The LHCB Online Luminosity Control and Monitoring

The online luminosity control consists of an automatic slow real-time feedback system controlled by specific LHCb software, which communicates directly with a\nLHC software application. The LHC application drives a set of corrector magnets to adjust the transversal beam overlap at the LHCb interaction point in order to keep the instantaneous luminosity aligned to the target luminosity provided by the experiment. It was proposed and tested first in July 2010, and it has been in routine operation during the first two years of physics luminosity data taking, 2011 and 2012. This paper describes the operational performance of the LHCb experiment and the LHC accelerator during the luminosity control of the experiment, the accounting of the recorded luminosity and dead time of the detector, and analyses the beam stability during the adjustment of the transverse beam overlap at the interaction point.