2,899 research outputs found

    Large-scale Samples Irradiation Facility at the IBR-2 Reactor in Dubna

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    The irradiation facility at the beam line no.3 of the IBR-2 reactor of the Frank Laboratory for Neutron Physics is described. The facility is aimed at irradiation studies of various objects with area up to 800 cm2^2 both at cryogenic and ambient temperatures. The energy spectra of neutrons are reconstructed by the method of threshold detector activation. The neutron fluence and ő≥\gamma dose rates are measured by means of alanine and thermoluminescent dosimeters. The boron carbide and lead filters or (n/ő≥)(n/\gamma) converter provide beams of different ratio of doses induced by neutrons and photons. For the lead filter, the flux of fast neutrons with energy more than 0.1 MeV is 1.4‚čÖ10101.4 \cdot 10^{10} \fln and the neutron dose is about 96\% of the total radiation dose. For the (n/ő≥)(n/\gamma) converter, the ő≥\gamma dose rate is ‚ąľ\sim500 Gy h‚ąí1^{-1} which is about 85\% of the total dose. The radiation hardness tests of GaAs electronics and materials for the ATLAS detector to be put into operation at the Large Hadron Collider (LHC) have been performed successfully at this facility

    Spin Physics Experiments at NICA-SPD with polarized proton and deuteron beams

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    We propose to perform measurements of asymmetries of the Drell-Yan (DY) pairs production in collisions of non-polarized, longitudinally and transversally polarized protons and deuterons which provide an access to all leading twist collinear and TMD PDFs of quarks and anti-quarks in nucleons. The measurements of asymmetries in production of J/\Psi and direct photons will be performed as well simultaneously with DY using dedicated triggers. The set of these measurements will supply complete information for tests of the quark-parton model of nucleons at the QCD twist-two level with minimal systematic errors.Comment: Letter of Intent, 54 pages, 54 fugure

    Relative luminosity measurement of the LHC with the ATLAS forward calorimeter

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    In this paper it is shown that a measurement of the relative luminosity changes at the LHC may be obtained by analysing the currents drawn from the high voltage power supplies of the electromagnetic section of the forward calorimeter of the ATLAS detector. The method was verified with a reproduction of a small section of the ATLAS forward calorimeter using proton beams of known beam energies and variable intensities at the U-70 accelerator at IHEP in Protvino, Russia. The experimental setup and the data taking during a test beam run in April 2008 are described in detail. A comparison of the measured high voltage currents with reference measurements from beam intensity monitors shows a linear dependence on the beam intensity. The non-linearities are measured to be less than 0.5 % combining statistical and systematic uncertainties.Comment: 16 page

    Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method

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    This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/he/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within ¬Ī1\pm 1% of the true values and the fractional energy resolution is [(58¬Ī3)/E+(2.5¬Ī0.3)[(58\pm3)% /\sqrt{E}+(2.5\pm0.3)%]\oplus (1.7\pm0.2)/E. The value of the e/he/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74¬Ī0.041.74\pm0.04 and agrees with the prediction that e/h>1.7e/h > 1.7 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Polarised Quark Distributions in the Nucleon from Semi-Inclusive Spin Asymmetries

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    We present a measurement of semi-inclusive spin asymmetries for positively and negatively charged hadrons from deep inelastic scattering of polarised muons on polarised protons and deuterons in the range 0.0030.0031 GeV2^2. Compared to our previous publication on this subject, with the new data the statistical errors have been reduced by nearly a factor of two. From these asymmetries and our inclusive spin asymmetries we determine the polarised quark distributions of valence quarks and non-strange sea quarks at Q2Q^2=10 GeV2^2. The polarised uu valence quark distribution, őĒuv(x)\Delta u_v(x), is positive and the polarisation increases with xx. The polarised dd valence quark distribution, őĒdv(x)\Delta d_v(x), is negative and the non-strange sea distribution, őĒqňČ(x)\Delta \bar q(x), is consistent with zero over the measured range of xx. We find for the first moments ‚ąę01őĒuv(x)dx=0.77¬Ī0.10¬Ī0.08\int_0^1 \Delta u_v(x) dx = 0.77 \pm 0.10 \pm 0.08, ‚ąę01őĒdv(x)dx=‚ąí0.52¬Ī0.14¬Ī0.09\int_0^1 \Delta d_v(x) dx = -0.52 \pm 0.14 \pm 0.09 and ‚ąę01őĒqňČ(x)dx=0.01¬Ī0.04¬Ī0.03\int_0^1 \Delta \bar q(x) dx= 0.01 \pm 0.04 \pm 0.03, where we assumed őĒuňČ(x)=őĒdňČ(x)\Delta \bar u(x) = \Delta \bar d(x). We also determine for the first time the second moments of the valence distributions ‚ąę01xőĒqv(x)dx\int_0^1 x \Delta q_v(x) dx.Comment: 17 page

    Standalone vertex Ô¨Ānding in the ATLAS muon spectrometer