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We discuss the physics potential and the experimental challenges of an upgraded LHC running at an instantaneous luminosity of 1035 cm-2s-1. The detector R&D needed to operate ATLAS and CMS in a very high radiation environment and the expected detector performance are discussed. A few examples of the increased physics potential are given, ranging from precise measurements within the Standard Model (in particular in the Higgs sector) to the discovery reach for several New Physics processes.
The response of pions and protons in the energy range of 20–180 GeV, produced at CERN's SPS H8 test-beam line in the ATLAS iron–scintillator Tile hadron calorimeter, has been measured. The test-beam configuration allowed the measurement of the longitudinal shower development for pions and protons up to 20 nuclear interaction lengths. It was found that pions penetrate deeper in the calorimeter than protons. However, protons induce showers that are wider laterally to the direction of the impinging particle. Including the measured total energy response, the pion-to-proton energy ratio and the resolution, all observations are consistent with a higher electromagnetic energy fraction in pion-induced showers. The data are compared with GEANT4 simulations using several hadronic physics lists. The measured longitudinal shower profiles are descr...
The Tile Calorimeter, which constitutes the central section of the ATLAS hadronic calorimeter, is a non-compensating sampling device made of iron and scintillating tiles. The construction phase of the calorimeter is nearly complete, and most of the effort now is directed toward the final assembly and commissioning in the underground experimental hall. The layout of the calorimeter and the tasks carried out during construction are described, first with a brief reminder of the requirements that drove the calorimeter design. During the last few years a comprehensive test-beam program has been followed in order to establish the calorimeter electromagnetic energy scale, to study its uniformity, and to compare real data to Monte Carlo simulation. The test-beam setup and first results from the data are described. During the test-beam period i...
The form factor of A(o)(b) baryons is estimated using 3.46 x 10(6) hadronic Z decays collected by the DELPM experiment between 1992 and 1995. Charmed A(c)(+) baryons fully reconstructed in the pK(-)pi(+), pK(o)(s), and Api(+)pi(+)pi(-) modes, are associated to a c S lepton with opposite charge in order to select A(o)(b) → A(c)(+)l(-)v(l) decays. From a combined likelihood and event rate fit to the b C distribution of the Isgur-Wise variable w, and using the Heavy Quark Effective Theory (HQET), the slope of the b-baryon form factor is measured to be p(2)=2.03+/-0.46(stat)(-1.00)(+0.72)(syst). The exclusive semileptonic branching fraction Br(A(b)(o) → A(c)(+)l(-)v(l)) can be derived from p(2) and is found to be (5.0(-0.8)(+1.1)(stat)(-1.2)(+1.6) (syst))%. Limits on other branching fractions are also obtained.
We report test beam studies of 11% of the production ATLAS Tile Calorimeter modules. The modules were equipped with production front-end electronics and all the calibration systems planned for the final detector. The studies used muon, electron and hadron beams ranging in energy from 3 to 350 GeV. Two independent studies showed that the light yield of the calorimeter was View the MathML source, exceeding the design goal by 40%. Electron beams provided a calibration of the modules at the electromagnetic energy scale. Over 200 calorimeter cells the variation of the response was 2.4%. The linearity with energy was also measured. Muon beams provided an intercalibration of the response of all calorimeter cells. The response to muons entering in the ATLAS projective geometry showed an RMS variation of 2.5% for 91 measurements over a range of...
A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20 to 350 GeV and beam impact points and angles corresponding to pseudorapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit.
A fully instrumented slice of the ATLAS central detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the response of the central calorimeters to pions with energies in the range between 3 and 9 GeV is presented. The linearity and the resolution of the combined calorimetry (electromagnetic and hadronic calorimeters) was measured and compared to the prediction of a detector simulation program using the toolkit Geant 4.
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