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Étude des performances du calorimètre à krypton liquide de l'expérience NA48 pour la mesure de Re(ε'/ε)

Abstract : The NA48 experiment aims to study direct CP violation in the neutral kaon system. The double ratio of neutral and charged two pion decays violating and conserving CP should be measured with an ultimate accuracy of approximately $0.1\%$. One of the main elements to reach this goal is the electromagnetic liquid krypton calorimeter which allows to identify neutral decays with a very good accuracy. One should therefore ensure that systematic effects are small. The performance of this calorimeter, mostly on the energy response, are studied with data taken in 1997. These studies are mostly done with the semileptonic $K_(e3)$ decays comparing the energy reconstructed in the calorimeter with the momentum given by the magnetic spectrometer. These data allow to constrain significantly the energy resolution and the non-linearity of the response as well as the geometry of the detector, and to optimise the calibration. The energy resolution achieved is better than $1\%$ for energies above $25$ $GeV$. This allows to reduce the neutral mode background at the level of $0.1\%$. The systematic uncertainties from the calorimeter on the double ratio measurement are estimated at $0.10\%$ for the 1997 data. This is significantly below the statistical error of $0.27\%$ for these data.
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Contributor : José Ocariz <>
Submitted on : Tuesday, January 20, 2004 - 6:23:02 PM
Last modification on : Wednesday, September 16, 2020 - 4:19:59 PM
Long-term archiving on: : Wednesday, September 12, 2012 - 12:45:09 PM

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  • HAL Id : tel-00004254, version 1

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José Ocariz. Étude des performances du calorimètre à krypton liquide de l'expérience NA48 pour la mesure de Re(ε'/ε). Physique des Hautes Energies - Expérience [hep-ex]. Université Paris Sud - Paris XI, 1999. Français. ⟨tel-00004254⟩

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