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Mesure de la luminosité pour l'expérience H1

Abstract : At HERA, luminosity is determined on-line and bunch by bunch by measuring the bremsstrahlung spectrum from e-p collisions. The H1 collaboration has built a completely new luminosity system in order to sustain the harsh running conditions after the fourfold luminosity increase. Namely, the higher synchrotron radiation doses and the increased event pile-up have governed the design of the two major components, a radiation resistant quartz-fibre electro-magnetic calorimeter, and a fast read-out electronic with on-line energy histogramming at a rate of 500 kHz. The LLR group was in charge of the electronic and the on-line data analysis of the new luminosity system. In this thesis, I present analysis tools and methods to improve the precision of the luminosity measurement. The energy scale and acceptance calculation methods set out in this thesis permit these values to be determined every four minutes, to an accuracy of 0.5 parts per thousand for the energy scale and 2 parts per thousand for the acceptance. From these results, the degree of accuracy obtained on the luminosity measurement is between 6.5 and 9.5 parts per thousand. These results are currently undergoing validation, with the aim of becoming the standard H1 method.

I also studied quasi-elastic Compton events to cross-check the luminosity measurement using the 2003-2004 and 2005 data. Indeed, this process has a well calculable cross section and a clear experimental signature. The leptonic final state consists of a coplanar e-gamma system, both observable in the central H1 detector.
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Contributor : Thibault Frisson <>
Submitted on : Friday, August 3, 2007 - 3:14:11 PM
Last modification on : Thursday, March 5, 2020 - 6:25:27 PM
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  • HAL Id : tel-00166327, version 1



Thibault Frisson. Mesure de la luminosité pour l'expérience H1. Physique des Hautes Energies - Expérience [hep-ex]. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00166327⟩



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