Search results for " Collider"
showing 10 items of 1415 documents
Measurement of light-by-light scattering and search for axion-like particles with 2.2 nb−1 of Pb+Pb data with the ATLAS detector
2021
We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; ANID, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF and DNSRC, Denmark; IN2P3-CNRS and CEA-DRF/IRFU, France; SRNSFG, Georgia; BMBF, HGF and MPG, Germany; GSRT, Greece; RGC and Hong Kong SAR, China; ISF and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Mor…
Comparison between simulated and observed LHC beam backgrounds in the ATLAS experiment at E beam =4 TeV
2018
Results of dedicated Monte Carlo simulations of beam-induced background (BIB) in the ATLAS experiment at the Large Hadron Collider (LHC) are presented and compared with data recorded in 2012. During normal physics operation this background arises mainly from scattering of the 4 TeV protons on residual gas in the beam pipe. Methods of reconstructing the BIB signals in the ATLAS detector, developed and implemented in the simulation chain based on the FLUKA Monte Carlo simulation package, are described. The interaction rates are determined from the residual gas pressure distribution in the LHC ring in order to set an absolute scale on the predicted rates of BIB so that they can be compared qua…
Search for weakly decaying b -flavored pentaquarks
2018
Investigations of the existence of pentaquark states containing a single $b$ (anti)quark decaying weakly into four specific final states J/$\psi K^+\pi^- p$, J/$\psi K^- \pi^- p$, J/$\psi K^- \pi^+ p$, and $J/\psi \phi (1020) p$ are reported. The data sample corresponds to an integrated luminosity of 3.0/fb in 7 and 8 TeV pp collisions acquired with the LHCb detector. Signals are not observed and upper limits are set on the product of the production cross section times branching fraction with respect to that of the $\Lambda_b$.
Searches for lepton number violating $K^+$ decays
2019
The NA62 experiment at CERN reports a search for the lepton number violating decays K+ -> pi(-)e(+)e(+) and K+ -> pi(-)mu(+)mu(+) using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of 2.2 x 10(-10) and 4.2 x 10(-11) are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively.
A new ATLAS muon CSC readout system with system on chip technology on ATCA platform
2015
The ATLAS muon Cathode Strip Chamber (CSC) backend readout system has been upgraded during the LHC 2013-2015 shutdown to be able to handle the higher Level-1 trigger rate of 100 kHz and the higher occupancy at Run 2 luminosity. The readout design is based on the Reconfigurable Cluster Element (RCE) concept for high bandwidth generic DAQ implemented on the Advanced Telecommunication Computing Architecture (ATCA) platform. The RCE design is based on the new System on Chip XILINX ZYNQ series with a processor-centric architecture with ARM processor embedded in FPGA fabric and high speed I/O resources together with auxiliary memories to form a versatile DAQ building block that can host applicati…
Real-time data processing in the ALICE High Level Trigger at the LHC
2019
At the Large Hadron Collider at CERN in Geneva, Switzerland, atomic nuclei are collided at ultra-relativistic energies. Many final-state particles are produced in each collision and their properties are measured by the ALICE detector. The detector signals induced by the produced particles are digitized leading to data rates that are in excess of 48 GB/$s$. The ALICE High Level Trigger (HLT) system pioneered the use of FPGA- and GPU-based algorithms to reconstruct charged-particle trajectories and reduce the data size in real time. The results of the reconstruction of the collision events, available online, are used for high level data quality and detector-performance monitoring and real-tim…
Measurements of the top quark branching ratios into channels with leptons and quarks with the ATLAS detector
2015
Measurements of the branching ratios of top quark decays into leptons and jets using events with t[bar over t] (top antitop) pairs are reported. Events were recorded with the ATLAS detector at the LHC in pp collisions at a center-of-mass energy of 7 TeV. The collected data sample corresponds to an integrated luminosity of 4.6 fb[superscript −1]. The measured top quark branching ratios agree with the Standard Model predictions within the measurement uncertainties of a few percent.
Performance of $b$-Jet Identification in the ATLAS Experiment
2016
We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF, DNSRC and Lundbeck Foundation, Denmark; IN2P3-CNRS, CEA-DSM/IRFU, France; GNSF, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT an…
Search for Magnetic Monopoles and Stable High-Electric-Charge Objects in 13 Tev Proton-Proton Collisions with the ATLAS Detector
2020
We thank CERN for the very successful operation of the LHC, aswell as the support staff fromour institutionswithout whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; FWF, BMWFW, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq, FAPESP, Brazil; NSERC, CFI, NRC, Canada; CERN; CONICYT, Chile; CAS, NSFC, MOST, China; COLCIENCIAS, Colombia; VSC CR, MSMT CR, MPO CR, Czech Republic; DNSRC, DNRF, Denmark; IN2P3-CNRS, CEA-DRF/IRFU, France; SRNSFG, Georgia; MPG, HGF, BMBF, Germany; GSRT, Greece; RGC, Hong Kong SAR, Hong Kong China; Benoziyo Center, ISF, Israel; INFN, Italy; JSPS, MEXT, Japan; JINR; CNRST, Morocco; NWO, Nether…
Measurement of the SMC muon beam polarisation using the asymmetry in the elastic scattering off polarised electrons
2000
A muon beam polarimeter was built for the SMC experiment at the CERN SPS, for beam energies of 100 and 190 GeV. The beam polarisation is determined from the asymmetry in the elastic scattering off the polarised electrons of a ferromagnetic target whose magnetisation is periodically reversed. At muon energies of 100 and 190 GeV the measured polarisation is P-mu = -0.80 +/- 0.03 (stat.) +/- 0.02 (syst.) and P-mu = - 0.797 +/- 0.011 (stat.) +/- 0.012 (syst.), respectively. These results agree with measurements of the beam polarisation using a shape analysis of the decay positron energy spectrum. (C) 2000 Elsevier Science B.V. All rights reserved.