535 research outputs found
Statistical results from the Virginia Tech propagation experiment using the Olympus 12, 20, and 30 GHz satellite beacons
Virginia Tech has performed a comprehensive propagation experiment using the Olympus satellite beacons at 12.5, 19.77, and 29.66 GHz (which we refer to as 12, 20, and 30 GHz). Four receive terminals were designed and constructed, one terminal at each frequency plus a portable one with 20 and 30 GHz receivers for microscale and scintillation studies. Total power radiometers were included in each terminal in order to set the clear air reference level for each beacon and also to predict path attenuation. More details on the equipment and the experiment design are found elsewhere. Statistical results for one year of data collection were analyzed. In addition, the following studies were performed: a microdiversity experiment in which two closely spaced 20 GHz receivers were used; a comparison of total power and Dicke switched radiometer measurements, frequency scaling of scintillations, and adaptive power control algorithm development. Statistical results are reported
Search for a Signal on QCD Critical Point in Central Nucleus-Nucleus Collisions
We discuss that the QCD critical point could appear in central collisions in
percolation cluster. We suggest using the nuclear transparency effect and the
one of the light nuclear production to identify the critical point.Comment: To appear in the proceedings of the 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions (QM2008), Jaipur, India,
February 4-10, 200
Some Properties of the Central pi--Meson Carbon Interactions at 40 Gev/C
We discuss some properties of the central pi--meson carbon reactions at 40
GeV/c. While these results were obtained many years ago they have not been
explained completely. We attempt to interpret following: results regime change
on the behavior of some characteristics of the events as a function of the
centrality; anomaly peak on the angular distributions of the slow protons
emitted in these reactions; charge asymmetry on the pi--mesons production in
the back hemisphere in lcs.
Understanding of the results could help to explain the new ones coming from
the modern central experiments at high and ultrarelativistic energies.Comment: To appear in the proceedings of the 10th nternational Workshop on
Meson Production, Properties and Interaction (MESON 2008), Krakow, Poland, 6
- 10 June 2008. 4 pages and 4 figure
Event-by-event mean pT fluctuations in pp and PbāPb collisions at the LHC
Event-by-event fluctuations of the mean transverse momentum of charged particles produced in pp collisions at ās = 0.9, 2.76 and 7 TeV, and PbāPb collisions at āsNN = 2.76 TeV are studied as a function of the chargedparticle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations indicative of correlated particle emission are observed in all systems. The results in pp collisions show little dependence on collision energy. The Monte Carlo event generators PYTHIA and PHOJET are in qualitative agreement with the data. Peripheral PbāPb data exhibit a similar multiplicity dependence as that observed in pp. In central PbāPb, the results deviate from this trend, featuring a significant reduction of the fluctuation strength. The results in Pbā Pb are in qualitative agreement with previous measurements in AuāAu at lower collision energies and with expectations from models that incorporate collective phenomena
Charged jet cross sections and properties in proton-proton collisions at ās =7 TeV
The differential charged jet cross sections, jet fragmentation distributions, and jet shapes are measured in minimum bias proton-proton collisions at center-of-mass energy ās=7 TeV using the ALICE detector at the LHC. Jets are reconstructed from charged particle momenta in the midrapidity region using the sequential recombination kT and anti-kT as well as the SISCone jet finding algorithms with several resolution parameters in the range R Ā¼ 0.2ā0.6. Differential jet production cross sections measured with the three jet finders are in agreement in the transverse momentum (pT) interval 20 < pjet;ch T < 100 GeV=c. They are also consistent with prior measurements carried out at the LHC by the ATLAS Collaboration. The jet charged particle multiplicity rises monotonically with increasing jet pT, in qualitative agreement with prior observations at lower energies. The transverse profiles of leading jets are investigated using radial momentum density distributions as well as distributions of the average radius containing 80% (hR80i) of the reconstructed jet pT. The fragmentation of leading jets with R Ā¼ 0.4 using scaled pT spectra of the jet constituents is studied. The measurements are compared to model calculations from event generators (PYTHIA, PHOJET, HERWIG). The measured radial density distributions and hR80i distributions are well described by the PYTHIA model (tune Perugia-2011). The fragmentation distributions are better described by HERWIG
Suppression of Ī„(1S)at forward rapidity in PbāPb collisions at āsNN=2.76TeV
We report on the measurement of the inclusive (1S) production in Pb-Pb collisions at TeV carried out at forward rapidity ($2.
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