1,331 research outputs found

    The acceleration and storage of radioactive ions for a neutrino factory

    Full text link
    The term beta-beam has been coined for the production of a pure beam of electron neutrinos or their antiparticles through the decay of radioactive ions circulating in a storage ring. This concept requires radioactive ions to be accelerated to a Lorentz gamma of 150 for 6He and 60 for 18Ne. The neutrino source itself consists of a storage ring for this energy range, with long straight sections in line with the experiment(s). Such a decay ring does not exist at CERN today, nor does a high-intensity proton source for the production of the radioactive ions. Nevertheless, the existing CERN accelerator infrastructure could be used as this would still represent an important saving for a beta-beam facility. This paper outlines the first study, while some of the more speculative ideas will need further investigations.Comment: Accepted for publication in proceedings of Nufact02, London, 200

    ScotGrid: Providing an Effective Distributed Tier-2 in the LHC Era

    Get PDF
    ScotGrid is a distributed Tier-2 centre in the UK with sites in Durham, Edinburgh and Glasgow. ScotGrid has undergone a huge expansion in hardware in anticipation of the LHC and now provides more than 4MSI2K and 500TB to the LHC VOs. Scaling up to this level of provision has brought many challenges to the Tier-2 and we show in this paper how we have adopted new methods of organising the centres, from fabric management and monitoring to remote management of sites to management and operational procedures, to meet these challenges. We describe how we have coped with different operational models at the sites, where Glagsow and Durham sites are managed "in house" but resources at Edinburgh are managed as a central university resource. This required the adoption of a different fabric management model at Edinburgh and a special engagement with the cluster managers. Challenges arose from the different job models of local and grid submission that required special attention to resolve. We show how ScotGrid has successfully provided an infrastructure for ATLAS and LHCb Monte Carlo production. Special attention has been paid to ensuring that user analysis functions efficiently, which has required optimisation of local storage and networking to cope with the demands of user analysis. Finally, although these Tier-2 resources are pledged to the whole VO, we have established close links with our local physics user communities as being the best way to ensure that the Tier-2 functions effectively as a part of the LHC grid computing framework..Comment: Preprint for 17th International Conference on Computing in High Energy and Nuclear Physics, 7 pages, 1 figur

    Early expression of pregnancy-specific glycoprotein 22 (PSG22) by trophoblast cells modulates angiogenesis in mice.

    Get PDF
    Mouse and human pregnancy-specific glycoproteins (PSG) are known to exert immunomodulatory functions during pregnancy by inducing maternal leukocytes to secrete anti-inflammatory cytokines that promote a tolerogenic decidual microenvironment. Many such anti-inflammatory mediators also function as proangiogenic factors, which, along with the reported association of murine PSG with the uterine vasculature, suggest that PSG may contribute to the vascular adaptations necessary for successful implantation and placental development. We observed that PSG22 is strongly expressed around the embryonic crypt on Gestation Day 5.5, indicating that trophoblast giant cells are the main source of PSG22 during the early stages of pregnancy. PSG22 treatment up-regulated the secretion of transforming growth factor beta 1 and vascular endothelial growth factor A (VEGFA) in murine macrophages, uterine dendritic cells, and natural killer cells. A possible role of PSGs in uteroplacental angiogenesis is further supported by the finding that incubation of endothelial cells with PSG22 resulted in the formation of tubes in the presence and absence of VEGFA. We determined that PSG22, like human PSG1 and murine PSG17 and PSG23, binds to the heparan sulfate chains in syndecans. Therefore, our findings indicate that despite the independent evolution and expansion of human and rodent PSG, members in both families have conserved functions that include their ability to induce anti-inflammatory cytokines and proangiogenic factors as well as to induce the formation of capillary structures by endothelial cells. In summary, our results indicate that PSG22, the most abundant PSG expressed during mouse early pregnancy, is likely a major contributor to the establishment of a successful pregnancy.Fil: Blois, Sandra M.. University Medicine of Berlin; AlemaniaFil: Tirado González, Irene. University Medicine of Berlin; AlemaniaFil: Wu, Julie. Uniformed Services University of the Health Sciences; Estados UnidosFil: Barrientos, Gabriela Laura. University Medicine of Berlin; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Johnson, Briana. Uniformed Services University of the Health Sciences; Estados UnidosFil: Warren, James. Uniformed Services University of the Health Sciences; Estados UnidosFil: Freitag, Nancy. University Medicine of Berlin; AlemaniaFil: Klapp, Burghard F.. University Medicine of Berlin; AlemaniaFil: Irmak, Ster. University of Duisburg Essen; AlemaniaFil: Ergun, Suleyman. Julius Maximilians Universitat Wurzburg. Biozentrum; AlemaniaFil: Dveskler, Gabriela S.. Uniformed Services University of the Health Sciences; Estados Unido

    Differences in symptoms and cardiopulmonary responses to Treadmill versus Cycle cardiopulmonary exercise testing and comparison with the 6MWT in ILD

    Get PDF
    Aims: Cardiopulmonary exercise testing (CPET) is used for diagnostic and prognostic reasons in Interstitial Lung Disease (ILD). Our aims were to compare symptoms and cardiopulmonary responses between a) cycle and treadmill walking and b) between CPET and the 6MWT. Methods: 18 ILD patients (6 IPF; 12M), mean (SD) age 65.4 (12.6), FVC% pred. 72.7 (20.7), DLCO% pred. 42.2 (13.4) underwent CPET by cycle ergometry (C-CPET) and treadmill walking (T-CPET) in random order, with 30-45 min rest between tests, on a single session. On a second session 3-7 days apart, patients performed the 6MWT. Oxygen saturation (SpO2), heart rate (HR), breathlessness (BORG score) and leg fatigue/exertion (RPE scale) were recorded at rest, peak and at each minute of the 3-min recovery. We used the sign rank test with the null hypothesis of no difference between responses to the 3 tests of multiple CPET and symptom parameters. Results: Data were consistent with no differences between C-CPET and T-CPET in cardiopulmonary parameters (PeakVO2 p value=0.4, AT_VO2 p= 0.5, Peak VE/VCO2 p= 0.5, Peak VE/VO2 = 0.8). Desaturation (∆SpO2) was similar between T- CPET and C-CPET (p= 0.4) or 6MWT (0.7) but differed between C-CPET and 6MWT (p=0.03). The 3-minute SpO2 recovery was slower in T-CPET than the other tests. Change in HR (∆HR) and 3-min recovery was similar between CPET modes (p=0.1) but statistically lower in the 6MWT (p= 0.001). Breathlessness was greater in T-CPET than C-CPET (∆BORG p= 0.04) and recovery slower than the other two tests. Patients with CTD-ILD reported a preference for T-CPET. Summary/Conclusions: Cardiopulmonary parameters can be derived accurately from both types of CPET. The drop in oxygen saturation at the 6MWT was similar to that of the maximal T-CPET so, it can be used in ILD patients to estimate level of desaturation, even though the 6MWT underestimates the delay in SpO2 recovery. Funding source: This abstract presents independent research funded by the National Institute for Health Research (NIHR) under its Research for Patient Benefit (RfPB) Programme (Grant Reference Number PB-PG-1112-29067). The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health, UK

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

    Get PDF
    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Standalone vertex finding in the ATLAS muon spectrometer

    Get PDF
    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

    Get PDF
    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

    Get PDF
    A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

    Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

    Get PDF
    A measurement of the production cross-section for top quark pairs(\ttbar) in pppp collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron ee or muon μ\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, μμ\mu\mu or eμe\mu) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be 12.2±3.912.2 \pm 3.9 events and 2.5±0.62.5 \pm 0.6 events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

    Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

    Get PDF
    The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30
    corecore