148 research outputs found

    Modelling CC neutrino cross sections in the few GeV energy region

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    Selected problems in modelling neutrino-nucleon and -nuclei cross sections in the neutrino energy region of the few GeV are reviewed.Comment: Presented by J.T. Sobczyk at the Cracow Epiphany Conference on Neutrinos and Dark Matter, Jan. 5-8, 2006, Cracow, Polan

    Off-axis characterisation of the CERN T10 beam for low momentum proton measurements with a High Pressure Gas Time Projection Chamber

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    We present studies of proton fluxes in the T10 beamline at CERN. A prototype high pressure gas time projection chamber was exposed to the beam of protons and other particles, using the 0.8 GeV/c momentum setting in T10, in order to make cross section measurements of low energy protons in argon. To explore the energy region comparable to hadrons produced by GeV-scale neutrino interactions at oscillation experiments, i.e. near 0.1 GeV of kinetic energy, methods of moderating the T10 beam were employed: the dual technique of moderating the beam with acrylic blocks and measuring scattered protons off the beam axis was used to decrease the kinetic energy of incident protons, as well aschange the proton/minimum ionising particle (MIP) composition of the incident flux. Measurements of the beam properties were made using time of flight systems upstream and downstream of the TPC. The kinetic energy of protons reaching the TPC was successfully changed from ∼0.3 GeV without moderator blocks to less than 0.1 GeV with four moderator blocks (40 cm path length). The flux of both protons and MIPs off the beam axis was increased. The ratio of protons to MIPs vary as a function of the off-axis angle allowing for possible optimisation of the detector to select the type of required particles. Simulation informed by the time of flight measurements show that with four moderator blocks placed in the beamline, (5.6 ± 0.1) protons with energies below 0.1 GeV per spill traversed the active TPC region. Measurements of the beam composition and energy are presented

    Effect of bed particle size on heat transfer between fluidized bed of group b particles and vertical rifled tubes

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    The effect of bed particle size on the local heat transfer coefficient between a fluidized bed and vertical rifled tubes (38mm-O.D.) has been determined in a large-scale circulating fluidized bed (CFB) reactor. Bed particles with different Sauter mean particle diameter within the range of 0.219-0.411mm and particle density in the range of 2660-2750 kg/m3 were used as bed material in this heat transfer study. A gas fluidized bed furnace with 27.6´10.6m cross-section above refractory line and 48m in height was used. Air coal firing conditions at the membrane wall in the form of water tubes welded with lateral fins corresponded to a suspension density covering the range of 1.36-6.22kg/m3, furnace temperatures in the range of 1080-1164K, a superficial gas velocity varied from 3.13 to 5.11m/s and solids circulation flux covered a range of 22.3-26.2kg/m2s. For these operating conditions, the heat transfer analysis of CFB reactor with detailed analysis of bed-to-wall heat transfer coefficient along furnace height was investigated. In this work, the overall heat transfer coefficient was estimated using a mechanistic heat transfer model based on cluster renewal approach (1,2). The experimental results (Figs. 1-4) show that: (1) higher heat transfer coefficients along furnace height were found under finer bed particles size dp\u3c0.241mm, (2) heat transfer data confirms strong dependency of the overall heat transfer coefficient on suspension density and also hydrodynamic conditions within CFB furnace, (3) for small bed particles, dp\u3c0.233mm, the particle convection component plays dominant role in heat transfer mechanism, (4) for large bed particles, dp\u3e0.366mm, the effect of particle size on contribution of radiation from dispersed phase become essential with particle diameter increasing, and (5) for all bed particles with diameters in the range of 0.240-0.411mm, the gas convection heat transfer coefficient between the fluidized bed (Geldart B particles) and the rifled tubes increased as the bed particles size increased. REFERENCES 1.A. Blaszczuk, W. Nowak and Sz. Jagodzik. Bed-to-wall heat transfer coefficient in a supercritical circulating fluidised bed boiler. Chem. Process. Eng., 35(2):191-204, 2014. 2.A. Blaszczuk, W. Nowak. Heat transfer behavior inside a furnace chamber of large-scale supercritical CFB reactor. Int. J. Heat Mass Transfer, 87:464-480, 2015 Please click Additional Files below to see the full abstract

    The Research of CFB Boiler Operation for Oxygen Enhanced Dried Lignite Combustion

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    The paper presents the research of CFB boiler operation for oxygen-enhanced dried lignite combustion. The combustion in oxygen-enhanced conditions generally leads to reducing the emissions of CO and NOx and N2O due to reduced volume of flue gas. The maximum oxygen content for oxygen-enhanced combustion in O2/N2 conditions should not exceed 60%, however, the maximum drying extent of fuel should not be higher than 50% of the initial moisture content in an examined lignite

    Updated MiniBooNE Neutrino Oscillation Results with Increased Data and New Background Studies

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    The MiniBooNE experiment at Fermilab reports a total excess of 638.0±132.8 electron-like events (4.8σ) from a data sample corresponding to 18.75×1020 protons-on-target in neutrino mode, which is a 46% increase in the data sample with respect to previously published results, and 11.27 × 1020 protons-on-target in antineutrino mode. The additional statistics allow several studies to address questions on the source of the excess. First, we provide two-dimensional plots in visible energy and cosine of the angle of the outgoing lepton, which can provide valuable input to models for the event excess. Second, we test whether the excess may arise from photons that enter the detector from external events or photons exiting the detector from π0 decays in two model independent ways. Beam timing information shows that almost all of the excess is in time with neutrinos that interact in the detector. The radius distribution shows that the excess is distributed throughout the volume, while tighter cuts on the fiducal volume increase the significance of the excess. We conclude that models of the event excess based on entering and exiting photons are disfavored

    H-index in medicine is driven by original research

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    Aim To investigate the contribution of selected types of articles to h-indices of medical researchers. Methods We used the Web of Science to export the publication records of various members from 26 scientific medical societies (13 European, 13 North American) associated with 13 medical specialties. Those included were presidents (n = 26), heads of randomly chosen committees (n = 52), and randomly selected members of those committees (n = 52). Publications contributing to h-index were categorized as research articles, reviews, guidelines, metaanalyses, or other published work. Results Overall, 3259 items authored by 129 scholars were analyzed. The median h-index was 19.5. The median contribution of research articles to h-index was 84.4%. Researchers in the upper h-index tercile (≥28.5) had a larger share of research articles that contributed to h-index in comparison with those in the lower h-index tercile (≤12.5) (median 87.3% [1st-3rd quartile: 80.0%-93.1%] vs 80.0% [50.0%- 88.9%], P = 0.015). We observed an analogous difference with regard to guidelines (1.1% [0%-3.7%] vs 0% [0%-0%], P = 0.007). Conclusions Original research drives h-indices in medicine. Although guidelines contribute to h-indices in medicine, their influence is low. The specific role of randomized controlled trials in building h-index in medicine remains to be assessed

    Four Momentum Transfer Discrepancy in the Charged Current π+\pi^+ Production in the MiniBooNE: Data vs. Theory

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    The MiniBooNE experiment has collected what is currently the world's largest sample of neutrino muon charged current single charged pion interactions, roughly 46,000 events. The purity of the CC1pi+ sample is 87% making this the purest event sample observed in the MiniBooNE detector. The average energy of neutrinos producing CC1pi+ interactions in MiniBooNE is about 1 GeV, therefore the study of these events can provide insight into both resonant and coherent pion production processes. In this talk, we will discuss the long-standing discrepancy in four-momentum transfer observed between CC1pi+ data and existing predictions. Several attempts to address this problem will be presented. Specifically, the Rein-Sehgal model has been extended to include muon mass terms for both resonant [Kuzmin et al. and Berger and Sehgal] and coherent production. Using calculations from Graczyk and Sobczyk paper, an updated form for the vector form factor [Lalakulich et al.] has also been adopted. The results of this improved description of CC1pi+ production will be compared to the high statistics MiniBooNE CC1pi+ data and several existing parametrisations of the axial vector form factor.Comment: Presented at 6th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NUINT 2009), Sitges, Barcelona, Spain, 18-22 May 2009. Submitted to AIP Conf.Pro
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