Luminosity monitoring in ATLAS with MPX detectors

The ATLAS-MPX detectors are based on the Medipix2 silicon devices designed byCERN for the detection of multiple types of radiation. Sixteen such detectors were successfullyoperated in the ATLAS detector at the LHC and collected data independently ofthe ATLAS data-recording chain from 2008 to 2013. Each ATLAS-MPX detector providesseparate measurements of the bunch-integrated LHC luminosity. An internal consistencyfor luminosity monitoring of about 2% was demonstrated. In addition, the MPX devicesclose to the beam are sensitive enough to provide relative-luminosity measurements duringvan der Meer calibration scans, in a low-luminosity regime that lies below the sensitivityof the ATLAS calorimeter-based bunch-integrating luminometers. Preliminary results fromthese luminosity studies are presented for 2012 data taken at √s = 8 TeV proton-protoncollisions.© Copyright 2013 CERN for the benefit of the ATLAS Collaboration.Reproduction of this article or parts of it is allowed as specified in the CC-