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Reconstruction du flux d'énergie et recherche de squarks et gluinos dans l'expérience D0

Abstract : The DO experiment is located at the Fermi National Accelerator Laboratory on the TeVatron proton-antiproton collider. The Run 11 has started in march 2001 after 5 years of shutdown and will allow DO extend its reach in squarks and gluinos searches, particles predicted by supersymmetry. In this work, 1 focussed on their decays that lead to signature with jets and missing transverse energy. But before the data taking started, I studied both software and hardware ways to improve the energy measurement which is crucial for jets and for missing transverse energy.
For each calorimeter channel, the physics and the calibration signal has been simulated based on a database of the 8 parameters that describe each channel. The parameters have been extracted from time reflectometry measurements. The calibration strategy can be defined using this simulation.
Energy deposits in the calorimeter has been clustered with ce11NN, at the cell level instead of the tower level. Efforts have been made to take advantage of the calorimeter granularity to aim at individual particles showers reconstruction. Ce11NN starts from the third floor which has a quadruple granularity compared to the other floors. The longitudinal information has been used to detect electromagnetic and hadronic showers overlaps.
Then, clusters and reconstructed tracks from the central detectors are combined and their energies compared. The better measurement is kept. Using this procedure allows to improve the reconstruction of each event energy flow.
The efficiency of the current calorimeter triggers has been determined. They has been used to perform a Monte Carlo search analysis of squarks and gluinos in the mSUGRA framework. The lower bound that DO will be able to put on squarks and gluinos masses with a 100 pb-1 integrated luminosity has been predicted. The use of the energy flow instead of standard reconstruction tools will be able to improve this lower limit.
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https://tel.archives-ouvertes.fr/tel-00002927
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Submitted on : Monday, June 2, 2003 - 3:58:21 PM
Last modification on : Wednesday, September 16, 2020 - 4:19:55 PM
Long-term archiving on: : Friday, April 2, 2010 - 6:43:50 PM

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  • HAL Id : tel-00002927, version 1

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LAL | CNRS | IN2P3

Citation

Mélissa Ridel. Reconstruction du flux d'énergie et recherche de squarks et gluinos dans l'expérience D0. Physique des Hautes Energies - Expérience [hep-ex]. Université Paris Sud - Paris XI, 2002. Français. ⟨tel-00002927⟩

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