The overall dimensions of the ATLAS experiment and its harsh environment, due to radiation and magnetic field, represent new challenges for the implementation of the detector control system (DCS). It ...supervises all hardware of the ATLAS detector, monitors the infrastructure of the experiment, and provides information exchange with the LHC accelerator. The system must allow for the operation of the different ATLAS subdetectors in stand-alone mode, as required for calibration and debugging, as well as the coherent and integrated operation of all subdetectors for physics datataking. For this reason, the detector control system is logically arranged to map the hierarchical organization of the ATLAS detector. Special requirements are placed onto the ATLAS detector control system because of the large number of distributed I/O channels and of the inaccessibility of the equipment during operation. Standardization is a crucial issue for the design and implementation of the control system because of the large variety of equipment and the high number of different groups involved working all around the world. The functions of the two main components of the DCS, namely the distributed back-end software system, which will be based on a commercial SCADA package, and the subdetector's front-end systems, with extensive use of the CAN fieldbus, are explained. The standard readout chain of the DCS, which comprises both back-end software and general-purpose front-end equipment, is described and its performance is discussed.
ATLAS DAQ/HLT rack DCS Ermoline, Yuri; Burckhart, Helfried; Francis, David ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2007, Letnik:
572, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The ATLAS Detector Control System (DCS) group provides a set of standard tools, used by subsystems to implement their local control systems. The ATLAS Data Acquisition and High Level Trigger ...(DAQ/HLT) rack DCS provides monitoring of the environmental parameters (air temperatures, humidity, etc.). The DAQ/HLT racks are located in the underground counting room (20 racks) and in the surface building (100 racks). The rack DCS is based on standard ATLAS tools and integrated into overall operation of the experiment. The implementation is based on the commercial control package and additional components, developed by CERN Joint Controls Project Framework. The prototype implementation and measurements are presented.
ATLAS Status and First Run Scenarios for B Physics Burckhart, H.J.; Eerola, P.
11th International Conference on B-Physics at Hadron Machines,Oxford, United Kingdom,2006-09-25 - 2006-09-29,
08/2007, Letnik:
170
Journal Article, Conference Proceeding
This article summarizes the status of the ATLAS detector and its commissioning as of autumn 2006, one year before the expected LHC start-up. The initial running scenarios and goals for
B physics are ...presented for the foreseen pilot run with 900 GeV centre-of-mass energy in autumn 2007, as well as for the first physics run in 2008 at the nominal centre-of-mass energy of 14 TeV.
ATLAS is one of the four large experiments at the Large Hadron Collider at CERN. The detector itself and the surrounding structures in the cavern of the experiment are accessible for people during ...maintenance periods. People can easily be isolated and difficult to localize in which case their safety may be compromised in this very complex environment. Therefore a dedicated system called ¿Finding Persons Inside ATLAS Areas¿ has been designed and implemented to track persons in the experimental cavern. It is based on a network of passive infrared sensors which are read out by specific front-end electronics. A complex software architecture provides active tracking of people in the cavern with the possibility to detect abnormal situations where people are possibly in danger. This paper describes the technological choices which have been made for this monitoring system and explains the implementation of the software components. This provides a tool for the operation in the control room of ATLAS to actively follow people in the cavern underground. As the system is data-driven, it can be easily adapted to other environments where similar safety problems exist.
Cross-sections and angular distributions for hadronic and lepton-pair final states in e + e- collisions at centre-of-mass energies between 189 GeV and 209 GeV, measured with the OPAL detector at LEP, ...are presented and compared with the predictions of the Standard Model. The measurements are used to determine the electromagnetic coupling constant \(\alpha_{\mathrm{em}}\) at LEP 2 energies. In addition, the results are used together with OPAL measurements at 91-183 GeV within the S-matrix formalism to determine the \(\gamma\)-Z interference term and to make an almost model-independent measurement of the Z mass. Limits on extensions to the Standard Model described by effective four-fermion contact interactions or the addition of a heavy Z’ boson are also presented.
Hadronic event shape distributions from e super(+)e super(-) annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 GeV are used to determine the strong ...coupling alpha sub(S). The results are based on QCD predictions complete to the next-to-next-to-leading order (NNLO), and on NNLO calculations matched to the resummed next-to-leading-log-approximation terms (NNLO+NLLA). The combined NNLO result from all variables and centre-of-mass energies is while the combined NNLO+NLLA result is The completeness of the NNLO and NNLO+NLLA results with respect to missing higher order contributions, studied by varying the renormalization scale, is improved compared to previous results based on NLO or NLO+NLLA predictions only. The observed energy dependence of alpha sub(S) agrees with the QCD prediction of asymptotic freedom and excludes the absence of running.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This report summarizes the final results from the OPAL collaboration on searches for neutral Higgs bosons predicted by the Minimal Supersymmetric Standard Model (MSSM). CP-conserving and, for the ...first time at LEP, CP-violating scenarios are studied. New scenarios are also included, which aim to set the stage for Higgs searches at future colliders. The results are based on the data collected with the OPAL detector at e + e- centre-of-mass energies up to 209 GeV. The data are consistent with the prediction of the Standard Model with no Higgs boson produced. Model-independent limits are derived for the cross-sections of a number of event topologies motivated by predictions of the MSSM. Limits on Higgs boson masses and other MSSM parameters are obtained for a number of representative MSSM benchmark scenarios. For example, in the CP-conserving scenario mh-max where the MSSM parameters are adjusted to predict the largest range of values for mh at each \(\tan\beta\), and for a top quark mass of 174.3 GeV, the domain \(0.7 < \tan\beta < 1.9\) is excluded at the 95% confidence level and Higgs boson mass limits of mh > 84.5 GeV and mA > 85.0 GeV are obtained. For the CP-violating benchmark scenario CPX which, by construction, enhances the CP-violating effects in the Higgs sector, the domain \(\tan\beta < 2.8\) is excluded but no universal limit can be set on the Higgs boson masses.
PDF
