Luminosity determination in vs =7TeV proton Collisions Using the LHCf Front Counter at LHC

The LHCf experiment is dedicated to measure the particles emitted to forward region of proton-proton collisions at LHC. The physics goal is to afford the data for the calibration and improvement of the hadron interaction models. In this experiment, the luminosity that is necessary parameter to normalize the data has been determined with the counting rate of a detector called Front Counter and the conversion factor from the rate to the luminosity. During the LHCf physics operation at vs =7 TeV in 2010, the two calibrations of this conversion factor were carried out in 26th of April and 9th of May. This calibration is named vdM scan that is invented by S. van der Meer in 1969. The luminosity during the vdM scans were determined within 5%and 4%accuracy for April and May scan respectively. Finally, because the conversion factor is estimated within 5.5% accuracy, the luminosity determination in the LHCf experiment is also 5.5% accuracy.