Kyungpook National University

About: Kyungpook National University is a education organization based out in Daegu, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 20497 authors who have published 42107 publications receiving 834608 citations.

Search for Heavy Neutral Leptons in Events with Three Charged Leptons in Proton-Proton Collisions at √s = 13 TeV

Abstract: A search for a heavy neutral lepton N of Majorana nature decaying into a W boson and a charged lepton is performed using the CMS detector at the LHC. The targeted signature consists of three prompt charged leptons in any flavor combination of electrons and muons. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV, with an integrated luminosity of 35.9 fb^(−1). The search is performed in the N mass range between 1 GeV and 1.2 TeV. The data are found to be consistent with the expected standard model background. Upper limits are set on the values of |V_(eN)|^2and |V_(μN)|^2, where V_(lN) is the matrix element describing the mixing of N with the standard model neutrino of flavor l. These are the first direct limits for N masses above 500 GeV and the first limits obtained at a hadron collider for N masses below 40 GeV.

Observation of Energy and Baseline Dependent Reactor Antineutrino Disappearance in the RENO Experiment.

Abstract: The RENO experiment has analyzed about 500 live days of data to observe an energy dependent disappearance of reactor ν[over ¯]_{e} by comparing their prompt signal spectra measured in two identical near and far detectors In the period between August of 2011 and January of 2013, the far (near) detector observed 31 541 (290 775) electron antineutrino candidate events with a background fraction of 49% (28%) The measured prompt spectra show an excess of reactor ν[over ¯]_{e} around 5 MeV relative to the prediction from a most commonly used model A clear energy and baseline dependent disappearance of reactor ν[over ¯]_{e} is observed in the deficit of the observed number of ν[over ¯]_{e} Based on the measured far-to-near ratio of prompt spectra, we obtain sin^{2}2θ_{13}=0082±0009(stat)±0006(syst) and |Δm_{ee}^{2}|=[262_{-023}^{+021}(stat)_{-013}^{+012}(syst)]×10^{-3} eV^{2}

Reductive defluorination of aqueous perfluorinated alkyl surfactants: effects of ionic headgroup and chain length.

Abstract: Perfluorinated chemicals (PFCs) are distributed throughout the environment. In the case of perfluorinated alkyl carboxylates and sulfonates, they can be classified as persistent organic pollutants since they are resistant to environmentally relevant reduction, oxidation, and hydrolytic processes. With this in mind, we report on the reductive defluorination of perfluorobutanoate, PFBA (C_3F_7CO_2−), perfluorohexanoate, PFHA (C_5F_(11)CO_2−), perfluorooctanoate, PFOA (C_7F_(15)CO_2−), perfluorobutane sulfonate, PFBS (C_4F_9SO_3−), perfluorohexane sulfonate, PFHS (C_6F_(13)SO_3−), and perfluorooctane sulfonate, PFOS (C_8F_(17)SO_3−) by aquated electrons, eaq−, that are generated from the UV photolysis (λ = 254 nm) of iodide. The ionic headgroup (-SO_3− vs -CO_2−) has a significant effect on the reduction kinetics and extent of defluorination (F index = −[F−]_(produced)/[PFC]_(degraded)). Perfluoroalkylsulfonate reduction kinetics and the F index increase linearly with increasing chain length. In contrast, perfluoroalkylcarboxylate chain length appears to have a negligible effect on the observed kinetics and the F index. H/F ratios in the gaseous fluoro-organic products are consistent with measured F indexes. Incomplete defluorination of the gaseous products suggests a reductive cleavage of the ionic headgroup occurs before complete defluorination. Detailed mechanisms involving initiation by aquated electrons are proposed.