Abstract
The present work is related to LIDAR remote sensing of the atmosphere in the presence of cirrus clouds (CC) along the LIDAR line of sight (LOS), when the multiple-backscatter component of ...the LIDAR return may be essential. E. Eloranta has found analytical expressions of the multiple-backscatter components of different orders as containing the corresponding ratios of the multiple-to-single backscatter phase functions of the backward scattering medium. As a main purpose of this work, we estimated the above-mentioned ratios in cases of backscattering from air and CC, using accurate approximations of the single-scattering phase functions obtained by U. Wandinger. The results obtained show that the multiple-to-single backscatter phase function ratios for air are equal to unity, while for CCs they are quite near unity.
Abstract
Estimation is performed based on a theory developed by Eloranta of the double-scattering contribution to the LIDAR return from a multi-component atmosphere that may contain not only ...molecular (gaseous) and aerosol fractions, but other compact aerosol objects as well, such as cirrus clouds or Saharan dust layers. It is shown that the relative double-scattering component of the LIDAR return may be approximately considered as a sum of the independent relative contributions of each of the atmospheric components. Then, using appropriate models, the contribution of each component of interest is evaluated as a function of the altitude, taking into account the scattering properties of the medium under consideration, the angular divergence and the wavelength of the sensing laser beam, and the angle of view of the receiving optical system. The results obtained outline the cases when either the double scattering is negligible or corrections are necessary for the multiple scattering effects.
The Transition Radiation Detector (TRD) was designed and built to enhance the capabilities of the ALICE detector at the Large Hadron Collider (LHC). While aimed at providing electron identification ...and triggering, the TRD also contributes significantly to the track reconstruction and calibration in the central barrel of ALICE. In this paper the design, construction, operation, and performance of this detector are discussed. A pion rejection factor of up to 410 is achieved at a momentum of 1 GeV/ in p–Pb collisions and the resolution at high transverse momentum improves by about 40% when including the TRD information in track reconstruction. The triggering capability is demonstrated both for jet, light nuclei, and electron selection.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The ALICE Collaboration at the LHC has measured the J/ psi and psi ' photoproduction at mid-rapidity in ultra-peripheral ...Pb-Pb collisions at ... The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 mu b super(-1). The cross section for coherent and incoherent J/ psi production in the rapidity interval -0.9<y<0.9, are ... and ..., respectively. The results are compared to theoretical models for J/ psi production and the coherent cross section is found to be in good agreement with those models incorporating moderate nuclear gluon shadowing at Bjorken-x around 10 super(-3), such as EPS09 parametrization. In addition the cross section for the process gamma gamma arrow right e super(+) e super(-) has been measured and found to be in agreement with models implementing QED at leading order.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The production cross section of electrons from semileptonic decays of beauty hadrons was measured at mid-rapidity (| y | < 0.8) in the transverse momentum range 1 < p T < 8 GeV / c with the ALICE ...experiment at the CERN LHC in pp collisions at a center of mass energy s = 7 TeV using an integrated luminosity of 2.2 nb - 1 . Electrons from beauty hadron decays were selected based on the displacement of the decay vertex from the collision vertex. A perturbative QCD calculation agrees with the measurement within uncertainties. The data were extrapolated to the full phase space to determine the total cross section for the production of beauty quarkaantiquark pairs.
The inclusive transverse momentum (p T) distributions of primary charged particles are measured in the pseudo-rapidity range | IDT | 30 GeV / c . In peripheral collisions (70a80%), only moderate ...suppression (R A A = 0.6 a 0.7) and a weak p T dependence is observed. The measured nuclear modification factors are compared to other measurements and model calculations.
The elliptic, v 2 , triangular, v 3 , and quadrangular, v 4 , azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions, and (anti-)protons in PbaPb collisions at ...s NN = 2.76 TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range | IDT | 8 GeV / c . The small p T dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to p T = 8 GeV / c . The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least p T = 8 GeV / c indicating that the particle type dependence persists out to high p T .
The p T -differential inclusive production cross section of the prompt charm-strange meson D s + in the rapidity range | y | < 0.5 was measured in protonaproton collisions at s = 7 TeV at the LHC ...using the ALICE detector. The analysis was performed on a data sample of 2.98 X 10 8 events collected with a minimum-bias trigger. The corresponding integrated luminosity is L int = 4.8 nb - 1 . Reconstructing the decay D s + a I pi + , with I a K - K + , and its charge conjugate, about 480 D s +/- mesons were counted, after selection cuts, in the transverse momentum range 2 < p T < 12 GeV / c . The results are compared with predictions from models based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D 0 , D + , D a + and D s +) were determined both as a function of p T and integrated over p T after extrapolating to full p T range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e + e - , ep and pp interactions at various centre-of-mass energies.
The ALICE Collaboration has measured inclusive J / I production in pp collisions at a center-of-mass energy s = 2.76 TeV at the LHC. The results presented in this Letter refer to the rapidity ranges ...| y | < 0.9 and 2.5 < y < 4 and have been obtained by measuring the electron and muon pair decay channels, respectively. The integrated luminosities for the two channels are L int e = 1.1 nb - 1 and L int mu = 19.9 nb - 1 , and the corresponding signal statistics are N J / I e + e - = 59 +/- 14 and N J / I mu + mu - = 1364 +/- 53 . We present d I J / I / d y for the two rapidity regions under study and, for the forward-y range, d 2 I J / I / d y d p t in the transverse momentum domain 0 < p t < 8 GeV / c . The results are compared with previously published results at s = 7 TeV and with theoretical calculations.
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