68 research outputs found

    Features of climate and geographical distribution of atmospheric precipitations in the south of Ukraine

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    Formulation of the problem. The concept of implementing state policy in the field of climate change until 2030, which aims to develop a national climate program and prevent the reduction of risks associated with them in different regions of Ukraine. The research was performed in accordance with the objectives formulated in the research works of Odessa State Ecological University on the following topics: «Regime of precipitation in the regions of Ukraine in the late XX and early XXI centuries» (№ SR 0111U000590); «Forecasting of dangerous meteorological phenomena over the southern regions of Ukraine» (№ SR 00115U006532); «Comprehensive method of probabilistic and prognostic modeling of extreme hydrological phenomena on the rivers of southern Ukraine to ensure sustainable water use in climate change» (№ SR 0121U010964). Problems of further research. The results presented in the article, of course, can not be considered exhaustive in terms of determining the impact of only two climatic signals that can form the spatial distribution of precipitation in southern Ukraine. The solution of the problems in the future will be directed to the consideration of other known teleconnections of the Northern and Southern Hemispheres with the involvement of additional equidistant empirical data. The purpose. This article aims to identify the features of the spatial distribution of precipitation in the winter season and determine the responses of climatic signals (North Atlantic and North Caspian fluctuations) in their fields in southern Ukraine (Odessa, Mykolaiv, Kherson, Zaporizhia region and the Autonomous Republic of Crimea). Research methods. The implementation of an integrated statistical approach was carried out in three stages with the involvement of methods of multidimensional statistical and cartographic analysis and methods of research of non-stationary random processes. The subject of the study is the series of monthly precipitation for December, January, February at 40 stations in Ukraine and time series of average values of climatic indices of large-scale interaction in the field of pressure - North Atlantic (NAO) and North Caspian (NCP) fluctuations for each month of the period 1962-2006. Presentation of the main research material. Objective clustering of the territory of Ukraine has been carried out on the basis of long-term empirical data on precipitation. In the south, 2 generalized clusters have been identified, each of which is statistically sound and characterized by a time series of the mean vector. The statistical structure of these series is analyzed, which allowed to predict future trends in the studied fields until 2025-2030 in the territory of Southern Ukraine. Studies of the impact of North Atlantic and Euro-Mediterranean macro-processes on the spatial distribution of the monthly amount of precipitation in the winter season show the complexity and ambiguity of these relationships in different months of the season and in different regions of southern Ukraine. Practical value. The obtained statistical models in the form of maps-schemes will take into account the directions of transfer of basic substances, which in turn will help (in compiling the climate forecast of precipitation) to understand the contribution of different regions of the Northern Hemisphere to the formation of the main climatic indicator. Research results. In the south of Ukraine in December and February the monthly rainfall by 2025-2030 will decrease compared to the beginning of the XXI century. In January, only in the Zaporozhye region is expected to fall rainfall in the next 20-30 years. For the rest of the southern regions of Ukraine in January the amount of precipitation will be within long-term values (15-45 mm). The presence of a linear correlation between the North Atlantic Oscillation and the spatial distribution of precipitation in December was determined (with a probability of 90%); in February, the combined effects of the North Sea-Caspian and North Atlantic oscillations. In January, in the south of Ukraine, with some probability, it was not possible to establish responses in the distribution of precipitation with the climatic signals under consideration

    Magnetic field driven 2D-3D crossover in the S=12 frustrated chain magnet LiCuVO4

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    We report on a heat-capacity study of high-quality single-crystal samples of LiCuVO4 — a frustrated spin S = 1/2 chain system—in a magnetic field amounting to 3/4 of the saturation field. A detailed examination of magnetic phase transitions observed in this field range shows that although the low-field helical state clearly has three-dimensional properties, the field-induced spin-modulated phase turns out to be quasi-two-dimensional. The model proposed in this paper allows one to qualitatively understand this crossover, thus eliminating the presently existing contradictions in the interpretations of NMR and neutron-scattering measurements

    Aligning the CMS Muon Endcap Detector with a System of Optical Sensors

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    The positions and orientations of one sixth of 468 large cathode strip chambers in the endcaps of the CMS muon detector are directly monitored by several hundred sensors including 2-D optical sensors with linear CCDs illuminated by cross-hair lasers. Position measurements obtained by photogrammetry and survey under field-off conditions show that chambers in the +Z endcap have been placed on the yoke disks with an average accuracy of 1\approx 1 mm in all 3 dimensions. We reconstruct absolute ZCMS_{CMS} positions and orientations of chambers at B=0T and B=4T using data from the optical alignment system. The measured position resolution and sensitivity to relative motion is about 60 μm\mu m. The precision for measuring chamber positions taking into account mechanical tolerances is \mbox{270μm\approx 270 \mu m}. Comparing reconstruction of optical alignment data and photogrammetry measurements at B=0T indicates an accuracy of \approx 680 μm\mu m currently achieved with the hardware alignment system. Optical position measurements at B=4T show significant chamber displacements of up to 13 mm due to yoke disk deformation

    Design and Performance of the Alignment System for the CMS Muon Endcaps

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    The alignment system for the CMS Muon Endcap detector employs several hundred sensors such as optical 1-D CCD sensors illuminated by lasers and analog distance- and tilt-sensors to monitor the positions of one sixth of 468 large Cathode Strip Chambers. The chambers mounted on the endcap yoke disks undergo substantial deformation on the order of centimeters when the 4T field is switched on and off. The Muon Endcap alignment system is required to monitor chamber positions with \mbox{75-200 μ\mum} accuracy in the Rϕ\phi plane, \approx400 μ\mum in the radial direction, and \approx1 mm in the z-direction along the beam axis. The complete alignment hardware for one of the two endcaps has been installed at CERN. A major system test was performed when the 4T solenoid magnet was ramped up to full field for the first time in August 2006. We present the overall system design and first results on disk deformations, which indicate that the measurements agree with expectations

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Measurement of the W boson polarisation in ttˉt\bar{t} events from pp collisions at s\sqrt{s} = 8 TeV in the lepton + jets channel with ATLAS

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    Measurement of jet fragmentation in Pb+Pb and pppp collisions at sNN=2.76\sqrt{{s_\mathrm{NN}}} = 2.76 TeV with the ATLAS detector at the LHC

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    Search for new phenomena in events containing a same-flavour opposite-sign dilepton pair, jets, and large missing transverse momentum in s=\sqrt{s}= 13 pppp collisions with the ATLAS detector

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