366 research outputs found

    The “Horizon-T” Experiment: Extensive Air Showers Detection

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    Horizon - T is a n innovative detector system constructed to study Extensive Air Showers (EAS) in the energy range above 10 16 eV coming from a wide range of zenith angles (0 o - 85 o ). The system is located at Tien Shan high - altitude Science Station of Lebedev Physical Institute of the Russian Academy of Sciences at approximately 3340 meters above the sea level. It consists of eight charged particle detection points separated by the distance up to one kilometer as well as optical detector subsystem to view the Vavilov - Cherenkov light from the EAS. The time resolution of charged particles and Vavilov - Cherenkov light photons passage of the detector system is a few ns. This level of resolution allows conducting research of atmos pheric development of individual EAS

    Accelerating Universe with spacetime torsion but without dark matter and dark energy

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    It is shown that cosmological equations for homogeneous isotropic models deduced in the framework of the Poincar\'e gauge theory of gravity by certain restrictions on indefinite parameters of gravitational Lagrangian take at asymptotics the same form as cosmological equations of general relativity theory for ΛCDM\Lambda CDM-model. Terms related to dark matter and dark energy in cosmological equations of standard theory for ΛCDM\Lambda CDM-model are connected in considered theory with the change of gravitational interaction provoked by spacetime torsion.Comment: 4 page

    Experimental Evidence of Giant Electron - Gamma Bursts Generated by Extensive Atmospheric Showers in Thunderclouds

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    The existence of a new phenomena - giant electron-gamma bursts is established. The bursts are generated in thunderclouds as a result of the combined action of runaway breakdown and extensive atmosphere showers (RB-EAS). The experiments were fulfilled at the Tien Shan Mountain Scientific Station using EAS-Radio installation. This specially constructed installation consists of a wide spread EAS trigger array and a high time resolution radiointerferometer.Comment: 30 pages, 16 figure

    СОЧЕТАНИЕ ОТКРЫТОЙ И ВИДЕОХИРУРГИИ ПРИ ОПУХОЛЯХ ТОРАКОАБДОМИНАЛЬНОЙ ЛОКАЛИЗАЦИИ У ДЕТЕЙ

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    The autors report original date on the combined use of videosurgery and open surgical intervention in 3 patients. One (1 yr 10 mo) had neuroblastoma in the posterior mediastinum spreading to the retroperitoneal region, another (5 yr) presented with neuroblastoma in the thoracic aperture region spreading to the neck, the third one (14 yr) suffered limphoepithelioma-like cancer of the thymus. The combined treatment permits to optimize the surgical procedure and avoid additional use of thoraco- and laparotomy.Описаны собственные наблюдения по сочетанному использованию видеохирургии и открытого хирургического вмешательства у 3-х пациентов: с нейробластомой заднего средостения  с распространениемв забрюшинное пространство (возраст 1 год 10 мес); с нейробластомой зоны апертуры грудной клетки сраспорстранением на шею (5 лет) и  с лимфоэпителиомо-подобным раком тимуса (14 лет). Показано, что методика позволяет оптимизировать операцию и избежать дополнительного использования торако- или лапаротомии

    Accelerating units for commercial resonator LINACs model UELR-10-10S designed for radiation sterilization development and results of testing

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    Some specific design features of the accelerating units for LINACs model UELR-10-10S designed for radiation sterilization and the electron beam characteristics obtained experimentally are considered.Описываются некоторые особенности конструкции ускорителей модели УЭЛР-10-10С, приводятся и обсуждаются характеристики электронного пучка, полученные экспериментально.Описуються деякі особливості конструкції прискорювачів моделі УЕЛР-10-10С, приводяться і обговорюються характеристики електронного пучка, отримані експериментально

    The C-80 cyclotron system. Current status

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    The C-80 cyclotron system is intended to produce proton beams with an energy ranging from 40 up to 80 MeV and current up to 200 μA. The beams with the aforementioned parameters will be used for commercial production of a wide assortment of isotopes for medicine including radiation generators. In addition, creation of a special beamline to form homogeneous proton beams of ultra-low intensity (10⁷…10⁹) will allow the proton therapy of eye diseases and superficial oncological diseases as well as tests of radioelectronic components for radiation resistance to be performed. The equipment of the cyclotron and the first section of the beam transport system has been manufactured, tested at test facilities in the Efremov Institute, installed in the PNPI and made ready for acceptance tests.Циклотронный комплекс Ц-80 предназначен для получения протонных пучков с энергией 40…80 МэВ и током до 200 мкА. Пучки с такими параметрами будут использоваться для производства широкого спектра изотопов медицинского назначения, в том числе генераторов излучения, в коммерческих масштабах. Кроме того, создание специального тракта формирования гомогенных пучков протонов ультрамалой интенсивности (10⁷…10⁹) позволит осуществлять протонную лучевую терапию глаза и поверхностных форм онкологических заболеваний, а также проводить испытания радиоэлектронных изделий на радиационную стойкость. Оборудование циклотрона и первого участка системы транспортировки изготовлено и испытано на стендах НИИЭФА им. Д.В. Ефремова, смонтировано в ПИЯФ им. Б.П. Константинова и подготовлено для проведения приемосдаточных испытаний.Циклотронний комплекс Ц-80 призначений для отримання протонних пучків з енергією 40...80 МеВ і струмом до 200 мкА. Пучки з такими параметрами використовуватимуться для виробництва широкого спек-тра ізотопів медичного призначення, у тому числі генераторів випромінювання, в комерційних масштабах. Крім того, створення спеціального тракту формування гомогенних пучків протонів ультрамалої інтенсивності (10⁷…10⁹) дозволить здійснювати протонну променеву терапію ока і поверхневих форм онкологічних захворювань, а також проводити випробування радіоелектронних виробів на радіаційну стійкість. Устаткування циклотрона і першої ділянки системи транспортування виготовлене та випробуване на стендах НДІЕФА ім. Д.В. Єфремова, змонтовано в ПІЯФ ім. Б.П. Константинова і підготовлено для проведення приймальноздавальних випробувань

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

    Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

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    We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters
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