74 research outputs found

    The NOMAD experiment at the CERN SPS

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    The NOMAD experiment is a short base-line search for ΜΌ→Μτ\nu_{\mu}\rightarrow \nu_{\tau} oscillations in the CERN neutrino beam. The Μτ\nu_{\tau}'s are searched for through their charged-current interactions followed by the observation of the resulting τ−\tau^{-} through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors, and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction of individual particles is demonstrated through the ability of NOMAD to observe Ks0^0_{\rm s}'s, Λ0\Lambda^0's and π0\pi^0's. Finally, the observation of τ−\tau^{-} through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed

    Familial hypercholesterolaemia in children and adolescents from 48 countries: a cross-sectional study

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    Background: Approximately 450 000 children are born with familial hypercholesterolaemia worldwide every year, yet only 2·1% of adults with familial hypercholesterolaemia were diagnosed before age 18 years via current diagnostic approaches, which are derived from observations in adults. We aimed to characterise children and adolescents with heterozygous familial hypercholesterolaemia (HeFH) and understand current approaches to the identification and management of familial hypercholesterolaemia to inform future public health strategies. Methods: For this cross-sectional study, we assessed children and adolescents younger than 18 years with a clinical or genetic diagnosis of HeFH at the time of entry into the Familial Hypercholesterolaemia Studies Collaboration (FHSC) registry between Oct 1, 2015, and Jan 31, 2021. Data in the registry were collected from 55 regional or national registries in 48 countries. Diagnoses relying on self-reported history of familial hypercholesterolaemia and suspected secondary hypercholesterolaemia were excluded from the registry; people with untreated LDL cholesterol (LDL-C) of at least 13·0 mmol/L were excluded from this study. Data were assessed overall and by WHO region, World Bank country income status, age, diagnostic criteria, and index-case status. The main outcome of this study was to assess current identification and management of children and adolescents with familial hypercholesterolaemia. Findings: Of 63 093 individuals in the FHSC registry, 11 848 (18·8%) were children or adolescents younger than 18 years with HeFH and were included in this study; 5756 (50·2%) of 11 476 included individuals were female and 5720 (49·8%) were male. Sex data were missing for 372 (3·1%) of 11 848 individuals. Median age at registry entry was 9·6 years (IQR 5·8-13·2). 10 099 (89·9%) of 11 235 included individuals had a final genetically confirmed diagnosis of familial hypercholesterolaemia and 1136 (10·1%) had a clinical diagnosis. Genetically confirmed diagnosis data or clinical diagnosis data were missing for 613 (5·2%) of 11 848 individuals. Genetic diagnosis was more common in children and adolescents from high-income countries (9427 [92·4%] of 10 202) than in children and adolescents from non-high-income countries (199 [48·0%] of 415). 3414 (31·6%) of 10 804 children or adolescents were index cases. Familial-hypercholesterolaemia-related physical signs, cardiovascular risk factors, and cardiovascular disease were uncommon, but were more common in non-high-income countries. 7557 (72·4%) of 10 428 included children or adolescents were not taking lipid-lowering medication (LLM) and had a median LDL-C of 5·00 mmol/L (IQR 4·05-6·08). Compared with genetic diagnosis, the use of unadapted clinical criteria intended for use in adults and reliant on more extreme phenotypes could result in 50-75% of children and adolescents with familial hypercholesterolaemia not being identified. Interpretation: Clinical characteristics observed in adults with familial hypercholesterolaemia are uncommon in children and adolescents with familial hypercholesterolaemia, hence detection in this age group relies on measurement of LDL-C and genetic confirmation. Where genetic testing is unavailable, increased availability and use of LDL-C measurements in the first few years of life could help reduce the current gap between prevalence and detection, enabling increased use of combination LLM to reach recommended LDL-C targets early in life

    Search for ΜΌ→Μe\nu\mu \to \nu_{e} Oscillations in the NOMAD Experiment

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    We present the results of a search for nu(mu)-->nu(e) oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of nu(e) in a predominantly nu(mu) wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are delta m^2 10 eV^2

    Study of D∗+D^{*+} production in ΜΌ\nu_{\mu} charged current interactions in the NOMAD experiment

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    A search was made among ΜΌ\nu_\mu charged current events collected in the NOMAD experiment for the reaction: ΜΌ+N→Ό−+D⋆++hadronsâ†ȘD0+π+â†ȘK−+π+A\nu_\mu + N \rightarrow \mu^- + D^{\star+} + hadrons \hookrightarrow D^0 + \pi^+ \hookrightarrow K^- + \pi^+ A D^{\star+}samplecomposedof47events,with90 sample composed of 47 events, with 90% purity, was extracted. The D^{\star+}yieldin yield in \nu_\muchargedcurrentinteractionswasmeasuredtobe charged current interactions was measured to be T = (0.99 \pm 0.15(stat.) \pm 0.11(syst.))%. The mean fraction of the hadronic jet energy taken by the D^{\star+}is is 0.67 \pm 0.02(stat) \pm 0.02(syst.).Thedistributionsofthefragmentationvariables. The distributions of the fragmentation variables z,, {P_{T}}^2and and x_Ffor for D^{\star+}$ are also presented

    Precision Measurement of Scaled Momentum, Charge Multiplicity and Thrust in ΜΌN\nu_{\mu}N and Μ‟ΌN\overline\nu_{\mu}N Interactions

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    We report the first precision measurements of the scaledmomentum, the charge multiplicity, and the thrust of hadronic jets inthe Breit frame in Deep Inelastic Scattering \nun\ and\nunbar\ charged current events over the Q2Q^2 range from 1 to 100 \GeVsq\ . Theneutrino data, obtained in the NOMAD experiment at the CERN SPS, extend the Q2Q^2-evolution ofthese parametersby two orders of magnitude, and with commensurate precision, whencompared to those reported by the \ep\ and \ee\ experiments

    Coherent J/psi photoproduction at forward rapidity in ultra-peripheral Pb-Pb collisions at root s(NN)=5.02 TeV

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    The ALICE collaboration performed the first rapidity-differential measurement of J/psi coherent photoproduction in ultra-peripheral Pb\u2013Pb collisions at a center-of-mass energy sqrt(sNN) = 5.02 TeV. The J/psi is detected via its dimuon decay in the forward rapidity region (-4.0 < y < -2.5) for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 \u3bcb 121. The cross section for J/psi coherent production is presented in six rapidity bins. The results are compared with theoretical models for J/psi coherent photoproduction. These comparisons indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of psi' to J/psi coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons
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