  The ATLAS-MPX detectors are based on the Medipix2 silicon devices designed by
CERN for the detection of multiple types of radiation. Sixteen such detectors
were successfully operated in the ATLAS detector at the LHC and collected data
independently of the ATLAS data-recording chain from 2008 to 2013. Each
ATLAS-MPX detector provides separate measurements of the bunch-integrated LHC
luminosity. An internal consistency for luminosity monitoring of about 2% was
demonstrated. In addition, the MPX devices close to the beam are sensitive
enough to provide relative-luminosity measurements during van der Meer
calibration scans, in a low-luminosity regime that lies below the sensitivity
of the ATLAS calorimeter-based bunch-integrating luminometers. Preliminary
results from these luminosity studies are presented for 2012 data taken at
sqrt(s)=8 TeV proton-proton collisions.
