Operation and performance of the ATLAS semiconductor tracker

The semiconductor tracker is a silicon microstrip detector forming part of the inner tracking system of the ATLAS experiment at the LHC. The operation and performance of the semiconductor tracker during the first years of LHC running are described. More than 99% of the detector modules were operational during this period, with an average intrinsic hit efficiency of (99.74±0.04)%. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, δ-ray production and energy loss presented. The alignment of the detector is found to be stable at the few-micron level over long periods of time. Radiation damage measurements, which include the evolution of detector leakage currents, are found to be consistent with predictions and are used in the verification of radiation background simulations

Curriculum corruption? : On the place of subjects in secondary school curriculum making

The production of a W boson in association with a single charm quark is studied using 4.6 fb-1 of pp collision data at 1as = 7TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+-00.30 at Q2 = 1.9 GeV, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally the cross-section ratio \u3c3(W+ + c)/\u3c3(W- +c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s\u2013s quark asymmetry

Aspects of neutron-spin echo spectroscopy at pulsed sources

The integrated elliptic flow of charged particles produced in Pb+Pb collisions at (Formula presented.)\ua0TeV\ua0has been measured with the ATLAS detector using data collected at the Large Hadron Collider. The anisotropy parameter, v2, was measured in the pseudorapidity range |\u3b7| 642.5 with the event-plane method. In order to include tracks with very low transverse momentum pT, thus reducing the uncertainty in v2 integrated over pT, a 1 \u3bcb-1 data sample recorded without a magnetic field in the tracking detectors is used. The centrality dependence of the integrated v2 is compared to other measurements obtained with higher pT thresholds. The integrated elliptic flow is weakly decreasing with |\u3b7|. The integrated v2 transformed to the rest frame of one of the colliding nuclei is compared to the lower-energy RHIC data