166 research outputs found

    Single spin asymmetry measurements for π0\pi^0 inclusive productions in p+pπ0+Xp+p_{\uparrow} \to \pi^0 + X and \pi^-+\p_{\uparrow}\to \pi^0+X reactions at 70 and 40 GeV respectively

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    The inclusive π0\pi^0 asymmetries were measured in reactions p+pπ0+Xp+p\uparrow \to \pi^0+X and π+pπ0+X\pi^-+p\uparrow \to \pi^0+X at 70 and 40 GeV/c respectively. The measurements were made at the central region (for the first reaction) and asymmetry is compatible with zero in the entire measured pTp_T region. For the second reaction the asymmetry is zero for small xFx_F region (0.4<xF<0.1,0.5<pT(GeV/c)<1.5-0.4<x_F<-0.1, 0.5<p_T(GeV/c) <1.5) and increases with growth of xF\mid x_F\mid. Averaged over the interval 0.8<xF<0.4,1<pT(GeV/c)<2-0.8<x_F<-0.4, 1<p_T(GeV/c)<2 the asymmetry was (13.8±3.8)-(13.8\pm 3.8)%.Comment: 4 pages, 2 figures; Presented at SPIN-2004 at Trieste, October 10-16,200

    A Precision Measurement of the Neutron Twist-3 Matrix Element d2nd_2^n: Probing Color Forces

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    Double-spin asymmetries and absolute cross sections were measured at large Bjorken xx (0.25 x \le x \le 0.90), in both the deep-inelastic and resonance regions, by scattering longitudinally polarized electrons at beam energies of 4.7 and 5.9 GeV from a transversely and longitudinally polarized 3^3He target. In this dedicated experiment, the spin structure function g2g_2 on 3^3He was determined with precision at large xx, and the neutron twist-three matrix element d2nd_2^n was measured at \left of 3.21 and 4.32 GeV2^2/c2c^2, with an absolute precision of about 10510^{-5}. Our results are found to be in agreement with lattice QCD calculations and resolve the disagreement found with previous data at \left = 5 GeV2^2/c2c^2. Combining d2nd_2^n and a newly extracted twist-four matrix element, f2nf_2^n, the average neutron color electric and magnetic forces were extracted and found to be of opposite sign and about 30 MeV/fm in magnitude.Comment: Corrected a typo in the author list and Figure 1 legend. 6 pages, 2 figures, 2 table

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Performance and Operation of the CMS Electromagnetic Calorimeter

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    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

    First measurement of muon-neutrino disappearance in NOvA

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    This paper reports the first measurement using the NOvA detectors of νμ disappearance in a νμ beam. The analysis uses a 14 kton-equivalent exposure of 2.74×1020 protons-on-target from the Fermilab NuMI beam. Assuming the normal neutrino mass hierarchy, we measure Δm232=(2.52+0.20−0.18)×10−3  eV2 and sin2θ23 in the range 0.38–0.65, both at the 68% confidence level, with two statistically degenerate best-fit points at sin2θ23=0.43 and 0.60. Results for the inverted mass hierarchy are also presented

    First measurement of electron neutrino appearance in NOvA

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    We report results from the first search for νμ→νe transitions by the NOvA experiment. In an exposure equivalent to 2.74×1020 protons on target in the upgraded NuMI beam at Fermilab, we observe 6 events in the Far Detector, compared to a background expectation of 0.99±0.11(syst) events based on the Near Detector measurement. A secondary analysis observes 11 events with a background of 1.07±0.14(syst). The 3.3σ excess of events observed in the primary analysis disfavors 0.1π<δCP<0.5π in the inverted mass hierarchy at the 90% C.L
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