2,480 research outputs found

    The First Year at LHC: Diffractive Physics

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    At the LHC, diffractive physics will be explored by the dedicated experiment TOTEM whose Technical Design Report has been approved in Summer 2004. The experimental programme will be carried out partly in TOTEM standalone mode for purely forward phenomena like elastic scattering, and partly in collaboration with CMS for processes requiring a full rapidity coverage. ATLAS and ALICE are interested in diffraction for a later stage. This article presents the TOTEM/CMS running scenario for diffractive physics in the first year of LHC. We discuss which processes are within reach and with which statistics they can be measured.Comment: 11 pages, 7 figures; proceedings of "Physics at LHC", July 2004, Vienna; to be published in a supplement of the Czechoslovak Journal of Physic

    Optimierung der Operationsparameter von Hochdruckdriftrohren fuer ATLAS

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    TOTEM: Prospects for Total Cross-Section and Luminosity Measurements

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    With the installation of the T1 telescope and the Roman Pot stations at 147 m from IP5, the detector apparatus of the TOTEM experiment has been completed during the technical stop in winter 2010/2011. After the commissioning of the dedicated beam optics with beta* = 90 m, a first measurement of the total pp cross-section sigma_tot and -- simultaneously -- the luminosity L will be possible in the upcoming running season 2011. The precision envisaged is 3 % and 4 % for sigma_tot and L, respectively. An ultimate beam optics configuration with beta* ~ 1 km will later reduce the uncertainty to the 1 % level.Comment: 4 pages, 4 figures; presented at the LHC Lumi Days: LHC Workshop on LHC Luminosity Calibration, 13-14 January 2011, CERN, Geneva, Switzerland, pp. 7-1

    Estimation and analysis of the machine-induced background at the TOTEM roman pot detectors in the IR5 of the LHC

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    The problem of background generation in the experimental insertion IR5 of the LHC during machine operation in the dedicated TOTEM mode with low intensity beams and the specially designed β* = 1540 m optics is discussed. The sources of the machine-induced background in the IR5 forward physics areas are identified and their relative importance is evaluated. The results of the background simulation in the IR5 are presented, based on the most recent estimates of the residual gas density for TOTEM beam conditions. The methods for background analysis and rejection are explained

    Performance of the ATLAS Precision Muon Chambers under LHC Operating Conditions

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    For the muon spectrometer of the ATLAS detector at the large hadron collider (LHC), large drift chambers consisting of 6 to 8 layers of pressurized drift tubes are used for precision tracking covering an active area of 5000 m2 in the toroidal field of superconducting air core magnets. The chambers have to provide a spatial resolution of 41 microns with Ar:CO2 (93:7) gas mixture at an absolute pressure of 3 bar and gas gain of 2?104. The environment in which the chambers will be operated is characterized by high neutron and background with counting rates of up to 100 per square cm and second. The resolution and efficiency of a chamber from the serial production for ATLAS has been investigated in a 100 GeV muon beam at photon irradiation rates as expected during LHC operation. A silicon strip detector telescope was used as external reference in the beam. The spatial resolution of a chamber is degraded by 4 ?m at the highest background rate. The detection efficiency of the drift tubes is unchanged under irradiation. A tracking efficiency of 98% at the highest rates has been demonstrated
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