Using Micromegas in ATLAS to Monitor the Luminosity

Five small prototype micromegas detectors were positioned in the ATLAS detector during LHC running at $\sqrt{s} = 8\, \mathrm{TeV}$. A $9\times 4.5\, \mathrm{cm^2}$ two-gap detector was placed in front of the electromagnetic calorimeter and four $9\times 10\, \mathrm{cm^2}$ detectors on the ATLAS Small Wheels, the first station of the forward muon spectrometer. The one attached to the calorimeter was exposed to interaction rates of about $70\,\mathrm{kHz/cm^2}$ at ATLAS luminosity $\mathcal{L}=5\times 10^{33}\,\mathrm{cm^{-2}s^{-1}}$ two orders of magnitude higher than the rates in the Small Wheel. We compare the currents drawn by the detector installed in front of the electromagnetic calorimeter with the luminosity measurement in ATLAS experiment.