Search for dark matter and large extra dimensions in monojet events in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Study of the inclusive production of charged pions, kaons, and protons in pp collisions at root s=0.9, 2.76, and 7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of jet fragmentation into charged particles in pp and PbPb collisions at root s(NN)=2.76 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ratios of dijet production cross sections as a function of the absolute difference in rapidity between jets in proton-proton collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Measurement of the relative prompt production rate of chi(c2) and chi(c1) in pp collisions at root s=7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Indium tin oxide films prepared via wet chemical route

In this work, indium tin oxide (ITO) films were prepared using a wet chemical route, the Pechini method. This consists of a polyesterification reaction between an alpha-hydroxicarboxylate complex (indium citrate and tin citrate) with a polyalcohol (ethylene glycol) followed by a post annealing at 500 degrees C. A 10 at.% of doping of Sn4+ ions into an In2O3 matrix was successfully achieved through this method. In order to characterize the structure, the morphology as well as the optical and electrical properties of the produced ITO films, they were analyzed using different experimental techniques. The obtained films are highly transparent, exhibiting transmittance of about 85% at 550 nm. They are crystalline with a preferred orientation of [222]. Microscopy discloses that the films are composed of grains of 30 nm average size and 0.63 nm RMS roughness. The films' measured resistivity, mobility and charge carrier concentration were 5.8 x 10(-3) Omega cm, 2.9 cm(2)/V s and -3.5 x 10(20)/cm(3), respectively. While the low mobility value can be related to the small grain size, the charge carrier concentration value can be explained in terms of the high oxygen concentration level resulting from the thermal treatment process performed in air. The experimental conditions are being refined to improve the electrical characteristics of the films while good optical, chemical, structural and morphological qualities already achieved are maintained. (C) 2007 Elsevier B.V. All rights reserved.

Use of strontium in the activation of bovine oocytes reconstructed by somatic cell nuclear transfer

As an important step in the nuclear transfer (NT) procedure, we evaluated the effect of three different treatments for oocyte activation on the in vitro and in vivo developmental capacity of bovine reconstructed embryos: (1) strontium, which has been successfully used in mice but not yet tested in cattle; (2) ionomycin and 6-dimethylammopurine (6-DMAP), a standard treatment used in cattle; (3) ionomycin and strontium, in place of 6-DMAP. As regards NT blastocyst development, no difference was observed when strontium (20.1%) or ionomycin/6-DMAP (14.4%) were used. However, when 6-DMAP was substituted by strontium (3), the blastocyst rate (34.8%) was superior to that in the other activation groups (p < 0.05). Results of in vivo development showed the possibility of pregnancies when NT embryos activated in strontium were transferred to recipient cows (16.6%). A live female calf was obtained when ionomycin/strontium were used, but it died 30 days after birth. Our findings show that strontium can be used as an activation agent in bovine cloning procedures and that activation with a combination of strontium and ionomycin increased the in vitro developmental capacity of reconstructed embryos. This is the first report of a calf produced by adult somatic cell NT in Latin America.

Single top quark at future hadron colliders: Complete signal and background study

We perform a detailed theoretical study including decays and jet fragmentation of all the important modes of single top quark production and all the basic background processes at the upgraded Fermilab Tevatron and CERN LHC colliders. Special attention is paid to the complete tree level calculation of the QCD fake background which was not considered in previous studies. An analysis of the various kinematical distributions for the signal and backgrounds allow us to work out a set of cuts for an efficient background suppression and extraction of the signal. It is shown that the signal to background ratio after optimized cuts could reach about 0.4 at the Tevatron and 1 at the LHC. The remaining after cuts signal rate at the LHC for the lepton+jets signature is expected to be about 6.1 pb and will be enough to study single top quark physics even during LHC operation at a low luminosity. ©1999 The American Physical Society.

R-parity-violating signals for chargino production at LEP II

We study chargino pair production at LEP II in supersymmetric models with spontaneously broken R-parity. We perform signal and background analyses, showing that a large region of the parameter space of these models can be probed through chargino searches at LEP II. In particular, we determine the attainable limits on the chargino mass as a function of the magnitude of the effective bilinear R-parity violation parameter ∈, demonstrating that LEP II is able to unravel the existence of charginos with masses almost up to their kinematical limit even in the case of R-parity violation. This requires the study of several final state topologies since the usual MSSM chargino signature is recovered as ∈ → 0. Moreover, for sufficiently large ∈ values, for which the chargino decay mode χ ± → τ ± J dominates, we find through a dedicated Monte Carlo analysis that the χ ± mass bounds are again very close to the kinematic limit. Our results establish the robustness of the chargino mass limit, in the sense that it is basically model-independent. They also show that LEP II can establish the existence of spontaneous R-parity violation in a large region of parameter space should charginos be produced. © 1999 Elsevier Science B.V.

Measurement of the pp(-)-> W gamma plus X cross section at root s=1.96 TeV and WW gamma anomalous coupling limits

The WWγ triple gauge boson coupling parameters are studied using pp̄rarr; νγ+X(=e,μ) events at s=1.96 TeV. The data were collected with the D0 detector from an integrated luminosity of 162pb-1 delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for pp̄→W(γ)+X→ νγ+X with ETγ>8 GeV and ΔR γ> 0.7 is 14.8±1.6(stat)±1.0(syst) ±1.0(lum)pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88<Δκγ<0.96 and -0. 20<λγ<0.20. © 2005 The American Physical Society.

Calcium modified lead titanate/poly-ether-ether-ketone composite for acoustic emission sensors

Composites made of calcium modified lead titanate ceramic powder and poly (ether-ether-ketone) high performance polymer matrix were prepared in the film form using a hot press. The acoustic and electromechanical properties of the composites have been determined using the ultrasonic immersion technique and piezoelectric spectroscopy, respectively. The composite film with 60 - 40 vol.% PTCa/PEEK was tested as acoustic emission detector. Preliminary results shown that the piezo composite can be used as sensor to evaluate the behavior of materials.

Arranjo espacial de plantas de milho em sistema plantio direto

The interaction of management practices that increases plant density and reduces row spacing by spatial arrangement, if well planned, can be an excellent opportunity for the producers to increase their profitability. The objective of this study was to evaluate the variation effects of plant spatial distribution in two maize hybrids cultivated in a no-tillage system on the production components. The study was conducted in the CECA/UFAL. The treatments consisted of the cultivation of two hybrids of maize, FORT and AGN 30A00, in row spacings of 0.80 and 0.40 m and with plant densities of 60,000 and 70,000 plants ha -1. The statistical design was randomized blocks in a 2 x 2 x 2 factorial scheme, with three replications. From the results obtained, it may be concluded that neither the row spacing reduction nor plant density increase, as isolated practices, do not increase grain yield in the tested cultivars. The association of the reduction in row spacing and increase in plant population resulted in significant gain in grain productivity for the hybrid FORT.

Commissioning of the CMS experiment and the cosmic run at four tesla

The CMS Collaboration conducted a month-long data-taking exercise known as the Cosmic Run At Four Tesla in late 2008 in order to complete the commissioning of the experiment for extended operation. The operational lessons resulting from this exercise were addressed in the subsequent shutdown to better prepare CMS for LHC beams in 2009. The cosmic data collected have been invaluable to study the performance of the detectors, to commission the alignment and calibration techniques, and to make several cosmic ray measurements. The experimental setup, conditions, and principal achievements from this data-taking exercise are described along with a review of the preceding integration activities. © 2010 IOP Publishing Ltd and SISSA.

Fine synchronization of the CMS muon drift-tube local trigger using cosmic rays

The CMS experiment uses self-triggering arrays of drift tubes in the barrel muon trigger to perform the identification of the correct bunch crossing. The identification is unique only if the trigger chain is correctly synchronized. In this paper, the synchronization performed during an extended cosmic ray run is described and the results are reported. The random arrival time of cosmic ray muons allowed several synchronization aspects to be studied and a simple method for the fine synchronization of the Drift Tube Local Trigger at LHC to be developed. © 2010 IOP Publishing Ltd and SISSA.

Time reconstruction and performance of the CMS electromagnetic calorimeter

The resolution and the linearity of time measurements made with the CMS electromagnetic calorimeter are studied with samples of data from test beam electrons, cosmic rays, and beam-produced muons. The resulting time resolution measured by lead tungstate crystals is better than 100 ps for energy deposits larger than 10 GeV. Crystal-to-crystal synchronization with a precision of 500 ps is performed using muons produced with the first LHC beams in 2008. © 2010 IOP Publishing Ltd and SISSA.