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

Search for vectorlike B quarks in events with one isolated lepton, missing transverse momentum, and jets at √s = 8 TeV with the ATLAS detector

A search has been performed for pair production of heavy vectorlike down-type (B) quarks. The analysis explores the lepton-plus-jets final state, characterized by events with one isolated charged lepton (electron or muon), significant missing transverse momentum, and multiple jets. One or more jets are required to be tagged as arising from b quarks, and at least one pair of jets must be tagged as arising from the hadronic decay of an electroweak boson. The analysis uses the full data sample of pp collisions recorded in 2012 by the ATLAS detector at the LHC, operating at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb −1 . No significant excess of events is observed above the expected background. Limits are set on vectorlike B production, as a function of the B branching ratios, assuming the allowable decay modes are B → Wt/Zb/Hb. In the chiral limit with a branching ratio of 100% for the decay B → Wt, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 810 GeV (760 GeV). In the case where the vectorlike B quark has branching ratio values corresponding to those of an SU(2) singlet state, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 640 GeV (505 GeV). The same analysis, when used to investigate pair production of a colored, charge 5/3 exotic fermion T 5/3 , with subsequent decay T 5/3 → Wt, sets an observed (expected) 95% C.L. lower limit on the T 5/3 mass of 840 GeV (780 GeV)

Phytoplasma diseases on major crops in Vietnam

The nested-PCR technique was applied to detect and identify phytoplasmas associated with major crops in Vietnam including sugarcane, cassava and longan. Phylogenetic analysis confirmed that phytoplasmas associated with the sugarcane grassy shoot and white leaf diseases belong to the rice yellow dwarf group (16SrXI). In cassava showing witches’ broom symptoms a mixed infection of phytoplasmas related to ‘Candidatus Phytoplasma asteris’ (group 16SrI) and ‘Ca. P. aurantifolia’ (group 16SrII) was detected. In samples showing longan witches’ broom disease three phytoplasmas including ‘Ca. P. aurantifolia’ (group 16SrII), elm yellows (group 16SrV) and “stolbur” (group 16SrXII) were identified

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

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

Evidence for Electroweak Production of W(+/-)W(+/-)jj in pp Collisions at root s=8 TeV with the ATLAS Detector

This Letter presents the first study of W(±)W(±)jj, same-electric-charge diboson production in association with two jets, using 20.3 fb(-1) of proton-proton collision data at sqrt[s] = 8  TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two reconstructed same-charge leptons (e(±)e(±), e(±)μ(±), and μ(±)μ(±)) and two or more jets are analyzed. Production cross sections are measured in two fiducial regions, with different sensitivities to the electroweak and strong production mechanisms. First evidence for W(±)W(±)jj production and electroweak-only W(±)W(±)jj production is observed with a significance of 4.5 and 3.6 standard deviations, respectively. The measured production cross sections are in agreement with standard model predictions. Limits at 95% confidence level are set on anomalous quartic gauge couplings

Physical activity during pregnancy through postpartum: A study of predictive and explanatory factors in a multi-ethnic population

The study objectives were to (a) describe steps and moderate-to-vigorous intensity physical activity (MVPA) from pregnancy and postpartum across ethnic groups, (b) test prognostic factors for early identification of pregnant women at risk of non-compliance with the guideline (=150 MVPA minutes/week), and (c) to explore the association between access to recreational areas and MVPA. Data originated from the Stork-Groruddalen Cohort Study (n=823). MVPA was monitored with a multi-sensor device in gestational week (GW) 15 and 28 and three months postpartum. Country of birth defined ethnicity. Data on access to recreational areas was obtained by geographic information systems and self-report. MVPA declined between GW 15 and 28, by which only 25% complied with the guideline. Four factors predicted guideline non-compliance (ethnic minority background, high body fat percentage, at least two previous births and few physically active friends). MVPA increased significantly for Western women between GW 28 and postpartum, while the increase was modest for ethnic minority women. Women with good access to recreational areas accumulated more MVPA minutes/day than women with limited access

Search for the lepton flavor violating decay Z \u2192 e\u3bc in pp collisions at 1as = 8 TeV with the ATLAS detector

The ATLAS detector at the Large Hadron Collider is used to search for the lepton flavor violating process Z \u2192 e\u3bc in pp collisions using 20.3 fb-1 of data collected at 1as = 8 TeV. An enhancement in the e\u3bc invariant mass spectrum is searched for at the Z-boson mass. The number of Z bosons produced in the data sample is estimated using events of similar topology, Z \u2192 ee and \u3bc\u3bc, significantly reducing the systematic uncertainty in the measurement. There is no evidence of an enhancement at the Z-boson mass, resulting in an upper limit on the branching fraction, B(Z \u2192 7.5 7 10.7 at the 95% confidence level