4,533 research outputs found

    Cryogenic characterization of Hamamatsu HWB MPPCs for the DUNE photon detection system

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    International audienceThe Deep Underground Neutrino Experiment (DUNE) is a nextgeneration experiment aimed to study neutrino oscillation. Itslong-baseline configuration will exploit a Near Detector (ND) and aFar Detector (FD) located at a distance of ∼1300 km. The FDwill consist of four Liquid Argon Time Projection Chamber (LAr TPC)modules. A Photon Detection System (PDS) will be used to detect thescintillation light produced inside the detector after neutrinointeractions. The PDS will be based on light collectors coupled toSilicon Photomultipliers (SiPMs). Different photosensortechnologies have been proposed and produced in order to identifythe best samples to fullfill the experiment requirements. In thispaper, we present the procedure and results of a validation campaignfor the Hole Wire Bonding (HWB) MPPCs samples produced by HamamatsuPhotonics K.K. (HPK) for the DUNE experiment, referring to them as`SiPMs'. The protocol for a characterization at cryogenictemperature (77 K) is reported. We present the down-selectioncriteria and the results obtained during the selection campaignundertaken, along with a study of the main sources of noise of theSiPMs including the investigation of a newly observed phenomenon inthis field

    Electron and photon energy calibration with the ATLAS detector using LHC Run 2 data

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    This paper presents the electron and photon energy calibration obtained with the ATLAS detector using 140 fb-1 of LHC proton-proton collision data recorded at √(s) = 13 TeV between 2015 and 2018. Methods for the measurement of electron and photon energies are outlined, along with the current knowledge of the passive material in front of the ATLAS electromagnetic calorimeter. The energy calibration steps are discussed in detail, with emphasis on the improvements introduced in this paper. The absolute energy scale is set using a large sample of Z-boson decays into electron-positron pairs, and its residual dependence on the electron energy is used for the first time to further constrain systematic uncertainties. The achieved calibration uncertainties are typically 0.05% for electrons from resonant Z-boson decays, 0.4% at ET ∼ 10 GeV, and 0.3% at ET ∼ 1 TeV; for photons at ET ∼ 60 GeV, they are 0.2% on average. This is more than twice as precise as the previous calibration. The new energy calibration is validated using J/ψ → ee and radiative Z-boson decays

    Observation of Wγγ triboson production in proton-proton collisions at s=13 TeV with the ATLAS detector