Determination of luminosity at CERN LHCb experiment

The experimental data from LHC beam-gas interactions at LHCb detector is used in this study. The interaction vertices are recorded by LHCb VELO sub-detector. Using these vertices, beam proton density and beam shape parameters are determined. Moreover, beam crossing angle and hourglass effects are studied. Finally a total luminosity calculation for year 2012 is carried out for LHCb detector by using the obtained parameters and by using the nominal LHC beam parameters. Results show that the beam proton distributions are rougly Gaussian. The beam emittances are determined to be around 50 𝜇𝑚 for x and y axes. The hourglas 𝛽∗ parameter is measured to be around 1 𝑚. The total luminosity in 2012 is determined to be 𝐿0=4.0 𝑓𝑏−1 at LHCb experiment.This value excludes the information that LHCb is using less luminosity from the delivered luminosity by LHC.