[en] An overview of the preliminary results of the top quark pair production cross section measurements at a center-of-mass energy of 1.96 TeV carried out by the CDF and D0 collaborations is presented. The data samples used for the analyses are collected in the current Tevatron run and correspond to an integrated luminosity from 360 pb^-1 up to 760 pb^-1

[en] We present a summary of the measurements of the top quark production and decay properties performed by the D0 experiment at the Fermilab Tevatron proton-antiproton collider at √s = 1.96 TeV using 1 fb^-1 of data. We discuss the first simultaneous measurements of the ratio of branching fractions. R = β(t → Wb)/β(t → Wq), with q being a d, s, or b quark, and the top quark pair production cross-section σ_tt, the first model-independent measurement of the helicity of W bosons produced in the top quark decays, and the first measurement of the integrated forward-backward charge asymmetry in the production of t t pairs.

[en] Preliminary results on the production cross section measurement at a center-of-mass energy of 1.96 TeV carried out by the CDF and DOe collaborations are presented. The data samples used for the analyses are collected in the current Tevatron run. (orig.)

[en] The preliminary results on the search for hard diffraction in p-bar p collisions with the D0 detector at Fermilab are presented. The presence of forward rapidity gaps is observed in events with high transverse momentum jet production at the center of mass energies 1800 and 630 GeV. The fraction of events with rapidity gaps is significantly higher than that expected due to multiplicity fluctuations and is consistent with predictions for hard single diffractive jet production. A class of events containing central di-jets and two forward rapidity gaps is observed at √s = 1800 GeV consistent with a hard double pomeron exchange event topology. (author)

[en] The preliminary results on the search for hard diffraction in pp collisions with the D0 detector at Fermilab are presented. The presence of forward rapidity gaps is observed in events with high transverse momentum jet production at the center of mass energies 1800 and 630 GeV. The fraction of events with rapidity gaps is significantly higher than that expected due to multiplicity fluctuations and is consistent with predictions for hard single diffractive jet production. A class of events containing central dijets and two forward rapidity gaps is observed at √s = 1800 GeV consistent with a hard double pomeron exchange event topology

[en] To achieve the smallest systematic uncertainty possible for the final, most precise single measurement of m_top with the DOe detector, we capitalise on the advantage of the initial state at the Fermilab's Tevatron collider over that provided by the CERN's LHC, which features notably higher initial state radiation rates. Moreover, due to the dominance of quark-antiquark annihilation in production of t anti t pairs at the Tevatron, the rate of initial state radiation can be extrapolated to final state radiation. We use unfolded distributions in φ^* at different Q², extracted from 7.3 fb^-1 of Z→ll events recorded by DOe, to evaluate systematic uncertainties on m_top from initial and final state radiation. φ^* is a novel topological variable, which offers superb sensitivity to the transverse momentum of the Z boson at the lower end of the spectrum compared to conventional observables. Besides the m_top measurement, our studies are relevant and beneficial for the majority of analyses in the top sector at the Tevatron, and can possibly be extended to the final state radiation at the LHC.

[en] The top quark mass is one of the fundamental parameters in the Standard Model. In the analysis presented here, the Neutrino Weighting approach is used to reconstruct top events in the dilepton channel. Assuming a neutrino rapidity distribution from Standard Model expectations and a top quark mass a priori, event weights can be obtained from comparing calculated and reconstructed missing transverse energy. A framework for the reconstruction of dileptonic top events in context of the ATLAS experiment and its implementation to extract the top quark mass is presented.

[en] The mass of the top quark is a free parameter of the Standard Model. Its precise measurement is highly relevant, as it may reveal valuable insights into the nature of electroweak symmetry breaking due to a Yukawa coupling of almost unity. We review the final steps towards the world's most precise single measurement of m_top, which we aim to perform in lepton+jets final states using 9.7 fb^-1 of data recorded by the DOe detector in p anti p collisions at √(s)=1.96 TeV. To extract m_top, we apply the so-called matrix element technique, which offers superior statistical sensitivity. We review the cutting-edge methods of numerical integration we employ to meet the computational challenges of this measurement. Furthermore, we summarise our studies which lead to an improved understanding of systematic uncertainties from higher-order contributions, hadronisation and underlying event, initial and final state radiation, the dependency of the jet energy scale on the jet flavour, and others, resulting in a combined systematic uncertainty of below 1 GeV.

[en] It has been shown that the neutron damage image as a divacancy D-cluster with a tetravacancy core adequately describes the neutron-induced effects observed in silicon grown by zone melting. Also it has been predicted that the decrease of total depletion voltage depends on the shrinkage of the outer part of space cluster charge when the doped impurity concentration exceeds the critical one. The expected value of the effect is determined by the factor ∼ [1-(r_n/r_cl)³]^-1, where r_cl and r_n are clusters radius and core radius, respectively

[en] Several different spare modules of the D0 experiment Silicon Microstrip Tracker (SMT) have been irradiated at the Fermilab Booster Radiation Damage Facility (RDF). The total dose received was 2.1 MRads with a proton flux of ∼3 · 10¹¹ p/cm² sec. The irradiation was carried out in steps of 0.3 or 0.6 MRad, with several days between the steps to allow for annealing and measurements. The leakage currents and depletion voltages of the devices increased with dose, as expected from bulk radiation damage. The double sided, double metal devices showed worse degradation than the less complex detectors