Preparations for Measurement of Electroweak Boson Production Cross-Sections using the Electron Decay Modes, with the Compact Muon Solenoid Detector

The Compact Muon Solenoid was designed to make discoveries at the TeV scale : to elucidate the nature of electroweak symmetry breaking and to search for physics beyond the Standard Model. For any such discovery to be credible, it must first be demonstrated that the CMS detector is understood. One mechanism to make this demonstration is to measure “standard candle” processes, such as W and Z production. This thesis describes preparations undertaken to make these measurements using the electron decay modes, with an integrated luminosity of 10 inverse picobarns of collision data. The energy resolution of the electromagnetic calorimeter was measured in test beam data. An improved method of deriving the optimised weights necessary for amplitude reconstruction is described. The measurement of electron charge using tracks is impaired by the electron showering in the tracker material. A novel charge measurement technique that is complementary to the existing method was assessed. Missing transverse energy is a powerful discriminating variable for the selection of W→eν events, however it is difficult to simulate accurately due to its global nature. The Ersatz Missing Energy method was developed to provide reliable and accurate descriptions of missing energy from data using readily reconstructible γ/Z → ee events. The method is described and evaluated. Finally, the measurement strategy for W and Z boson production cross-sections in early data is outlined and analysed using simulated data. Significant results can be obtained with only 10 inverse picobarns of integrated luminosity

Diagnosis by Documentary: Professional Responsibilities in Informal Encounters

Most work addressing clinical workers' professional responsibilities concerns the norms of conduct within established professional-patient relationships, but such responsibilities may extend beyond the clinical context. We explore health workers' professional responsibilities in such "informal" encounters through the example of a doctor witnessing the misdiagnosis and mistreatment of a serious long-term condition in a television documentary, arguing that neither internalist approaches to professional responsibility (such as virtue ethics or care ethics) nor externalist ones (such as the "social contract" model) provide sufficiently clear guidance in such situations. We propose that a mix of both approaches, emphasizing the noncomplacency and practical wisdom of virtue ethics, but grounding the normative authority of virtue in an external source, is able to engage with the health worker's responsibilities in such situations to the individual, the health care system, and the population at large

Response to Open Peer Commentaries on "Diagnosis By Television Documentary: Professional Responsibilities in Informal Encounters".

In presenting the situation of a health professional witnessing an instance of misdiagnosis and mistreatment in a television documentary, we hoped to stimulate discussion of the professional responsibilities of health workers in informal encounters in a rapidly changing environment comprising print, television, and more recently social media platforms. The commentaries on our article do not disappoint in this respect, providing insightful and sometimes challenging reactions to the position we outlined in response to our original case. In our reply here, we choose to focus on two themes running through all of the commentaries: (1) the distinction between axiological and deontic perspectives invoked by Salloch, and the open-endedness of the former that we see as crucial in addressing the constantly changing media landscape through which health workers may confront medical need; and (2) the role of institutional, structural, and social factors in constraining or enabling virtuous professional practice—suggesting perhaps a further need for health workers to take action directly against structural injustices that prevent them from fulfilling their professional responsibilities

Radiation hardness qualification of PbWO4 scintillation crystals for the CMS Electromagnetic Calorimeter

This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2010 IOPEnsuring the radiation hardness of PbWO4 crystals was one of the main priorities during the construction of the electromagnetic calorimeter of the CMS experiment at CERN. The production on an industrial scale of radiation hard crystals and their certification over a period of several years represented a difficult challenge both for CMS and for the crystal suppliers. The present article reviews the related scientific and technological problems encountered

Intercalibration of the barrel electromagnetic calorimeter of the CMS experiment at start-up

Calibration of the relative response of the individual channels of the barrel electromagnetic calorimeter of the CMS detector was accomplished, before installation, with cosmic ray muons and test beams. One fourth of the calorimeter was exposed to a beam of high energy electrons and the relative calibration of the channels, the intercalibration, was found to be reproducible to a precision of about 0.3%. Additionally, data were collected with cosmic rays for the entire ECAL barrel during the commissioning phase. By comparing the intercalibration constants obtained with the electron beam data with those from the cosmic ray data, it is demonstrated that the latter provide an intercalibration precision of 1.5% over most of the barrel ECAL. The best intercalibration precision is expected to come from the analysis of events collected in situ during the LHC operation. Using data collected with both electrons and pion beams, several aspects of the intercalibration procedures based on electrons or neutral pions were investigated

Search for squarks and gluinos with the ATLAS detector in final states with jets and missing transverse momentum using √s=8 TeV proton-proton collision data

A search for squarks and gluinos in final states containing high-p T jets, missing transverse momentum and no electrons or muons is presented. The data were recorded in 2012 by the ATLAS experiment in s√=8 TeV proton-proton collisions at the Large Hadron Collider, with a total integrated luminosity of 20.3 fb−1. Results are interpreted in a variety of simplified and specific supersymmetry-breaking models assuming that R-parity is conserved and that the lightest neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 1330 GeV for a simplified model incorporating only a gluino and the lightest neutralino. For a simplified model involving the strong production of first- and second-generation squarks, squark masses below 850 GeV (440 GeV) are excluded for a massless lightest neutralino, assuming mass degenerate (single light-flavour) squarks. In mSUGRA/CMSSM models with tan β = 30, A 0 = −2m 0 and μ > 0, squarks and gluinos of equal mass are excluded for masses below 1700 GeV. Additional limits are set for non-universal Higgs mass models with gaugino mediation and for simplified models involving the pair production of gluinos, each decaying to a top squark and a top quark, with the top squark decaying to a charm quark and a neutralino. These limits extend the region of supersymmetric parameter space excluded by previous searches with the ATLAS detector

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Evidence for the Higgs-boson Yukawa coupling to tau leptons with the ATLAS detector

Results of a search for H → τ τ decays are presented, based on the full set of proton-proton collision data recorded by the ATLAS experiment at the LHC during 2011 and 2012. The data correspond to integrated luminosities of 4.5 fb−1 and 20.3 fb−1 at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV respectively. All combinations of leptonic (τ → `νν¯ with ` = e, µ) and hadronic (τ → hadrons ν) tau decays are considered. An excess of events over the expected background from other Standard Model processes is found with an observed (expected) significance of 4.5 (3.4) standard deviations. This excess provides evidence for the direct coupling of the recently discovered Higgs boson to fermions. The measured signal strength, normalised to the Standard Model expectation, of µ = 1.43 +0.43 −0.37 is consistent with the predicted Yukawa coupling strength in the Standard Model

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns