1,787 research outputs found

    AFB(b) Status of Results

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    The status of results on forward-backward asymmetry in Z -> bbbar decays is reviewed. A comparison of LEP measurements, with emphasis on the final ALEPH measurement with leptons, and a critical discussion of average from heavy flavour electroweak combination is presented.Comment: 8 pages, 5 figures, to be published in Proceedings of "XXXVIIth Rencontres de Moriond - Electroweak Interactions and Unified Theories", Les Arcs, 9-16 March, 200

    The CMS Silicon Strip Tracker: from integration to start-up

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    The CMS Silicon Strip Tracker (SST) integration has been completed. After an extensive period of testing with cosmic muons the detector is ready for the final installation inside the CMS magnet. This paper will review the integration procedures and the tests completed to ensure that SST performs according to specifications

    Determination of the Lorentz Angle in Microstrip Silicon Detectors with Cosmic Muons

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    The microstrip silicon tracker of the CMS experiment will operate in a 4 T magnetic field in the harsh radiation environment of the Large Hadron Collider. The drift motion of the charge carriers will be therefore affected by the Lorentz force due to the high magnetic field. Furthermore, radiation damage will change in time the properties of this drift. In this note a method to measure the Lorentz angle from reconstructed tracks is presented and results obtained on Magnet Test and Cosmic Challenge data are compared to the values expected from a model, developed by the authors, which takes into account all the relevant parameters during the tracker lifetime (e.g. temperature and depletion voltage of the detectors)

    Model independent measurements of Standard Model cross sections with Domain Adaptation

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    With the ever growing amount of data collected by the ATLAS and CMS experiments at the CERN LHC, fiducial and differential measurements of the Higgs boson production cross section have become important tools to test the standard model predictions with an unprecedented level of precision, as well as seeking deviations that can manifest the presence of physics beyond the standard model. These measurements are in general designed for being easily comparable to any present or future theoretical prediction, and to achieve this goal it is important to keep the model dependence to a minimum. Nevertheless, the reduction of the model dependence usually comes at the expense of the measurement precision, preventing to exploit the full potential of the signal extraction procedure. In this paper a novel methodology based on the machine learning concept of domain adaptation is proposed, which allows using a complex deep neural network in the signal extraction procedure while ensuring a minimal dependence of the measurements on the theoretical modelling of the signal.Comment: 16 pages, 10 figure

    Three-dimensional muon imaging of cavities inside the Temperino mine (Italy)

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    : Muon radiography (muography) is an imaging technique based on atmospheric muon absorption in matter that allows to obtain two and three-dimensional images of internal details of hidden objects or structures. The technique relies on atmospheric muon flux measurements performed around and underneath the object under examination. It is a non-invasive and passive technique and thus can be thought of as a valid alternative to common prospecting techniques used in archaeological, geological and civil security fields. This paper describes muon radiography measurements, in the context of archaeological and geological studies carried out at the Temperino mine (LI, Tuscany, Italy), for the search and three-dimensional visualisation of cavities. This mine has been exploited since Etruscan times until recently (1973), and is now an active tourist attraction with public access to the tunnels. Apart from the archaeological interest, the importance of mapping the cavities within this mine lies in identifying the areas where the extraction ores were found and also in the safety issues arising from the tourist presence inside the mine. The three-dimensional imaging is achieved with two different algorithms: one involving a triangulation of two or more measurements at different locations; the other, an innovative technique used here for the first time, is based on the back-projections of reconstructed muon tracks. The latter requires only a single muographic data tacking and is to be preferred in applications where more than one site location can be difficult to access. Finally the quality of the three-dimensional muographic imaging was evaluated by comparing the results with the laser scan profiles obtained for some known cavities within the Temperino mine

    The 2003 Tracker Inner Barrel Beam Test

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    Before starting the CMS Silicon Strip Tracker (SST) mass production, where the quality control tests can only be done on single components, an extensive collection of activities aiming at validating the tracker system functionality has been performed. In this framework, a final component prototype of the Inner Barrel part (TIB) of the SST has been assembled and tested in the INFN laboratories and then moved to CERN to check its behaviour in a 25~ns LHC-like particle beam. A set of preproduction single-sided silicon microstrip modules was mounted on a mechanical structure very similar to a sector of the third layer of the TIB and read out using a system functionally identical to the final one. In this note the system setup configuration is fully described and the results of the test, concerning both detector performance and system characteristics, are presented and discussed

    Tracker Operation and Performance at the Magnet Test and Cosmic Challenge

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    During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented
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