D. Damazio

Radiation qualification of the front-end electronics for the readout of the ATLAS liquid argon calorimeters

The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiation-tolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.

Overview of the high-level trigger electron and photon selection for the ATLAS experiment at the LHC

The 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 25 ns 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.

Implementation and performance of the seeded reconstruction for the ATLAS event filter

ATLAS is one of the four major Large Hadron Collider (LHC) experiments that will start data taking in 2007. It is designed to cover a wide range of physics topics. The ATLAS trigger system has to be able to reduce an initial 40 MHz event rate, corresponding to an average of 23 proton-proton inelastic interactions per every 25 ns bunch crossing, to 200 Hz admissible by the Data Acquisition System. The ATLAS trigger is divided in three different levels. The first one provides a signal describing an event signature using dedicated custom hardware. This signature must be confirmed by the High Level Trigger (HLT) which using commercial computing farms performs an event reconstruction by running a sequence of algorithms. The validity of a signature is checked after every algorithm execution. A main characteristic of the ATLAS HLT is that only the data in a certain window around the position flagged by the first level trigger are analyzed. In this work, the performance of one sequence that runs at the Event Filter level (third level) is demonstrated. The goal of this sequence is to reconstruct and identify high transverse momentum electrons by performing cluster reconstruction at the electromagnetic calorimeter, track reconstruction at the Inner Detector, and cluster track matching.

Implementation and Performance of the Seeded Reconstruction for the ATLAS Event Filter Selection Software

ATLAS 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 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 presentation, 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, were presented

Implementation and Performance of the High-Level Trigger electron and photon selection for the ATLAS experiment at the LHC

The 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 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). 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 ∗ S. Armstronga, A. dos Anjosb, J. T. M. Bainesc , C. P. Beed, , M. Bigliettie , J. A. Bogaertsf , V. Boisvertf , M. Bosmang , B. Caronh , P. Casadog , G. Cataldii , D. Cavallij , M. Cervettok , G. Comunel , P. Conde Muinof , A. De Santom , M. Diaz Gomezn, M. Dosilg , N. Ellisf , D. Emeliyanovc , B. Eppo, S. Falcianop , A. Farillaq , S. Georgem , V. Gheteo, S. Gonzalezr , M. Grothef , S. Kabanal , A. Khomichs, G. Kilvingtonm , N. Konstantinidist , A. Kootzu, A. Lowem, L. Luminarip, T. Maenof , J. Masikv , A. Di Mattiap , C. Meessend , A. G. Mellob , G. Merinog , R. Mooreh, P. Morettinik , A. Negriw , N. Nikitinx , A. Nisatip , C. Padillaf , N. Panikashviliy , F. Parodik , V. Perez Realel , J. L. Pinfoldh, P. Pintof , Z. Qiand, S. Resconij , S. Rosatif , C. Sanchezg , C. Santamarinaf , D. A. Scannicchiow , C. Schiavik , E. Segurag , J. M. de Seixasb , S. Sivoklokovx , R. Solukh, E. Stefanidist , S. Sushkovg , M. Suttont , S. Tapproggez , E. Thomasl, F. Touchardd, B. Venda Pintoaa, V. Vercesiw , P. Wernerf , S. Wheelerh,bb , F. J. Wickensc , W. Wiedenmannr , M. Wielerscc , G. Zobernigr aBrookhaven National Laboratory (BNL), Upton, New York, USA. bUniversidade Federal do Rio de Janeiro, COPPE/EE, Rio de Janeiro, Brazil. cRutherford Appleton Laboratory, Chilton, Didcot, UK. dCentre de Physique des Particules de Marseille, IN2P3-CNRS-Université d’Aix-Marseille 2, France eUniversity of Michigan, Ann Arbor, Michigan, USA. f CERN, Geneva, Switzerland. g Institut de Fı́sica d’Altes Energies (IFAE), Universidad Autónoma de Barcelona, Barcelona, Spain. hUniversity of Alberta, Edmonton, Canada. iDipartimento di Fisica dell’Università di Lecce e I.N.F.N., Lecce, Italy. jDipartimento di Fisica dell’Università di Milano e I.N.F.N., Milan, Italy. kDipartimento di Fisica dell’Università di Genova e I.N.F.N., Genova, Italy. lLaboratory for High Energy Physics, University of Bern, Switzerland. mDepartment of Physics, Royal Holloway, University of London, Egham, UK. nSection de Physique, Université de Genève, Switzerland. oInstitut für Experimentalphysik der Leopald-Franzens Universität, Innsbruck, Austria. pDipartimento di Fisica dell’Università di Roma “La Sapienza” e I.N.F.N., Rome, Italy. qDipartimento di Fisica dell’Università di Roma “Roma Tre” e I.N.F.N., Rome, Italy. rDepartment of Physics, University of Wisconsin, Madison, Wisconsin, USA. sLehrstuhl für Informatik V, Universität Mannheim, Mannheim, Germany. tDepartment of Physics and Astronomy, University College London, London, UK. uFachbereich Physik, Bergische Universitat Wuppertal, Germany. vInstitute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic. wDipartimento di Fisica Nucleare e Teorica dell’Università di Pavia e INFN, Pavia, Italy. xInstitute of Nuclear Physics, Moscow State University, Moscow, Russia. yDepartment of Physics, Technion, Haifa, Israel. zInstitut für Physik, Universität Mainz, Mainz, Germany. aaCFNUL Universidade de Lisboa, Faculdade de Ciências, Lisbon, Portugal.bbUniversity of California at Irvine, Irvine, USA. ccUniversity of Victoria, Victoria, Canada. 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.

Implementation and performance of the seeded reconstruction for the ATLAS event filter selection software

ATLAS 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 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 presentation, 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, were presented