218 research outputs found
Performance of the ATLAS Inner Detector Trigger Algorithms in p-p collisions at sqrt(s)=900 GeV and sqrt(s)=7 TeV
No full textThe ATLAS Inner Detector trigger algorithms were running online during data taking with proton-proton collisions at the Large Hadron Collider (LHC) in December 2009 and spring 2010. We will present preliminary results on the performance of the algorithms in collisions at centre-of-mass energies of 900GeV and 7 TeV, including comparisons to the ATLAS offline tracking algorithms and to simulations. The ATLAS trigger performs the online event selection in three stages. The Inner Detector information is used in the second and third triggering stages, called Level-2 trigger (L2) and Event Filter (EF) respectively, and collectively the High Level Triggers (HLT). The HLT runs software algorithms in a large farm of commercial CPUs and is designed to reject collision events in real time, keeping the most interesting few in every thousand. The average execution time per event at L2(/EF) is about 40ms(/4s) and the Inner Detector trigger algorithms can take only a fraction of that. Within this time, the data from interesting regions of the Inner Detector have to be accessed from central buffers through the network, unpacked, clustered and converted to the ATLAS global coordinates, then pattern recognition follows to identify the trajectories of charged particles (tracks), and finally these tracks are used in combination with other information to accept or reject events, according to whether they satisfy one or more trigger signatures. We w ill show results from the commissioning of the HLT track reconstruction for identifying various event signatures and the performance of the Inner Detetector trigger algorithms in this context. Also the application of the L2 tracks for the online determination of the LHC beam position will be presented
Charm and beauty reconstruction in ATLAS
No full textThe article describes the selection of samples of charm and beauty mesons, exclusively or semi-exclusively reconstructed on data collected in 2010. These samples have been used to calibrate the flavour tagging algorithms (through the selection of pure, or heavily enriched, b-jets samples) and for measurements of direct physical interest (b-hadrons production cross section)
Open Charm and Bottom in ATLAS
No full textTalk to be presentend at the "First ReteQuarkonii Workshop", Nantes 25-28 October 201
Measurement of the beauty production cross section and flavour tagging calibration with the ATLAS detector at the LHC
No full textThe beauty quark is one of the fundamental particles of the SM, and is expected to play a crucial role in the ATLAS physics program.In particular the production rate of beauty quark at LHC energies is an important test of the QCD predictions. Furthermore, the identification of jets originating from -quark hadronisation (-tagging) is crucial for many ATLAS physics investigations, like the search for the SM Higgs Boson in the decay. The work presented in this thesis makes use of the reconstruction of two physics signals, mesons, selected through the fully hadronic decay , and correlations. The -hadron production cross section is measured in collisions at \sqrt{s}=7\TeV, using 3.3\,\mbox{pb}^{-1} of integrated luminosity, collected during the 2010 LHC run. The -hadrons are selected by partially reconstructing final states. Differential cross sections are measured as functions of the transverse momentum and pseudorapidity. The measured production cross section for a -hadron with GeV and is 32.7 \pm 0.8 (\mbox{stat.}) ^{+4.5}_{-6.8} (\mbox{syst.}) \,\,\mu\mbox{b}, higher than the next-to-leading-order QCD predictions but consistent within the experimental and theoretical uncertainties. This thesis presents also two innovative methods, based on the and samples reconstructed inside jets, to calibrate on data the -tagging efficiency respectively on -jets and -jets. This is a fundamental requirement to use -tagging in ATLAS physics analyses. A sample of correlations reconstructed inside jets allows to reconstruct a very pure sample of -jets, very suitable to be used to calibrate the -jet tagging efficiency on data. This has been used with 2010 data, showing similar performance to the already established methods, and thus proving to be an excellent complementary technique to other standard calibration methods. No calibrations have been ever developed to measure -jet tagging efficiency. During this thesis, a method suited to perform this task has been developed. It is based on the selection of a sample of mesons reconstructed inside jets, which allows to collect a sample of -jets with high purity. This method provided the first -jet tagging calibration in ATLAS and its results have been used to correct the simulations of all physics analyses, implying -tagging, performed with 2011 and 2012 data samples
Assessing soil carbon dioxide and methane fluxes from a Scots pine raised bog-edge-woodland
No full textAcknowledgements: We thank the James Hutton Institute Aberdeen for providing laboratory and transport facilities, especially Richard Hewison, who completed the vegetation survey of the site and Graham Gaskin and Alison Wilkinson for providing assistance with field equipment. Author J Yeluripati was supported by the Scottish Government’s Strategic Research Programme (2016–2021): Research Deliverable 1.1.3: Soils and Greenhouse Gas Emissions. I also thank William Jessop (York University), who provided peat depth measurements and my dearest friends Anna Ferretto, Luka Paradiz Udovc, Douglas Wardell-Johnson, Ben Butler, Lucho Quinzo and Ben M. Taylor for offering their invaluable help with field measurements. We lastly thank Toni Clarcke for helping with statistical analysis and Michael Bell (Forest Research) for improvements to the manuscript. Funding: This research was funded by Scottish Forestry and the University of Aberdeen.Peer reviewe
Influence of thermomechanical treatment on the shape memory effect and pseudoelasticity behavior of conventional and additive manufactured Fe–Mn–Si–Cr–Ni-(V,C) shape memory alloys
No full textThis study evaluated the influence of heat treatment and thermomechanical training on the microstructural evolution and mechanical characteristics of conventional and additive-manufactured FeMnSi-based shape memory alloys. The conventional samples were produced by casting and rolling. The additive-manufactured samples were manu-factured using the laser powder bed fusion (L-PBF) technique. Both specimens were sub-jected to the same heat treatment and thermomechanical training. The heat treatment involved solution annealing at 1050 & DEG;C for 2 h and aging at 750 & DEG;C for 6 h, and the ther-momechanical training concluded with a 4% elongation at ambient temperature followed by annealing at 250 & DEG;C for 15 min. This training cycle was repeated four times for each sample after heat treatment. The heat treatment improved the pseudoelasticity and shape memory effect of the samples. Although training further enhanced the pseudoelasticity, it also reduced the shape memory effect. Thermomechanical training led to the formation of a large number of stacking faults, which facilitated the inverse phase transformation of martensite (& epsilon;) to austenite (g) during unloading, resulting in improved pseudoelasticity. The heat-treated additive-manufactured samples showed the highest total recovery strain owing to the pseudoelasticity and shape memory effect. This characteristic could be due to the smaller grain size and higher volume fraction of precipitates. The precipitates and grain refinement improved the conditions for partial dislocation motion by increasing the back stresses on the martensite tip. & COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Adverse reactions and complications caused by hyaluronic acid facial injections: a scoping review protocol
No full textThe use of hyaluronic acid (HA) dermal fillers has gained increasing popularity in facial harmonization due to their biocompatibility, safety, and efficacy. However, as the number of procedures rises, reports of complications and adverse reactions have also increased, ranging from mild to severe cases. This scoping review aims to map the existing literature on adverse reactions and complications associated with the use of HA facial fillers. Randomized clinical trials, cross-sectional studies, retrospective or prospective cohort studies, case series, or case reports that evaluate or report the use of hyaluronic acid for facial filling in healthy adult patients (over 18 years old) and document any type of adverse reaction or complication will be included. Searches will be conducted in PubMed, Scopus, and Web of Science databases. Study selection will be carried out independently by two researchers, with each extracting data from half of the included studies. The following data will be collected: author name, publication year, study design, objectives, population/sample, hyaluronic acid rheology (categorized as low, medium, or high), key findings related to complications and adverse reactions, and study conclusions. Initially, a descriptive analysis of the data will be performed, considering the different study designs and reported complications
Search for dark matter candidates and large extra dimensions in events with a jet and missing transverse momentum with the ATLAS detector
No full textOpen Access, Copyright CERN, for the benefit of the ATLAS collaboration. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited
Search for dark matter produced in association with a hadronically decaying vector boson in pp collisions at =13 TeV with the ATLAS detector
No full textSee paper for full list of authors - 10 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to PLB, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/EXOT-2015-08/International audienceA search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 /fb of pp collisions at =13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a W or Z boson and with large missing transverse momentum are analysed. The data are consistent with the Standard Model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter
Search for supersymmetry in events containing a same-flavour opposite-sign dilepton pair, jets, and large missing transverse momentum in TeV collisions with the ATLAS detector
No full textSee paper for full list of authors – 44 pages plus author list (61 pages total), 13 figures, 18 tables, submitted to Eur. Phys. J. C, all figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/SUSY-2014-10/International audienceTwo searches for supersymmetric particles in final states containing a same-flavour opposite-sign lepton pair, jets and large missing transverse momentum are presented. The proton-proton collision data used in these searches were collected at a centre-of-mass energy TeV by the ATLAS detector at the Large Hadron Collider and corresponds to an integrated luminosity of 20.3 fb. Two leptonic production mechanisms are considered: decays of squarks and gluinos with bosons in the final state, resulting in a peak in the dilepton invariant mass distribution around the -boson mass; and decays of neutralinos (e.g. ), resulting in a kinematic endpoint in the dilepton invariant mass distribution. For the former, an excess of events above the expected Standard Model background is observed, with a significance of 3 standard deviations. In the latter case, the data are well-described by the expected Standard Model background. The results from each channel are interpreted in the context of several supersymmetric models involving the production of squarks and gluinos
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