atlas detector cross section

As accelerators have grown, so too has the list of known particles that they might be used to investigate. Supersymmetry can potentially solve a number of problems in theoretical physics, such as the hierarchy problems within gauge theory, and is present in almost all models of string theory. [10][11][12] The second data-taking period, Run II, was completed at the end of 2018 with a recorded integrated luminosity of nearly 140/fb. It is similar in concept and function to the Pixel Detector but with long, narrow strips rather than small pixels, making coverage of a larger area practical. With much greater energy and greater collision rates, the LHC produces a tremendous number of top quarks, allowing ATLAS to make much more precise measurements of its mass and interactions with other particles. endobj The Transition Radiation Tracker (TRT), the outermost component of the inner detector, is a combination of a straw tracker and a transition radiation detector. The far-forward sections of the hadronic calorimeter are contained within the forward EM calorimeter's cryostat, and use liquid argon as well, while copper and tungsten are used as absorbers. This is intended to ensure that whatever form any new physical processes or particles might take, ATLAS will be able to detect them and measure their properties. This produces a total of 1 petabyte of raw data per second. [29] This high magnetic field allows even very energetic particles to curve enough for their momentum to be determined, and its nearly uniform direction and strength allow measurements to be made very precisely. fb •fid,SM=3.41±0.18fb •Differential cross sections as a function of 4ℓand jets •Good agreement is found between the data and the predictions of the SM. 29 0 obj [29] This magnetic field extends in an area 26 metres long and 20 metres in diameter, and it stores 1.6 gigajoules of energy. The detector operated with close to 100% efficiency and provided performance characteristics very close to its design values. cross section of the ATLAS detector, CERN's Large Hadron Collider. Created Date: 7/19/2018 1:59:20 PM Cross sections are measured separately for each final state in fiducial regions of high detector acceptance, as well as in the full phase space, over the mass region 66 - 116 GeV. The only established stable particles that cannot be detected directly are neutrinos; their presence is inferred by measuring a momentum imbalance among detected particles. Some hypotheses, based on the ADD model, involve large extra dimensions and predict that micro black holes could be formed by the LHC. endobj ATLAS was one of the two LHC experiments involved in the discovery of the Higgs boson in July 2012. The ATLAS experiment was proposed in its current form in 1994, and officially funded by the CERN member countries in 1995. [13] A second long shutdown (LS2) in 2019 and 2020 has followed, while ATLAS is being upgraded for Run III in 2021.[14]. ATLAS Detector and Physics Performance Technical Design Report. cross section with the ATLAS detector at LHC Biagio Di Micco∗ European Organization for Nuclear Research (CERN) E-mail:biagio.di.micco@cern.ch We present the measurement of the inclusive muon differential cross section (dσ/dpT) in pp collisions at √ s=7 TeV with the ATLAS detector. 16 0 obj endobj stream 414 WW candidates are observed, 232 WW signal and 170 backgrounds events are expected. The ATLAS Collaboration, the group of physicists who built and run the detector[clarification needed], was formed in 1992 when the proposed EAGLE (Experiment for Accurate Gamma, Lepton and Energy Measurements) and ASCOT (Apparatus with Super Conducting Toroids) collaborations merged their efforts to build a single, general-purpose particle detector for the Large Hadron Collider. Analysis of more properties of the particle and data collected in 2015 and 2016 confirmed this further. and Z/γ∗ production cross sections with the ATLAS detector ATLAS Collaboration CERN, 1211 Geneva 23, Switzerland Received: 12 December 2016 / Accepted: 11 May 2017 / Published online: 2 June 2017 © CERN for the benefit of the ATLAS collaboration 2017. The design was a combination of the two previous experiments, and also benefitted from the detector research and development that had been done for the Superconducting Super Collider. endobj [23] Its tremendous size is required to accurately measure the momentum of muons, which first go through all the other elements of the detector before reaching the muon spectrometer. Measurement of the Z →ττ andW →τν cross sections with the ATLAS detector Justin GRIFFITHS 1. 21 0 obj << /D (section*.13) /S /GoTo >> Due to this, many particle physicists believe it is possible that the Standard Model will break down at energies at the teraelectronvolt (TeV) scale or higher. The unfolded t differential cross section is … << /D (section*.4) /S /GoTo >> endobj (The role of each layer in the detector is discussed below.) It also serves the function of simply identifying muons – very few particles of other types are expected to pass through the calorimeters and subsequently leave signals in the Muon Spectrometer. << /D (section*.7) /S /GoTo >> endobj The ATLAS detector uses two large superconducting magnet systems to bend charged particles so that their momenta can be measured. It varies between 2 and 8 Teslameters. In March 2013, in the light of the updated ATLAS and CMS results, CERN announced that the new particle was indeed a Higgs boson. Cross sections are measured differentially in terms of Delta eta F, the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at eta = +/- 4.9, in which no final state particles are produced above a transverse momentum threshold p_T Cut. ATLAS (A Toroidal LHC ApparatuS)[1] is the largest, general-purpose particle detector experiment at the Large Hadron Collider (LHC), a particle accelerator at CERN (the European Organization for Nuclear Research) in Switzerland. The first cyclotron, an early type of particle accelerator, was built by Ernest O. Lawrence in 1931, with a radius of just a few centimetres and a particle energy of 1 megaelectronvolt (MeV). endobj Cross-sections are presented as a function of jet multiplicity and of the transverse momentum of the leading b-jet for … (6 Signal Acceptance and Background Estimate) These results are based on an integrated luminosity of 3:2 fb1collected in 2015 by the ATLAS detector at the LHC. The starting points of the tracks yield useful information for identifying particles; for example, if a group of tracks seem to originate from a point other than the original proton–proton collision, this may be a sign that the particles came from the decay of a hadron with a bottom quark (see b-tagging). The production cross-section for the process pp → ℓ+ℓ−γ + X (ℓ = e, μ) is measured within a fiducial phase-space region defined by kinematic requirements on the photon and the leptons, and by isolation requirements on the photon. The Tevatron and Large Electron–Positron Collider, were also designed for extremely tracking! Beam events on 10 September of that year physics will introduce additional violation... Are possible clues for new physical theories is supersymmetry of greater and greater mass with signals a. Surrounding the Inner detector Large superconducting magnet systems bend charged particles so that their momenta to be observed by.... 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