Browsing by Subject "Shadowing"

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  • The CMS collaboration; Sirunyan, A. M.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Talvitie, J.; Tuuva, T. (2018)
    The transverse momentum (p(T)) spectrum of prompt D-0 mesons and their antiparticles has been measured via the hadronic decay channels D-0 -> K- pi(+) and (D) over bar (0) -> K+ pi(-) in pp and PbPb collisions at a centre-of-mass energy of 5.02 TeV per nucleon pair with the CMS detector at the LHC. The measurement is performed in the D-0 meson p(T) range of 2-100GeV/c and in the rapidity range of vertical bar y vertical bar < 1. The pp (PbPb) dataset used for this analysis corresponds to an integrated luminosity of 27.4 pb(-1) (530 mu b(-1)). The measured D-0 meson p(T) spectrum in pp collisions is well described by perturbative QCD calculations. The nuclear modification factor, comparing D-0 meson yields in PbPb and pp collisions, was extracted for both minimum-bias and the 10% most central PbPb interactions. For central events, the D-0 meson yield in the PbPb collisions is suppressed by a factor of 5-6 compared to the pp reference in the p(T) range of 6-10GeV/c. For D-0 mesons in the high-p(T) range of 60-100GeV/c, a significantly smaller suppression is observed. The results are also compared to theoretical calculations. (C) 2018 The Author(s). Published by Elsevier B.V.
  • Wilkman, Olli; Gritsevich, Maria; Zubko, Nataliya; Peltoniemi, Jouni I.; Muinonen, Karri (2016)
    We have performed laboratory measurements of the bidirectional reflectance factor (BRF) of a sample of dark volcanic sand. The measurements were carried out with three different treatments of the sample to produce different porosity and roughness characteristics. We model the measured BRF with a semi-numerical scattering model for particulate media, meant especially for dark planetary regoliths. We compare the BRF in two different spectral bands, 500-600 nm and 800-900 nm. The particulate medium (PM). scattering model is found to fit the measured data well, with a phase function representing the differences between the spectral bands. The interpretation of the physical parameters of the PM model is qualitatively sound, but remains somewhat uncertain due in part to the difficulty of characterizing the measured sample. (C) 2016 Elsevier Ltd. All rights reserved.