289 research outputs found

    Comparison of 120Sn(6He,6He)120Sn and 120Sn(alpha,alpha)120Sn elastic scattering and signatures of the 6He neutron halo in the optical potential

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    Cross sections of 120^{120}Sn(α\alpha,α\alpha)120^{120}Sn elastic scattering have been extracted from the α\alpha particle beam contamination of a recent 120^{120}Sn(6^6He,6^6He)120^{120}Sn experiment. Both reactions are analyzed using systematic double folding potentials in the real part and smoothly varying Woods-Saxon potentials in the imaginary part. The potential extracted from the 120^{120}Sn(6^6He,6^6He)120^{120}Sn data may be used as the basis for the construction of a simple global 6^6He optical potential. The comparison of the 6^6He and α\alpha data shows that the halo nature of the 6^6He nucleus leads to a clear signature in the reflexion coefficients ηL\eta_L: the relevant angular momenta LL with ηL≫0\eta_L \gg 0 and ηLâ‰Ș1\eta_L \ll 1 are shifted to larger LL with a broader distribution. This signature is not present in the α\alpha scattering data and can thus be used as a new criterion for the definition of a halo nucleus.Comment: 13 pages, 7 figures, accepted for publication in Phys. Rev.

    α-particle production in 6He + 120Sn collisions

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    The collision 6He+120Sn has been investigated at four energies near the Coulomb barrier. A large yield of α particles has been detected, with energies around the energy of the scattered 6He beam. The energy and angular distributions of the α particles have been analyzed and compared with breakup and neutron transfer calculations.Ministerio de Ciencia e Innovación (España) FPA2006-13807-c02-01Junta de Andalucía P07-FQM-02894Ministerio de Educación y Ciencia (España) PCI2006-A7-0654Programa Consolider-Ingenio 2010 (España) CSD2007-0004

    Experimental study of He6+Be9 elastic scattering at low energies

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    New data for the He6+Be9 reaction at Elab=16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction. © 2011 American Physical Society.This work has been partially supported by the Spanish Ministerio de Ciencia e InnovacionŽ under Projects FPA2009-07653 and PCI2006-A7-0654 and by the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042).Peer Reviewe

    ValidaciĂłn del Nursing Activities Score en unidades de cuidados intensivos portuguesas

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    Objective: to describe the process of adaptation and validation of the Nursing Activities Score to the Portuguese context. Method: this was a pilot study of adaptation and validation of the Nursing Activities Score with a sample consisting of 67 patients hospitalized in the intensive care units of three Portuguese hospitals. The construct validity was assessed through factor analysis procedures and the internal consistency of the items was measured through the Cronbach’s alpha coeffi cient. Results: a mean workload value of 63.04% (SD = 14.25; Median = 61.30) was obtained. Psychometric data revealed a Cronbach’s alpha of 0.71 in the total scale, indicating an acceptable accuracy. Confi rmatory factor analysis suggested an appropriate adjustment between the model and the data (χ2 (199) = 214.5, p = 0.214; CFI = 0.95; RMSA = 0.035). Conclusion: in the present study, the Portuguese version of the Nursing Activities Score was found to be a valid instrument, enabling a safe assessment of the workload of nurses.Objetivo: descrever o processo de adaptação e validação do Nursing Activities Score para o contexto portuguĂȘs. MĂ©todo: trata-se de um estudo-piloto de adaptação e validação do Nursing Activities Score, com amostra de 67 doentes internados em unidades de cuidados intensivos de trĂȘs hospitais portugueses. A validade de constructo avaliou-se mediante procedimentos de anĂĄlise fatorial e a consistĂȘncia interna dos itens atravĂ©s do coefi ciente Alpha de Cronbach. Resultados: obteve-se um valor mĂ©dio da carga de trabalho de 63,04% (DP = 14,25; Mediana = 61,30). Os dados psicomĂ©tricos revelaram um Alpha de Cronbach de 0,71, na escala total, indicando uma fi delidade aceitĂĄvel. A anĂĄlise fatorial confi rmatĂłria sugeriu um ajustamento adequado entre o modelo e os dados (χ2(199) = 214,5, p = 0,214; CFI = 0,95; RMSA = 0,035). ConclusĂŁo: neste estudo, a versĂŁo portuguesa do Nursing Activities Score revelou-se um instrumento vĂĄlido, permitindo avaliar a carga de trabalho dos enfermeiros com segurançaObjetivo: describir el proceso de adaptaciĂłn y validaciĂłn del Nursing Activities Score al contexto portuguĂ©s. MĂ©todo: estudio piloto de adaptaciĂłn y validaciĂłn del Nursing Activities Score, con muestra de 67 pacientes internados en unidades de cuidados intensivos de tres hospitales portugueses. La validez del constructo se evaluĂł mediante anĂĄlisis factorial y por consistencia interna de los Ă­tems evaluados a travĂ©s del coefi ciente Alpha de Cronbach. Resultados: se obtuvo un valor medio de carga de trabajo de 63,04% (SD=14,25; Mediana=61,30). Los datos psicomĂ©tricos expresaron un Alpha de Cronbach de 0,71 en la escala total, indicando fi delidad aceptable. El anĂĄlisis factorial confi rmatorio sugiriĂł un ajuste adecuado entre el modelo y os datos (χ2 (199)=214,5; p=0,214; CFI=0,95; RMSA=0,035). ConclusiĂłn: en este estudio, la versiĂłn portuguesa del Nursing Activities Score demostrĂł ser un instrumento vĂĄlido, permitiendo evaluar la carga de trabajo de los enfermeros con precisiĂłn

    Study of the 6He+9Be and 7Be+9Be collisions

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    We present elastic scattering angular distributions of the 6He+9Be and 7Be+9Be reactions at Elab =16.2 MeV and Elab =23.7 MeV respectively. The 6He+9Be measurements have been performed at the Pelletron Laboratory of the Institute of Physics of the University of Sao Paulo, Brazil, using the Radioactive Ion Beams in Brasil (RIBRAS) facility and the 7Be+9Be system has beenmeasured at CRC Radioactive Beam Facility at Louvain-la-Neuve,Belgium. An OpticalModel analysis has been performed to obtain the nuclear potentials for both systems. A coupled-channel calculation was performed for the 7Be+9Be system taking into account the coupling to the first excited state and breakup channels of the 7Be nucleus. Keywords: Radioctive Beams. Exotic Nuclei. Nuclear Halo. Long range absorption. Elastic Scattering. Optical potential. Coupled channels calculations. PACS: 25.60.-t,25.60.Bx,25.70.Bc,29.38.-c,24.10.E

    Standalone vertex ïŹnding in the ATLAS muon spectrometer

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    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

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

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ Îł, H → Z Z∗ →4l and H →W W∗ →lÎœlÎœ. 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 ïŹts 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

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

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    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 Ό\mu) with large missing transverse energy and at least four jets, and dilepton (eeee, ΌΌ\mu\mu or eΌe\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

    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

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    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
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