Showing papers by "Paul Jackson published in 2010"
TL;DR: The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid, including supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors.
Abstract: The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.
1,514 citations
TL;DR: In this article, the authors used the ATLAS detector to detect dijet asymmetry in the collisions of lead ions at the Large Hadron Collider and found that the transverse energies of dijets in opposite hemispheres become systematically more unbalanced with increasing event centrality, leading to a large number of events which contain highly asymmetric di jets.
Abstract: By using the ATLAS detector, observations have been made of a centrality-dependent dijet asymmetry in the collisions of lead ions at the Large Hadron Collider. In a sample of lead-lead events with a per-nucleon center of mass energy of 2.76 TeV, selected with a minimum bias trigger, jets are reconstructed in fine-grained, longitudinally segmented electromagnetic and hadronic calorimeters. The transverse energies of dijets in opposite hemispheres are observed to become systematically more unbalanced with increasing event centrality leading to a large number of events which contain highly asymmetric dijets. This is the first observation of an enhancement of events with such large dijet asymmetries, not observed in proton-proton collisions, which may point to an interpretation in terms of strong jet energy loss in a hot, dense medium.
630 citations
TL;DR: In this article, the authors performed searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon with the entire data set of (963 +/- 7) x 10(6) tau decays collected by the BABAR detector near the Y(4S), Y(3S) and Y(2S) resonances.
Abstract: Searches for lepton-flavor-violating decays of a tau lepton to a lighter mass lepton and a photon have been performed with the entire data set of (963 +/- 7) x 10(6) tau decays collected by the BABAR detector near the Y(4S), Y(3S) and Y(2S) resonances. The searches yield no evidence of signals and we set upper limits on the branching fractions of B(tau(+/-) -> e(+/-)gamma) mu(+/-)gamma) < 4.4 X 10(-8) at 90% confidence level.
502 citations
TL;DR: An overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data and the determination of the global energy scale was performed with an uncertainty of 4%.
Abstract: The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experimental hall since its installation in late 2005. The readout, control and calibration systems have been fully operational since 2007 and the detector has successfully collected data from the LHC single beams in 2008 and first collisions in 2009. This paper gives an overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data. The detector operation status, noise characteristics and performance of the calibration systems are presented, as well as the validation of the timing and energy calibration carried out with minimum ionising cosmic ray muons data. The calibration systems’ precision is well below the design value of 1%. The determination of the global energy scale was performed with an uncertainty of 4%.
203 citations
TL;DR: The ATLAS Inner Detector as mentioned in this paper is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field, which was completed in 2008 and the detector took part in data-taking with single LHC beams and cosmic rays.
Abstract: The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1 +/- 0.9 mu m and a relative momentum resolution sigma (p) /p=(4.83 +/- 0.16)x10(-4) GeV(-1)xp (T) have been measured for high momentum tracks.
181 citations
TL;DR: The first measurements from proton-proton collisions recorded with the ATLAS detector at the LHC are presented in this paper, where the charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity, and the relationship between mean transversal momentum and charge multiplicity are measured for events with at least one charged particle in the kinematic range.
159 citations
TL;DR: A search for new heavy particles manifested as resonances in two-jet final states in 7 TeV proton-proton collisions by the LHC is presented, extending the reach of previous experiments.
Abstract: A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315 nb(-1) collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C. L. the q* mass interval 0: 30< m(q)*< 1:26 TeV, extending the reach of previous experiments.
137 citations
TL;DR: In this paper, the first measurements of the W and Z/gamma*-boson production cross sections in proton-proton collisions at 7 TeV are presented using data recorded by the ATLAS experiment at the LHC.
Abstract: First measurements of the W -> lnu and Z/gamma* -> ll (l = e, mu) production cross sections in proton-proton collisions at sqrt(s) = 7 TeV are presented using data recorded by the ATLAS experiment at the LHC. The results are based on 2250 W -> lnu and 179 Z/gamma* -> ll candidate events selected from a data set corresponding to an integrated luminosity of approximately 320 nb-1. The measured total W and Z/gamma*-boson production cross sections times the respective leptonic branching ratios for the combined electron and muon channels are $\stotW$ * BR(W -> lnu) = 9.96 +- 0.23(stat) +- 0.50(syst) +- 1.10(lumi) nb and $\stotZg$ * BR(Z/gamma* -> ll) = 0.82 +- 0.06(stat) +- 0.05(syst) +- 0.09(lumi) nb (within the invariant mass window 66 < m_ll < 116 GeV). The W/Z cross-section ratio is measured to be 11.7 +- 0.9(stat) +- 0.4(syst). In addition, measurements of the W+ and W- production cross sections and of the lepton charge asymmetry are reported. Theoretical predictions based on NNLO QCD calculations are found to agree with the measurements.
131 citations
TL;DR: In this article, an overview of the ATLAS liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events is presented.
Abstract: The ATLAS liquid argon calorimeter has been operating continuously since August 2006. At this time, only part of the calorimeter was readout, but since the beginning of 2008, all calorimeter cells have been connected to the ATLAS readout system in preparation for LHC collisions. This paper gives an overview of the liquid argon calorimeter performance measured in situ with random triggers, calibration data, cosmic muons, and LHC beam splash events. Results on the detector operation, timing performance, electronics noise, and gain stability are presented. High energy deposits from radiative cosmic muons and beam splash events allow to check the intrinsic constant term of the energy resolution. The uniformity of the electromagnetic barrel calorimeter response along eta (averaged over phi) is measured at the percent level using minimum ionizing cosmic muons. Finally, studies of electromagnetic showers from radiative muons have been used to cross-check the Monte Carlo simulation. The performance results obtained using the ATLAS readout, data acquisition, and reconstruction software indicate that the liquid argon calorimeter is well-prepared for collisions at the dawn of the LHC era.
123 citations
TL;DR: In this paper, the performance of the ATLAS detector in the first half a million minimum bias events of the LHC collision data was investigated at center-of-mass energies of 0.9 TeV and 2.36 TeV.
Abstract: More than half a million minimum-bias events of LHC collision data were collected by the ATLAS experiment in December 2009 at centre-of-mass energies of 0.9 TeV and 2.36 TeV. This paper reports on studies of the initial performance of the ATLAS detector from these data. Comparisons between data and Monte Carlo predictions are shown for distributions of several track- and calorimeter-based quantities. The good performance of the ATLAS detector in these first data gives confidence for successful running at higher energies.
78 citations
TL;DR: In this paper, the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs are discussed. And the results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy protonproton collisions.
Abstract: The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the calibration method of the detector response and of the alignment system, the track reconstruction efficiency and the momentum measurement. The results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy proton-proton collisions.
TL;DR: Breath analysis using an electronic nose showed promise in that there were significant differences in the smellprint of subjects with lung cancer compared with control subjects, and standardization of the technique will assist in improving the sensitivity and specificity of the method.
Abstract: Background. The measurement of gaseous compounds in exhaled breath, such as volatile organic compounds (VOCs), may provide a noninvasive technique for assessing lung pathology, some of which are associated with lung cancer (LC). VOC analysis is laborious while electronic noses are emerging as rapid detectors of an array of gaseous markers recognizing a characteristic “smellprint.” Objectives. To conduct a pilot breath analysis using an electronic nose to test the hypothesis that there would be significant differences in the smellprint patterns between newly diagnosed LC patients and control subjects. Methods. Eighty-nine subjects were recruited, consisting of nonsmokers (33), ex-smokers (11), smokers (18), patients with respiratory disorders (11), and LC patients (16). Subjects exhaled into gas-impermeable bags for offline eNose measurements with a six-channel electronic detection module ENS Mk 3 (E-Nose Pty, Sydney). The time-response curve from each channel was evaluated for four parameters: rate to peak height, peak height, rate to recovery, and area under the curve. Results. The results showed significant differences between lung cancer and control groups when measuring peak height in channel 1 (p = 0.025); rate to recovery in channel 3 (p = 0.045); and rate to peak height in channel 3 (p = 0.001). Conclusion. The results show promise in that there were significant differences in the smellprint of subjects with lung cancer compared with control subjects. Further standardization of the technique will assist in improving the sensitivity and specificity of the method, with potential to use the analysis in a number of diseases where characteristic signatures occur in the breath.
01 Oct 2010
TL;DR: A theoretically grounded, practical methodology for initial knowledge capture and ongoing maintenance of this knowledge using “Web 2.0” technologies is provided.
Abstract: Purpose – Knowledge capture from experts is important when that knowledge is of value, scarce, and threatened by loss, as is the case with the expected departure of “baby boomers” from the workforce This paper seeks to provide a theoretically grounded, practical methodology for initial knowledge capture and ongoing maintenance of this knowledge using “Web 20” technologiesDesign/methodology/approach – The paper used a participatory action research project in which a methodology was developed for the capture of knowledge from experts in an organization experiencing both knowledge loss and rapid growth The methodology used simple, affordable technologies such as digital cameras and digital editors, Wikis with a “semantic web” and social taggingFindings – The paper was able to integrate an initial knowledge capture into an ongoing cycle of knowledge organizing, sharing and maintenance It was found that, whilst it is an economical and appropriate solution to problems of knowledge loss and knowledge shari
Journal Article•
TL;DR: In this article, the ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons, and the drift time of the ionisation electrons is measured and used to assess the intrinsic uniformity of the CALorimeter gaps and estimate its impact on the constant term of the energy resolution.
Abstract: The ionization signals in the liquid argon of the ATLAS electromagnetic calorimeter are studied in detail using cosmic muons. In particular, the drift time of the ionization electrons is measured and used to assess the intrinsic uniformity of the calorimeter gaps and estimate its impact on the constant term of the energy resolution. The drift times of electrons in the cells of the second layer of the calorimeter are uniform at the level of 1.3% in the barrel and 2.8% in the endcaps. This leads to an estimated contribution to the constant term of (0.29(-0.04)(+0.05))% in the barrel and (0.54(-0.04)(+0.06))% in the endcaps. The same data are used to measure the drift velocity of ionization electrons in liquid argon, which is found to be 4.61 +/- 0.07 mm/mu s at 88.5 K and 1 kV/mm.
Book•
17 Nov 2010
TL;DR: In this paper, the development of the concept of SSR in Sierra Leone and its impact on international policy making on SSR is discussed. But the authors focus on the period from 2002 to the end of the conflict.
Abstract: Introduction How did SSR in Sierra Leone Impact on International Policy Making on SSR? Security and Sierra Leone Up Until the End of the Conflict The Development of the Concept of SSR 2002-2005 Consolidation and Development, 2005-2007 Cross-cutting Themes Throughout the Period in Sierra Leone and Beyond Conclusions
TL;DR: In this article, the branching fractions of neutral and charged B meson decays to final states containing a K_1(1270) or K_ 1(1400) meson and a charged pion.
Abstract: We report measurements of the branching fractions of neutral and charged B meson decays to final states containing a K_1(1270) or K_1(1400) meson and a charged pion. The data, collected with the BABAR detector at the SLAC National Accelerator Laboratory, correspond to 454×10^6 BB pairs produced in e^+e^- annihilation. We measure the branching fractions B(B^0→K_1(1270)^+π-+K_1(1400)^+π-)=3.1_(-0.7)^(+0.8)×10^(-5) and B(B^+→K_1(1270)^0π^++K_1(1400)^0π^+)=2.9_(-1.7)^(+2.9)×10^(-5) (<8.2×10^(-5) at 90% confidence level), where the errors are statistical and systematic combined. The B^0 decay mode is observed with a significance of 7.5σ, while a significance of 3.2σ is obtained for the B^+ decay mode. Based on these results, we estimate the weak phase α=(79±7±11)° from the time-dependent CP asymmetries in B^0→a1(1260)^±π^∓ decays.
TL;DR: A survey of the relationship between British fascism and religion in both the interwar and postwar periods is presented in this paper, which highlights how various fascists organisations and ideologues have developed religious dimensions to their politics.
Abstract: This article surveys the relationship between British fascism and religion in both the interwar and postwar periods. After identifying a fascist tradition in Britain by drawing on the theories of ‘new consensus’ scholars, it highlights how various fascists organisations and ideologues have developed religious dimensions to their politics. From the British Fascists who presented themselves as defenders of Christianity, to the Imperial Fascist League which used religion to legitimise its anti-Semitism, to Oswald Mosey who developed his own political religion, interwar fascists are revealed as figures who used a spiritual politics as a marker of national identity. Postwar fascists such as John Tyndall and Colin Jordan are shown to be more critical of religion. Meanwhile, the British National Party has developed a new politics around faith and Christian identity, which is also now steeped in Islamopobia. Therefore, the article concludes that the relationship between British fascism and religion has a complex history and is highly relevant contemporary trends in British fascism.
Book•
01 Jan 2010
TL;DR: Introduction Web 2.0 tools and context The modern business environment From purpose to space From space to function From function to use Putting it together.
Abstract: Whilst enterprise technology departments have been steadily building their information and knowledge management portfolios, the Internet has generated new sets of tools and capabilities which provide opportunities and challenges for improving and enriching knowledge work. This book fills the gap between strategy and technology by focussing upon the functional capabilities of Web 2.0 in corporate environments and matching these to specific types of information requirement and behaviour. It takes a resource based view of the firm: why and how can the knowledge capabilities and information assets of organisations be better leveraged using Web 2.0 tools?Identifying the underlying benefits requires the use of frameworks beyond profitability and cost control. Some of these perspectives are not in the usual business vocabulary, but when applied, demonstrate the role that can be played by Web 2.0, how to manage towards these and how to assess success. Transactive memory systems, social uncertainty, identity theory, network dynamics, complexity theory, organisational memory and the demographics of inter- generational change are not part of normal business parlance but can be used to clarify Web 2.0 application and potentiality.Written by a well-respected practitioner and academicDraws on the author?s practical experience as a technology developer, designer, senior manager and researcherProvides approaches to understanding and tackling real-world problems
Posted Content•
TL;DR: This paper examines how the use of Web 2.0 tools (such as Wikis, Blogs, Social Networking) might provide a digital foundation for a Transactive Memory System (TMS), constituting essentially a knowledge directory which can be used to locate knowledge seekers or advise them of content they may be interested in.
Abstract: In this paper we examine how the use of Web 2.0 tools (such as Wikis, Blogs, Social Networking) might provide a digital foundation for a Transactive Memory System (TMS). TMS facilitate knowledge sharing and retrieval processes in groups by the use of a well-maintained knowledge directory. The theory of TMS explains how it is that a group appears to have a "group mind" and research shows that a well functioning TMS improves group performance. Web 2.0 software embeds data about authors, interested parties and related information into the content created in these tools, constituting essentially a knowledge directory which can be used to locate knowledge seekers or advise them of content they may be interested in. Consequently, the use of Web 2.0 tools may improve knowledge absorption and utilisation by supporting TMS. This is a conceptual paper, which seeks to provide a link between Web 2.0 and TMS and, by implication, enhancement in the functioning of groups and organisations.