6.214 has been used for the ATLAS Data Challenge productions.2005http://cds.cern.ch/record/87225710.1140/epjc/s10052-007-0239-1Physicshttp://cds.cern.ch/record/872257oai:cds.cern.ch:872257Accepted as Scientific Note SN-ATLAS-2006-057 eng Díaz-Gómez, M Padilla, C Riu, I Peres-Realez, V Performance of the Second Level Trigger Electron Selection Algorithms with the 2004 ATLAS Combined Test Beam Data Detectors and Experimental Techniques ATL-DAQ-INT-2005-002 ATL-COM-DAQ-2005-040 CERN-ATL-COM-DAQ-2005-040 During 2004, ATLAS performed a combined test beam where pieces of all the detectors with final or almost final readout electronics took data in common using a prototype of the complete trigger and data acquisition system. The setup resembled a wedge of the final ATLAS detector. The study presented here uses electron and pion data taken in the combined test beam to study the performance of the algorithms used at the second level trigger to select electrons with high efficiency while keeping a low pion fake rate. This is the last chance that a high level trigger performance study with real data can be done before ATLAS operation starts. 2005 http://cds.cern.ch/record/907902 DAQ and Trigger http://cds.cern.ch/record/907902 doi:10.1109/NSSMIC.2005.1596230engGoncalo, RArmstrong, SBaines, J T MCasado, M PClark, AConde-Muíño, PDamazio, DDe Santo, ADíaz-Gómez, MEmeliyanov, DGaumer, OGeorge, SKhomich, AKilvington, GKonstantinidis, N PKootz, ALowe, AMcMahon, TMello, A GOsuna, CPadilla, CParodi, FPérez-Réale, VPretzl, KSantamarina-Rios, CSchiavi, CSivoklokov, S YuStefanidis, ESutton, MThomas, ETeixeira-Dias, PWatson, AWielers, MWoehring, E EWu, XOverview of the High-Level Trigger Electron and Photon Selection for the ATLAS Experiment at the LHCDetectors and Experimental TechniquesATL-DAQ-CONF-2005-036ATL-COM-DAQ-2005-042CERN-ATL-DAQ-CONF-2005-036The ATLAS experiment is one of two general purpose experiments to start running at the Large Hadron Collider in 2007. The short bunch crossing period of 25ns and the large background of soft-scattering events overlapped in each bunch crossing pose serious challenges that the ATLAS trigger must overcome in order to efficiently select interesting events. The ATLAS trigger consists of a hardware-based First-Level Trigger and of a software-based High-Level Trigger, which can be further divided into the Second-Level Trigger and the Event Filter. This paper presents the current state of development of methods to be used in the High-Level Trigger to select events containing electrons or photons with high transverse momentum. The performance of these methods is presented, resulting from both simulation studies, timing measurements, and test beam studies.2005http://cds.cern.ch/record/91228410.1109/NSSMIC.2005.1596230DAQ and Triggerhttp://cds.cern.ch/record/912284oai:cds.cern.ch:912284Re-submitted to CDS with corrections to author list wrt ATL-COM-DAQ-2005-039/041. engKersevan, Borut PMalawski, MRichter-Was, ElzbietaProspects for observing an invisibly decaying Higgs boson in the t anti-t H production at LHCDetectors and Experimental TechniquesATL-PHYS-2003-028The prospects for observing an invisibly decaying Higgs boson in the t anti-t H production at LHC are discussed. An isolated lepton, reconstructed hadronic top-quark decay, two identified b-jets and large missing transverse energy are proposed as the final state signature for event selection. Only the Standard Model backgrounds are taken into account. It is shown that the t anti-t Z, t anti-t W, b anti-b Z and b anti-b W backgrounds can individually be suppressed below the signal expectation. The dominant source of background remains the t anti-t production. The key for observability will be an experimental selection which allows further suppression of the contributions from the t anti-t events with one of the top-quarks decaying into a tau lepton.2003-04-24http://cds.cern.ch/record/685475Physicshttp://cds.cern.ch/record/685475oai:cds.cern.ch:685475revised version number 2 submitted on 2003-07-28 16:59:35 engAbramowicz, HAbt, IAdamczyk, LAdamus, MAdler, VAghuzumtsyan, GAllfrey, P DAntonioli, PAntonov, AArneodo, MBailey, D SBamberger, ABarakbaev, A NBarbagli, GBarbi, MBari, GBarreiro, FBartsch, DBasile, MBehrens, UBell, M ABellagamba, LBellan, P MBenen, ABertolin, ABhadra, SBloch, IBold, TBoos, E GBorras, KBoscherini, DBrock, IBrook, N HBrugnera, RBrümmer, NBruni, ABruni, GBussey, P JButterworth, J MBüttner, CBylsma, BCaldwell, ACapua, MCara Romeo, GCarli, TCarlin, RCassel, D GCatterall, C DChekanov, SChwastowski, JCiborowski, JCiesielski, RCifarelli, LuisaCindolo, FCole, J ECollins-Tooth, CContin, ACooper-Sarkar, A MCoppola, NCorradi, MCorriveau, FCosta, MCottrell, ACui, YD'Agostini, GDal Corso, FDanilov, PDe Pasquale, SDementiev, R KDerrick, MDevenish, R C EDhawan, SDobur, DDolgoshein, B ADoyle, A TDrews, GDurkin, L SDusini, SEisenberg, YErmolov, P FEskreys, AndrzejEverett, AFerrando, JFerrero, M IFigiel, JFoster, BFoudas, CFourletov, SFourletova, JFry, CGabareen, AGalas, AGallo, EGarfagnini, AGeiser, AGenta, CGialas, IGiusti, PGladilin, L KGladkov, DGlasman, CGöbel, FGoers, SGoncalo, RGonzález, OGosau, TGöttlicher, PGrabowska-Bold, IGraciani-Díaz, RGrigorescu, GGrijpink, SGroys, MGrzelak, GGutsche, OGwenlan, CHaas, THain, WHall-Wilton, RHamatsu, RHamilton, JHanlon, SHart, CHartmann, HHartner, GHeaphy, E AHeath, G PHelbich, MHilger, EHochman, DHolm, UHorn, CIacobucci, GIga, YIrrgang, PJakob, H PJiménez, MJones, T WKagawa, SKahle, BKaji, HKananov, SKarshon, UKarstens, FKasemann, MKataoka, MKatkov, I IKcira, DKeramidas, AKhein, L AKim, J YKind, OKisielewska, DKitamura, SKoffeman, EKohno, TKooijman, PKoop, TKorzhavina, I AKotanski, AKötz, UKowal, A MKowalski, HKramberger, GKreisel, AKrumnack, NKulinski, PKuze, MKuzmin, V ALabarga, LLammers, SLelas, DLevchenko, B BLevy, ALi, LLightwood, M SLim, HLimentani, SLing, T YLiu, CLiu, XLöhr, BLohrmann, ELoizides, J HLong, K RLonghin, ALukasik, JLukina, O YuLuzniak, PMa, K JMaddox, EMagill, SMalka, JMankel, RMargotti, AMarini, GMartin, J FMartínez, MMastroberardino, AMatsuzawa, KMattingly, M C KMelzer-Pellmann, I AMenary, S RMetlica, FMeyer, UMiglioranzi, SMilite, MMirea, AMonaco, VMontanari, AMusgrave, BNagano, KNamsoo, TNania, RNguyen, C NNigro, ANing, YNoor, UNotz, DNowak, R JNuncio-Quiroz, A EOh, B YOlkiewicz, KOta, OPadhi, SPalmonari, FPatel, SPaul, EPavel, UsanPawlak, J MPelfer, P GPellegrino, APesci, APiotrzkowski, KPlamondon, MPlucinsky, P PPokrovskiy, N SPolini, AProskuryakov, A SPrzybycien, M BRautenberg, JRaval, AReeder, D DRen, ZRenner, RRepond, JRi, Y DRinaldi, LRobins, SRosin, MRuspa, MRyan, PSacchi, RSalehi, HSantamarta, RSartorelli, GSavin, A ASaxon, D HSchagen, SSchioppa, MSchlenstedt, SSchleper, PSchmidke, W BSchneekloth, USchörner-Sadenius, TSciulli, FShcheglova, L MSkillicorn, I OSlominski, WSmith, W HSoares, MSolano, ASon, DSosnovtsev, V VStairs, D GStanco, LStandage, JStifutkin, AStonjek, SStopa, PStösslein, UStraub, P BSuchkov, SSusinno, GSuszycki, LSutiak, JSutton, M RSztuk, JSzuba, DSzuba, JTapper, A DTargett-Adams, CTassi, ETawara, TTerron, JTiecke, H GTokushuku, KTsurugai, TTurcato, MTymieniecka, TTyszkiewicz, AUkleja, AUkleja, JVázquez, MVlasov, N NVoss, K CWalczak, RWalsh, RWang, MWhitmore, J JWhyte, JWichmann, KWick, KWiggers, LWills, H HWing, MWlasenko, MWolf, GYagues-Molina, A GYamada, SYamazaki, YYoshida, RYoungman, CZambrana, MZawiejski, LZeuner, WZhautykov, B OZhou, CZichichi, AZiegler, AZotkin, D SZotkin, S ADe Favereau, JDe Wolf, EDel Peso, JAn NLO QCD analysis of inclusive cross-section and jet-production data from the ZEUS experimentParticle Physics - Phenomenologyhep-ph/0503274DESY-05-050DESY-2005-050The ZEUS inclusive differential cross-section data from HERA, for charged and neutral current processes taken with e+ and e- beams, together with differential cross-section data on inclusive jet production in e+ p scattering and dijet production in \gamma p scattering, have been used in a new NLO QCD analysis to extract the parton distribution functions of the proton. The input of jet data constrains the gluon and allows an accurate extraction of \alpha_s(M_Z) at NLO; \alpha_s(M_Z) = 0.1183 \pm 0.0028(exp.) \pm 0.0008(model) An additional uncertainty from the choice of scales is estimated as \pm 0.005. This is the first extraction of \alpha_s(M_Z) from HERA data alone.2005-03-29http://cds.cern.ch/record/829798http://cds.cern.ch/record/829798oai:cds.cern.ch:829798 engBreitweg, JChekanov, SDerrick, MalcolmKrakauer, D AMagill, SMusgrave, BPellegrino, ARepond, JStanek, RYoshida, RAntonioli, PBari, GBasile, MBellagamba, LBoscherini, DBruni, ABruni, GCara Romeo, GCifarelli, LuisaCindolo, FContin, ACorradi, MDe Pasquale, SGiusti, PIacobucci, GLevi, GMargotti, AMassam, ThomasNania, RPalmonari, FPesci, ABornheim, ABrock, ICoboken, KCrittenden, James ArthurDeffner, RHeinloth, KHilger, EIrrgang, PJakob, H PKappes, AKatz, U FKerger, RPaul, ERautenberg, JSchnurbusch, HStifutkin, ATandler, JVoss, K CWeber, AWieber, HBailey, D SBarret, OBrook, N HFoster, BHeath, G PHeath, H FRodrigues, EScott, JTapper, R JCapua, MMastroberardino, ASchioppa, MSusinno, GJeoung, H YKim, J YLee, J HLim, I TMa, K JPac, M YCaldwell, ALiu, WLiu, XMellado, BPaganis, SSampson, SSchmidke, W BChwastowski, JEskreys, AndrzejFigiel, JKlimek, K HOlkiewicz, KPiotrzkowski, KStopa, PZawiejski, LBednarek, BJelen, KKisielewska, DKowal, A MKowalski, TPrzybycien, M BSuszycki, LSzuba, DBauerdick, L A TBehrens, UBienlein, J KBorras, KChiochia, VDannheim, DDesler, KDrews, GFox-Murphy, AFricke, UGöbel, FGoers, SGöttlicher, PGraciani, RHaas, THain, WHartner, G FHebbel, KHillert, SKoch, WKötz, UKowalski, HLabes, HLöhr, BMankel, RMartens, JMartínez, MMilite, MMoritz, MNotz, DPetrucci, M CPolini, ARohde, MSavin, A ASchneekloth, USelonke, FSievers, MStonjek, SWolf, GWollmer, UYoungman, CZeuner, WColdewey, CLópez-Duran-Viani, AMeyer, ASchlenstedt, SStraub, P BBarbagli, GGallo, EParenti, APelfer, P GBamberger, AndreasBenen, ACoppola, NEisenhardt, SMarkun, PRaach, HWölfle, SBussey, Peter JBell, MDoyle, A TGlasman, CLee, S WLupi, AMacDonald, NMcCance, G JSaxon, D HSinclair, L ESkillicorn, Ian OWaugh, RBohnet, IGendner, NHolm, UMeyer-Larsen, ASalehi, HWick, KCarli, TGarfagnini, AGialas, IGladilin, L KKcira, DKlanner, RobertLohrmann, EGoncalo, RLong, K RMiller, D BTapper, A DWalker, RCloth, PFilges, DIshii, TKuze, MNagano, KTokushuku, KYamada, SYamazaki, YAhn, S HLee, S BPark, S KLim, HSon, DBarreiro, FGarcía, GGonzález, OLabarga, LDel Peso, JRedondo, ITerron, JVázquez, M EBarbi, M SCorriveau, FHanna, D SOchs, APadhi, SStairs, D GWing, MTsurugai, TAntonov, ABashkirov, VDanilov, M VDolgoshein, B AGladkov, DSosnovtsev, V VSuchkov, SDementev, R KErmolov, P FGolubkov, Yu AKatkov, I IKhein, L AKorotkova, N AKorzhavina, I AKuzmin, V ALukina, O YuProskuryakov, A SShcheglova, L MSolomin, A NVlasov, N NZotkin, S ABokel, CBotje, MBrümmer, NEngelen, JGrijpink, SKoffeman, EKooijman, P MSchagen, SVan Sighem, ATassi, ETiecke, H GTuning, NVelthuis, J JVossebeld, Joost HermanWiggers, LDe Wolf, EBylsma, BDurkin, L SGilmore, JGinsburg, C MKim, C LLing, T YBoogert, SCooper-Sarkar, A MDevenish, R C EGrosse-Knetter, JMatsushita, TRuske, OSutton, M RWalczak, RBertolin, ABrugnera, RCarlin, RDal Corso, FDusini, SLimentani, SLonghin, APosocco, MStanco, LTurcato, MAdamczyk, LIannotti, LOh, B YOkrasinski, J RSaull, P R BToothacker, W SWhitmore, J JIga, YD'Agostini, GiulioMarini, GNigro, ACormack, CHart, J CMcCubbin, N AShah, T PEpperson, D EHeusch, C ASadrozinski, H F WSeiden, AWichmann, RWilliams, D CMeasurement of dijet cross sections for events with a leading neutron in photoproduction at HERAParticle Physics - Experimenthep-ex/0010019DESY-2000-142DESY-00-142Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e^+ + p --> e^+ + n + jet + jet + X_r have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb^{-1}. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies E^{jet}_T > 6 GeV, neutron energy E_n > 400 GeV, and neutron production angle theta_n < 0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model.2000-10-10http://cds.cern.ch/record/468269http://cds.cern.ch/record/468269oai:cds.cern.ch:468269 engBreitweg, JChekanov, SDerrick, MalcolmKrakauer, D AMagill, SMusgrave, BPellegrino, ARepond, JStanek, RYoshida, RMattingly, M C KAbbiendi, GAnselmo, FAntonioli, PBari, GBasile, MBellagamba, LBoscherini, DBruni, ABruni, GCara Romeo, GCastellini, GCifarelli, LuisaCindolo, FContin, ACoppola, NCorradi, MDe Pasquale, SGiusti, PIacobucci, GLaurenti, GLevi, GMargotti, AMassam, ThomasNania, RPalmonari, FPesci, APolini, ASartorelli, GZamora-Garcia, Yu EZichichi, AAmelung, CBornheim, ABrock, ICoboken, KCrittenden, James ArthurDeffner, RHartmann, HHeinloth, KHilger, EIrrgang, PJakob, H PKappes, AKatz, U FKerger, RPaul, ESchnurbusch, HStifutkin, ATandler, JVoss, K CWeber, AWieber, HBailey, D SBarret, OBrook, N HFoster, BHeath, G PHeath, H FMcFall, J DPiccioni, DRodrigues, EScott, JTapper, R JCapua, MMastroberardino, ASchioppa, MSusinno, GJeoung, H YKim, J YLee, J HLim, I TMa, K JPac, M YCaldwell, ALiu, WLiu, XMellado, BPaganis, SSampson, SSchmidke, W BSciulli, FChwastowski, JEskreys, AndrzejFigiel, JKlimek, K HOlkiewicz, KPiotrzkowski, KPrzybycien, M BStopa, PZawiejski, LBednarek, BJelen, KKisielewska, DKowal, A MKowalski, TRulikowska-Zarebska, ESuszycki, LSzuba, DKotanski, AndrzejBauerdick, L A TBehrens, UBienlein, J KBurgard, CDannheim, DDesler, KDrews, GFox-Murphy, AFricke, UGöbel, FGöttlicher, PGraciani, RHaas, THain, WHartner, G FHasell, DHebbel, KJohnson, K FKasemann, MKoch, WKötz, UKowalski, HLindemann, LLöhr, BMartínez, MMilite, MMonteiro, TMoritz, MNotz, DPelucchi, FPetrucci, M CRohde, MSaull, P R BSavin, A ASchneekloth, USelonke, FSievers, MStonjek, STassi, EWolf, GWollmer, UYoungman, CZeuner, WColdewey, CLópez-Duran-Viani, AMeyer, ASchlenstedt, SStraub, P BBarbagli, GGallo, EPelfer, P GMaccarrone, G DVotano, LBamberger, AndreasBenen, AEisenhardt, SMarkun, PRaach, HWölfle, SBussey, Peter JBell, MDoyle, A TLee, S WLupi, AMacDonald, NMcCance, G JSaxon, D HSinclair, L ESkillicorn, Ian OWaugh, RBohnet, IGendner, NHolm, UMeyer-Larsen, ASalehi, HWick, KGarfagnini, AGialas, IGladilin, L KKcira, DKlanner, RobertLohrmann, EPoelz, GZetsche, FGoncalo, RLong, K RMiller, D BTapper, A DWalker, RMallik, UCloth, PFilges, DIshii, TKuze, MNagano, KTokushuku, KYamada, SYamazaki, YAhn, S HLee, S BPark, S KLim, HPark, I HSon, DBarreiro, FGarcía, GGlasman, CGonzález, OLabarga, LDel Peso, JRedondo, ITerron, JBarbi, M SCorriveau, FHanna, D SOchs, APadhi, SRiveline, MStairs, D GWing, MTsurugai, TAntonov, ABashkirov, VDanilov, M VDolgoshein, B AGladkov, DSosnovtsev, V VSuchkov, SDementev, R KErmolov, P FGolubkov, Yu AKatkov, I IKhein, L AKorotkova, N AKorzhavina, I AKuzmin, V ALukina, O YuProskuryakov, A SShcheglova, L MSolomin, A NVlasov, N NZotkin, S ABokel, CBotje, MBrümmer, NEngelen, JGrijpink, SKoffeman, EKooijman, P MSchagen, SVan Sighem, ATiecke, H GTuning, NVelthuis, J JVossebeld, Joost HermanWiggers, LDe Wolf, EAcosta, DBylsma, BDurkin, L SGilmore, JGinsburg, C MKim, C LLing, T YBoogert, SCooper-Sarkar, A MDevenish, R C EGrosse-Knetter, JMatsushita, TQuadt, ARuske, OSutton, M RWalczak, RBertolin, ABrugnera, RCarlin, RDal Corso, FDosselli, UDusini, SLimentani, SMorandin, MPosocco, MStanco, LStroili, RTurcato, MVoci, CAdamczyk, LIannotti, LOh, B YOkrasinski, J RToothacker, W SWhitmore, J JIga, YD'Agostini, GiulioMarini, GNigro, ACormack, CHart, J CMcCubbin, N AShah, T PEpperson, D EHeusch, C ASadrozinski, H F WSeiden, AWichmann, RWilliams, D CPavel, NAbramowicz, HDagan, SKananov, SKreisel, ALevy, AAbe, TFusayasu, TUmemori, KYamashita, THamatsu, RHirose, TInuzuka, MKitamura, SNishimura, TArneodo, MCartiglia, NCirio, RCosta, MFerrero, M IMaselli, SMonaco, VPeroni, CRuspa, MSacchi, RSolano, AStaiano, ADardo, MBailey, D CFagerstroem, C PGalea, RKoop, TLevman, G MMartin, J FOrr, R SPolenz, SSabetfakhri, ASimmons, DButterworth, J MCatterall, C DHayes, M EHeaphy, E AJones, T WLane, J BWest, B JCiborowski, JCiesielski, RGrzelak, GNowak, R JPawlak, J MPawlak, RSmalska, BTymieniecka, TWróblewski, A KZakrzewski, J AZarnecki, A FAdamus, MGadaj, TDeppe, OEisenberg, YHochman, DKarshon, UBadgett, W FChapin, DCross, RFoudas, CMattingly, S E KReeder, D DSmith, W HVaiciulis, A WWildschek, TWodarczyk, MDeshpande, A ADhawan, S KHughes, V WBhadra, SCole, J EFrisken, W RHall-Wilton, RKhakzad, MMenary, S RMeasurement of the Proton Structure Function $F_{2}$ at Very Low $Q^{2}$ at HERAParticle Physics - Experimenthep-ex/0005018DESY-2000-071DESY-00-071A measurement of the proton structure function F_2(x,Q^2) is presented in the kinematic range 0.045 GeV^2 < Q^2 < 0.65 GeV^2 and 6*10^{-7} < x < 1*10^{-3}. The results were obtained using a data sample corresponding to an integrated luminosity of 3.9pb^-1 in e^+p reactions recorded with the ZEUS detector at HERA. Information from a silicon-strip tracking detector, installed in front of the small electromagnetic calorimeter used to measure the energy of the final-state positron at small scattering angles, together with an enhanced simulation of the hadronic final state, has permitted the extension of the kinematic range beyond that of previous measurements. The uncertainties in F_2 are typically less than 4%. At the low Q^2 values of the present measurement, the rise of F_2 at low x is slower than observed in HERA data at higher Q^2 and can be described by Regge theory with a constant logarithmic slope. The dependence of F_2 on Q^2 is stronger than at higher Q^2 values, approaching, at the lowest Q^2 values of this measurement, a region where F_2 becomes nearly proportional to Q^2.2000-05-11http://cds.cern.ch/record/437616http://cds.cern.ch/record/437616oai:cds.cern.ch:437616 engCammin, JSchumacher, MThe ATLAS discovery potential for the channel ttH, H to bbDetectors and Experimental TechniquesATL-PHYS-2003-024The production of a light Standard Model Higgs boson in association with a top quark-pair at the LHC is studied with the fast simulation of the ATLAS detector. The Higgs boson is assumed to decay into bbbar, one top-quark to decay into lnub and the other top-quark into jjb, leading to a complex final state of 1 isolated lepton, missing transverse momentum, and 6 jets of which 4 jets are b-jets. The full reconstruction of the final state is necessary to minimize the combinatorial background from assigning two out of the four b-jets to the Higgs boson decay and to discriminate the signal process from the large background from top quark-pairs with additional jets. Two methods for the analysis of this channel are presented: A `classical' reconstruction which is based on the procedure developed in the context of the ATLAS detector and physics performance TDR, and an improved method which makes use of likelihood techniques.2003-06-25http://cds.cern.ch/record/685523Physicshttp://cds.cern.ch/record/685523oai:cds.cern.ch:685523revised version number 1 submitted on 2003-08-14 08:08:35 Pernegger, HeinzInner Detector installation of ATLAS SCT and TRT barrel into the ATLAS cavernATLASATL-PHO-INDET-2006-004Transport of ATLAS Inner Detector SCT and TRT Barrels from SR1 to the ATLAS cavern Installation of SCT and TRT Barrel into the ATLAS cryostat2006http://cds.cern.ch/record/985309http://cds.cern.ch/record/985309oai:cds.cern.ch:985309ATLAS Collection. Marcelloni Oliveira, CThe last Toroid getting down to be installedATLASATL-PHO-OREACH-2005-0062005http://cds.cern.ch/record/905576http://cds.cern.ch/record/905576oai:cds.cern.ch:905576ATLAS Collection. Maximilien BriceInstalling the ATLAS calorimeterExperiments and TracksCERN-EX-0511013The eight toroid magnets can be seen surrounding the barrel calorimeter with its integrated solenoid that is later moved into the middle of the detector. This calorimeter will measure the energies of particles produced when protons collide in the centre of the detector. Roger Ruber (KEK), leading the solenoid commissioning at CERN, standing in the middle of the barrel toroid.2005-11-04http://cds.cern.ch/record/910381http://cds.cern.ch/record/910381oai:cds.cern.ch:910381