Measurement of event background fluctuations for charged particle jet reconstruction in Pb-Pb collisions at root s(NN)=2.76 TeV

The effect of event background fluctuations on charged particle jet reconstruction in Pb-Pb collisions at root s(NN) = 2.76 TeV has been measured with the ALICE experiment. The main sources of non-statistical fluctuations are characterized based purely on experimental data with an unbiased method, as well as by using single high p(t) particles and simulated jets embedded into real Pb-Pb events and reconstructed with the anti-k(t) jet finder. The influence of a low transverse momentum cut-off on particles used in the jet reconstruction is quantified by varying the minimum track p(t) between 0.15 GeV/c and 2 GeV/c. For embedded jets reconstructed from charged particles with p(t) > 0.15 GeV/c, the uncertainty in the reconstructed jet transverse momentum due to the heavy-ion background is measured to be 11.3 GeV/c (standard deviation) for the 10% most central Pb-Pb collisions, slightly larger than the value of 11.0 GeV/c measured using the unbiased method. For a higher particle transverse momentum threshold of 2 GeV/c, which will generate a stronger bias towards hard fragmentation in the jet finding process, the standard deviation of the fluctuations in the reconstructed jet transverse momentum is reduced to 4.8-5.0 GeV/c for the 10% most central events. A non-Gaussian tail of the momentum uncertainty is observed and its impact on the reconstructed jet spectrum is evaluated for varying particle momentum thresholds, by folding the measured fluctuations with steeply falling spectra.

A search for point sources of EeV neutrons

A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from -90 degrees to +15 degrees in declination using four different energy ranges above 1 EeV (10(18) eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.

LARGE-SCALE DISTRIBUTION OF ARRIVAL DIRECTIONS OF COSMIC RAYS DETECTED ABOVE 10(18) eV AT THE PIERRE AUGER OBSERVATORY

A thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10(18) eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 10(18) eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 10(18) eV from stationary Galactic sources densely distributed in the Galactic disk and predominantly emitting light particles in all directions.

J/psi Suppression at Forward Rapidity in Pb-Pb Collisions at root s(NN)=2.76 TeV

The ALICE experiment has measured the inclusive J/psi production in Pb-Pb collisions at root s(NN) = 2.76 TeV down to zero transverse momentum in the rapidity range 2.5 < y < 4. A suppression of the inclusive J/psi yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0%-80% most central collisions, is 0.545 +/- 0.032(stat) +/- 0.083dsyst_ and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/psi production from charm quarks in a deconfined partonic phase can describe our data.

J/psi production as a function of charged particle multiplicity in pp collisions at root s=7 TeV

The ALICE Collaboration reports the measurement of the relative J/psi yield as a function of charged particle pseudorapidity density dN(ch)/d eta in pp collisions at root s = 7 TeV at the LHC. J/psi particles are detected for p(t) > 0, in the rapidity interval vertical bar y vertical bar < 0.9 via decay into e(+)e(-), and in the interval 2.5 < y < 4.0 via decay into mu(+)/mu(-) pairs. An approximately linear increase of the J/psi yields normalized to their event average (dN(J/psi)/dy)/(dN(J/psi)/dy) with (dN(ch)/c eta)/(dN(ch)/d eta) is observed in both rapidity ranges, where dN(ch)/d eta is measured within vertical bar eta vertical bar < 1 and p(t) > 0. In the highest multiplicity interval with (dN(ch)/d eta)(bin)) = 24.1, corresponding to four times the minimum bias multiplicity density, an enhancement relative to the minimum bias J/psi yield by a factor of about 5 at 2.5 < y <4 (8 at vertical bar y vertical bar < 0.9) is observed. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

Light vector meson production in pp collisions at root s=7 TeV ALICE Collaboration

The ALICE experiment has measured low-mass dimuon production in pp collisions at root s = 7 TeV in the dimuon rapidity region 2.5 < y < 4. The observed dimuon mass spectrum is described as a superposition of resonance decays (eta, rho, omega, eta', phi) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for omega and phi are sigma(omega)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 5.28 +/- 0.54(stat) +/- 0.49(syst) mb and sigma(phi)(1 < p(t) < 5 GeV/c. 2.5 < y < 4) = 0.940 +/- 0.084(stat) +/- 0.076(syst) mb. The differential cross sections d(2)sigma/dy dp(t) are extracted as a function of p(t) for omega and phi. The ratio between the rho and omega cross section is obtained. Results for the phi are compared with other measurements at the same energy and with predictions by models. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.

Sinais clínicos e ocorrência de anticorpos anti-Chlamydophila abortus em ovinos de São Paulo e Minas Gerais

A Chlamydophila abortusi, anteriormente conhecida como Chlamydia psittaci sovovar 1, é uma bactéria Gram negativa, intracelular obrigatória. Esse micro-organismo é frequentemente encontrado em distúrbios reprodutivos em ovinos, bovinos e caprinos, sendo o aborto epizoótico dos bovinos e o aborto enzoótico dos ovinos e caprinos as manifestações mais importantes. Considerando-se o pouco material literário a respeito da clamidofilose no Brasil, a pesquisa teve como objetivo determinar a presença de anticorpos fixadores de complemento anti-Chlamydophila abortusi, correlacionando os resultados obtidos com achados no exame clínico e histórico dos animais, além de alterações nos índices zootécnicos, em especial na esfera reprodutiva, tais como alto índice de repetição de cio, número elevado de abortamentos, elevado número de natimortos, entre outros. Foram testadas para prova de fixação do complemento 220 amostras de soro de ovinos, de 26 propriedades, distribuídas em 19 municípios, com relato de manifestação reprodutiva, obtendo-se 19,55% (43/220) de testes positivos para Chlamydophila abortusi, com ocorrência de foco constatada de 61,53%. No geral, a titulação de anticorpos encontrada foi baixa, com título não superior a 64. A frequência de manifestação reprodutiva mais observada foi o aborto, representando 65,12% (28/43) do número total de animais soropositivos, seguido de repetição de cio juntamente com nascimento de cordeiro fraco, com frequência de 6,98% (3/43) e, por fim, morte neonatal com 4,65% (2/43), sendo que não houve associação significativa entre animais que foram positivos ao teste e a esses fatores.

Sinais clínicos e ocorrência de anticorpos anti-Chlamydophila abortus em ovinos de São Paulo e Minas Gerais

A Chlamydophila abortus, anteriormente conhecida como Chlamydia psittaci sovovar 1, é uma bactéria Gram negativa, intracelular obrigatória. Esse micro-organismo é frequentemente encontrado em distúrbios reprodutivos em ovinos, bovinos e caprinos, sendo o aborto epizoótico dos bovinos e o aborto enzoótico dos ovinos e caprinos as manifestações mais importantes. Considerando-se o pouco material literário a respeito da clamidofilose no Brasil, a pesquisa teve como objetivo determinar a presença de anticorpos fixadores de complemento anti-Chlamydophila abortus, correlacionando os resultados obtidos com achados no exame clínico e histórico dos animais, além de alterações nos índices zootécnicos, em especial na esfera reprodutiva, tais como alto índice de repetição de cio, número elevado de abortamentos, elevado número de natimortos, entre outros. Foram testadas para prova de fixação do complemento 220 amostras de soro de ovinos, de 26 propriedades, distribuídas em 19 municípios, com relato de manifestação reprodutiva, obtendo-se 19,55% (43/220) de testes positivos para Chlamydophila abortus, com ocorrência de foco constatada de 61,53%. No geral, a titulação de anticorpos encontrada foi baixa, com título não superior a 64. A frequência de manifestação reprodutiva mais observada foi o aborto, representando 65,12% (28/43) do número total de animais soropositivos, seguido de repetição de cio juntamente com nascimento de cordeiro fraco, com frequência de 6,98% (3/ 43) e, por fim, morte neonatal com 4,65% (2/43), sendo que não houve associação significativa entre animais que foram positivos ao teste e a esses fatores.

Reactive sputter magnetron reactor for preparation of thin films and simultaneous in-situ structural study by X-ray diffraction.

Reactive Sputter Magnetron (RSM) is a widely used technique to thin films growing of compounds both, in research laboratories and in industrial processes. The nature of the deposited compound will depend then on the nature of the magnetron target and the nature of the ions generated in the plasma. One important aspect of the problem is the knowledge of the evolution of the film during the process of growing itself. In this work, we present the design, construction of a chamber to be installed in the Huber goniometer in the XRD2 line of LNLS in Campinas, which allows in situ growing kinetic studies of thin films.