Measuring supersymmetry Lafaye, R.; Plehn, T.; Rauch, M. ...
The European physical journal. C, Particles and fields,
2008, Letnik:
54, Številka:
4
Journal Article
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If new physics is found at the LHC (and the ILC) the reconstruction of the underlying theory should not be biased by assumptions about high-scale models. For the mapping of many measurements onto ...high-dimensional parameter spaces we introduce SFitter with its new weighted Markov chain technique. SFitter constructs an exclusive likelihood map, determines the best-fitting parameter point and produces a ranked list of the most likely parameter points. Using the example of the TeV-scale supersymmetric Lagrangian we show how a high-dimensional likelihood map will generally include degeneracies and strong correlations. SFitter allows us to study such model-parameter spaces employing Bayesian as well as frequentist constructions. We illustrate in detail how it should be possible to analyze high-dimensional new-physics parameter spaces like the TeV-scale MSSM at the LHC. A combination of LHC and ILC measurements might well be able to completely cover highly complex TeV-scale parameter spaces.
During summer and fall 2004, the response of a full slice of the ATLAS barrel detector to different particles was studied in controlled beam. One module of the ATLAS liquid argon barrel ...calorimeter—identical to the production modules and read out by the final front-end and back-end electronics—was used for electromagnetic calorimetry. This paper presents and discusses the electron performance of the LAr barrel calorimeter, including linearity, uniformity, and resolution with different amounts of material upstream the calorimeter and energies ranging from 1 to 250
GeV.
The time reconstruction performance of the ATLAS electromagnetic calorimeter readout is studied. The contribution of the electronics to the time resolution is estimated to be about 20
ps, thus ...demonstrating the possibility of achieving a small constant term in the time resolution for particles. The resolution to electromagnetic showers produced by an electron beam is also measured. After correction for the effects due to the calorimeter geometry, a 100
ps constant term is found for a typical cell.
The 2004 H8 Testbeam setup is used as a test ground of various aspects of the ATLAS detector. The H8 study program focuses on sub-detector and trigger system performance in combined and standalone ...mode, as well as offline reconstruction and analysis, but leaves also space for specialized studies and experimental setups. In a dedicated setup, a BIS type Monitored Drift Tube chamber was placed in front of the Liquid Argon Calorimeter and was attached to its support structure. The aim of this project is to perform positioning measurements of the Liquid Argon Calorimeter electrodes using the track information from the BIS muon chamber. Moreover, the goal is to study the performance of the chamber in positron and muon beams at different beam incident angles. Last but not least, we investigate the correlation between the position of the cluster barycenter in the Liquid Argon and the reconstructed track in the BIS chamber.
Higgs couplings can be affected by physics beyond the Standard Model. We study modifications through interactions with a hidden sector and in specific composite Higgs models accessible at the LHC. ...Both scenarios give rise to congruent patterns of universal, or partially universal, shifts. In addition, Higgs decays to the hidden sector may lead to invisible decay modes which we also exploit. Experimental bounds on such potential modifications will measure the concordance of an observed Higgs boson with the Standard Model.
Physics at the Large Hadron Collider (LHC) and the International
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Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and ...lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC/ILC Study Group so far is summarized in this report. Possible topics for future studies are outlined.
During the combined testbeam in summer 2004 a slice of the ATLAS barrel detector—including all detector sub systems from the inner tracker, the calorimetry to the muon system—was exposed to particle ...beams (electrons, pions, photons, muons) with different energies (1–350
GeV). The aim was to study the combined performance of the different detector sub systems in ATLAS-like conditions. We will present studies with different amounts of material in front of the calorimeter, representing various regions in the ATLAS detector, performance results from the electromagnetic calorimetry, including uniformity, resolution, and linearity as well as a discussion of the calibration scheme. The performance in the combined ATLAS-like set-up will be compared to the one obtained in stand-alone testbeams.
A high-granularity timing detector for the ATLAS phase-II upgrade Casado, M.P.; Adam Bourdarios, C.; Belfkir, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2022, Letnik:
1032
Journal Article
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The large increase of pileup interactions is one of the main experimental challenges for the HL-LHC physics programme. A powerful new way to mitigate the effects of pileup is to use high-precision ...timing information to distinguish between collisions occurring close in space but well-separated in time. A High-Granularity Timing Detector, based on low gain avalanche detector technology, is therefore proposed for the ATLAS Phase-II upgrade. Covering the pseudorapidity region between 2.4 and 4.0, this device will improve the detector physics performance in the forward region. The typical number of hits per track in the detector was optimized so that the target average time resolution per track for a minimum-ionising particle is 30 ps at the start of lifetime, increasing to 50 ps at the end of HL-LHC operation. The high-precision timing information improves the pileup reduction to improve the forward object reconstruction, complementing the capabilities of the upgraded Inner Tracker (ITk) in the forward regions of ATLAS and leading to an improved performance for both jet and lepton reconstruction. These improvements in object reconstruction performance translate into sensitivity gains and enhance the reach of the ATLAS physics programme at the HL-LHC. In addition, the HGTD offers unique capabilities for the online and offline luminosity determination, an important requirement for precision physics measurements.
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