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T: Fachverband Teilchenphysik

T 15: Halbleiter: Laufende Experimente 1

T 15.1: Talk

Monday, March 9, 2015, 14:00–14:15, K.12.20 (K2)

Precision of MPX Detectors as LHC Luminosity Monitor — •Andre Sopczak¹, Babar Ali¹, Nedaa Asbah², Petr Benes¹, Benedikt Bergmann¹, Bartolomej Biskup¹, Michael Campbell³, Davide Caforio¹, Erik Heijne¹, Edward Kladiva⁴, Claude Leroy², Marzio Nessi³, Stanislav Pospisil¹, Frank Seifert¹, Jaroslav Solc¹, Paul Soueid², Michal Suk¹, Daniel Turecek¹, and Zdenek Vykydal¹ — ¹IEAP CTU in Prague — ²University of Montreal — ³CERN — ⁴IEP SAS Kosice

A network consisting of MPX detectors based on Medipix2 silicon pixel devices were originally adapted for measuring the composition and spectral characteristics of the radiation field in the ATLAS experiment and its surroundings. We demonstrate that the MPX network, which consists of 16 MPX detectors, is a self-contained luminosity monitor system. As the MPX detectors are collecting data independently of the ATLAS data-recording chain, they provide independent measurements of the bunch-integrated ATLAS/LHC luminosity. In particular, the MPX detectors close enough to the primary interaction point are used to perform van der Meer calibration scans with good precision. Results from the luminosity monitoring are presented for 2012 data taken at √s=8 TeV proton-proton collisions. The characteristics of the LHC luminosity reduction are studied and the effects of beam-beam (burn-off) and beam-gas (single bunch) interactions are evaluated. The variations of the MPX luminosity measurements around the fitted curve lead to a relative uncertainty on the luminosity measurement below 0.3% for one minute time intervals.