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Development of a new Soft Muon Tagger for the Identification of b quarks, applied to a Top Quark Pair Production Cross Section Measurement, using the ATLAS Detector at CERN.
No full textThis thesis presents a study of a method for identifying b-jets by searching for “soft” muons produced within them. This method, a so-called Soft Muon Tagger, uses the quality of the match (Χ2match) between tracks left in the inner detector and the muon systems within the ATLAS detector to discriminate between muons within hadronic jets produced by the decay of b quarks, and those within light flavour jets.
The complete characteristics of the tagger are investigated in a detailed study on simulated data. The scale factors between the efficiency of the tagger in simulated and collision data, dependent on the kinematics of the tagged muon, are found using J/Ψ decays. These are used in a measurement of the top quark pair production cross section in collision data.
The measurement is performed on data taken during the 2011 run of the LHC, specifically in the lepton+jets top-antitop quark decay channel. A summary of this measurement is presented, and is found to be compatible with theoretical predictions for the cross section at a centre of mass energy of √s = 7 TeV, and with published ATLAS and CMS measurements using b-tagging in the lepton+jets channel. The measured cross section is:
σtt ̄ = 165 ± 2(stat.) ± 17(syst.) ± 3(lumi.) pb
The Χ2match-based soft muon tagger contributes a small b-tagging systematic uncertainty to the cross section measurement compared to measurements performed using lifetime based b-taggers, and has a good signal to background ratio
On the classifying space for the family of virtually cyclic subgroups for elementary amenable groups
No full textDeficits in volitional oculomotor control align with language status in autism spectrum disorders
No full textDeficits in volitional oculomotor control align with language status in autism spectrum disorder
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Share and share alike: Systems considerations for patron driven acquisition in a consortium
Get PDFPresentation given at the E-BASS25 End of Project Briefing on the library systems considerations of implementing consortial PDA
Enhancing multiphoton rates with quantum memories
No full textSingle photons are a vital resource for optical quantum information processing. Efficient and deterministic single photon sources do not yet exist, however. To date, experimental demonstrations of quantum processing primitives have been implemented using non-deterministic sources combined with heralding and/or postselection. Unfortunately, even for eight photons, the data rates are already so low as to make most experiments impracticable. It is well known that quantum memories, capable of storing photons until they are needed, are a potential solution to this `scaling catastrophe'. Here, we analyze in detail the benefits of quantum memories for producing multiphoton states, showing how the production rates can be enhanced by many orders of magnitude. We identify the quantity as the most important figure of merit in this connection, where and are the efficiency and time-bandwidth product of the memories, respectively
Curating Science in an Age of Empire: Kew's Museum of Economic Botany
No full textThis thesis considers the history and significance of the Museum of Economic Botany at the Royal Botanic Gardens, Kew, focussing especially on the period from its opening in 1847 to the eve of the First World War. Looking specifically at the Museum’s collection of wood specimens and artefacts, it seeks to understand the nature of economic botany during this period, and to evaluate the contribution made to the field by the Kew Museum. Through examination of the Museum’s practices, networks, spaces, and objects, it sets out to address the question: how do museums produce scientific knowledge? Part One sets the context. Chapter One provides a brief historical account of nineteenth-century economic botany and the Museum. Chapter Two offers a critical overview of literatures on Kew and economic botany; on the role of place in the production, circulation, and reception of scientific knowledge; and on the role of the public museum in Victorian science and culture. It also outlines the conceptual framework of the thesis. Chapter Three presents an account of the methodology and sources. Part Two highlights museum practices. Chapters Four to Six are devoted respectively to the practices of ‘exhibition’ (the spatialities, rhetorics, and rationalities of display); ‘instruction’ (the educational uses of museum objects); and ‘supply’ (the circulation of objects). Part Three turns to specific objects and their biographies. Chapters Seven and Eight trace respectively the production, circulation and reception of a totem pole from British Columbia and a timber trophy from Tasmania, to demonstrate how objects acquire diverse meanings in diverse contexts, and how they are used to impart meaning to particular sites. In conclusion, Chapter Nine reflects on the cumulative findings of the thesis and on its potential outcomes, and it looks beyond the thesis to recommend areas for future research and practice
Multi-photon quantum interference in a multi-port integrated photonic device
No full textIncreasing the complexity of quantum photonic devices is essential for many optical information processing applications to reach a regime beyond what can be classically simulated, and integrated photonics has emerged as a leading platform for achieving this. Here, we demonstrate three-photon quantum operation of an integrated device containing three coupled interferometers, eight spatial modes and many classical and nonclassical interferences. This represents a critical advance over previous complexities and the first on-chip nonclassical interference with more than two photonic inputs. We introduce a new scheme to verify quantum behaviour, using classically characterised device elements and hierarchies of photon correlation functions. We accurately predict the device's quantum behaviour and show operation inconsistent with both classical and bi-separable quantum models. Such methods for verifying multiphoton quantum behaviour are vital for achieving increased circuit complexity. Our experiment paves the way for the next generation of integrated photonic quantum simulation and computing devices
Multi-photon quantum interference in a multi-port integrated photonic device
Get PDFIncreasing the complexity of quantum photonic devices is essential for many optical information processing applications to reach a regime beyond what can be classically simulated, and integrated photonics has emerged as a leading platform for achieving this. Here, we demonstrate three-photon quantum operation of an integrated device containing three coupled interferometers, eight spatial modes and many classical and nonclassical interferences. This represents a critical advance over previous complexities and the first on-chip nonclassical interference with more than two photonic inputs. We introduce a new scheme to verify quantum behaviour, using classically characterised device elements and hierarchies of photon correlation functions. We accurately predict the device's quantum behaviour and show operation inconsistent with both classical and bi-separable quantum models. Such methods for verifying multiphoton quantum behaviour are vital for achieving increased circuit complexity. Our experiment paves the way for the next generation of integrated photonic quantum simulation and computing devices
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