177 research outputs found

    Scaling of the F_2 structure function in nuclei and quark distributions at x>1

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    We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for x>1x>1, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.Comment: 5 pages, 4 figures, to be submitted to physical revie

    A CO2 sensing module modulates ÎČ-1,3-glucan exposure in Candida albicans.

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    This work was funded by a program grant to A.J.P.B., N.A.R.G., L.P.E., and M.G.N. from the UK Medical Research Council [www.mrc.ac.uk: MR/M026663/1, MR/M026663/2]. The work was also supported by the Medical Research Council Centre for Medical Mycology [MR/N006364/1, MR/N006364/2], by a grant to C.d.E. from the European Commission [FunHoMic: H2020-MSCA-ITN-2018–812969], and by the Wellcome Trust via Investigator, Collaborative, Equipment, Strategic and Biomedical Resource awards [www.wellcome.ac.uk: 075470, 086827, 093378, 097377, 099197, 101873, 102705, 200208, 217163, 224323]. Work in the d’Enfert laboratory was supported by grants from the Agence Nationale de Recherche (ANR-10-LABX-62-IBEID) and the Swiss National Science Foundation (Sinergia CRSII5_173863/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission.Peer reviewedPublisher PD

    Large enhancement of deuteron polarization with frequency modulated microwaves

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    We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liters polarized target using the method of dynamic nuclear polarization. This target was used during a deep inelastic polarized muon-deuteron scattering experiment at CERN. Measurements of the electron paramagnetic resonance absorption spectra show that frequency modulation gives rise to additional microwave absorption in the spectral wings. Although these results are not understood theoretically, they may provide a useful testing ground for the deeper understanding of dynamic nuclear polarization.Comment: 10 pages, including the figures coming in uuencoded compressed tar files in poltar.uu, which also brings cernart.sty and crna12.sty files neede

    New measurements of the EMC effect in very light nuclei

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    New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from 2H, 3He, 4He, 9Be and 12C for 0.3<x<0.9, Q^2 approximately 3-6 GeV^2. These data represent the first measurement of the EMC effect for 3He at large x and a significant improvement for 4He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.Comment: 5 pages, 4 figures, submitted to PRL. fixed error in author list, minor text revisio

    Measurements of Non-Singlet Moments of the Nucleon Structure Functions and Comparison to Predictions from Lattice QCD for Q2=4Q^2 = 4 GeV2\rm GeV^2

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    We present extractions of the nucleon non-singlet moments utilizing new precision data on the deuteron F2F_2 structure function at large Bjorken-xx determined via the Rosenbluth separation technique at Jefferson Lab Experimental Hall C. These new data are combined with a complementary set of data on the proton previously measured in Hall C at similar kinematics and world data sets on the proton and deuteron at lower xx measured at SLAC and CERN. The new Jefferson Lab data provide coverage of the upper third of the xx range, crucial for precision determination of the higher moments. In contrast to previous extractions, these moments have been corrected for nuclear effects in the deuteron using a new global fit to the deuteron and proton data. The obtained experimental moments represent an order of magnitude improvement in precision over previous extractions using high xx data. Moreover, recent exciting developments in Lattice QCD calculations provide a first ever comparison of these new experimental results with calculations of moments carried out at the physical pion mass, as well as a new approach which first calculates the quark distributions directly before determining moments

    First measurement of quasi-elastic Λ\Lambda baryon production in muon anti-neutrino interactions in the MicroBooNE detector

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    We present the first measurement of the cross section of Cabibbo-suppressed Λ\Lambda baryon production, using data collected with the MicroBooNE detector when exposed to the neutrinos from the Main Injector beam at the Fermi National Accelerator Laboratory. The data analyzed correspond to 2.2×10202.2 \times 10^{20} protons on target of neutrino mode running and 4.9×10204.9 \times 10^{20} protons on target of anti-neutrino mode running. An automated selection is combined with hand scanning, with the former identifying five candidate Λ\Lambda production events when the signal was unblinded, consistent with the GENIE prediction of 5.3±1.15.3 \pm 1.1 events. Several scanners were employed, selecting between three and five events, compared with a prediction from a blinded Monte Carlo simulation study of 3.7±1.03.7 \pm 1.0 events. Restricting the phase space to only include Λ\Lambda baryons that decay above MicroBooNE's detection thresholds, we obtain a flux averaged cross section of 2.0−1.7+2.2×10−402.0^{+2.2}_{-1.7} \times 10^{-40} cm2/^2/Ar, where statistical and systematic uncertainties are combined

    First demonstration of O(1 ns)\mathcal{O}(1\,\text{ns}) timing resolution in the MicroBooNE liquid argon time projection chamber

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    MicroBooNE is a neutrino experiment located in the Booster Neutrino Beamline (BNB) at Fermilab, which collected data from 2015 to 2021. MicroBooNE's liquid argon time projection chamber (LArTPC) is accompanied by a photon detection system consisting of 32 photomultiplier tubes used to measure the argon scintillation light and determine the timing of neutrino interactions. Analysis techniques combining light signals and reconstructed tracks are applied to achieve a neutrino interaction time resolution of O(1 ns)\mathcal{O}(1\,\text{ns}). The result obtained allows MicroBooNE to access the ns neutrino pulse structure of the BNB for the first time. The timing resolution achieved will enable significant enhancement of cosmic background rejection for all neutrino analyses. Furthermore, the ns timing resolution opens new avenues to search for long-lived-particles such as heavy neutral leptons in MicroBooNE, as well as in future large LArTPC experiments, namely the SBN program and DUNE
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