Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes ; are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ''van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas ; beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector ; the close proximity of the detector to the beams, ; allows beam parameters such as positions, angles ; widths to be determined. The results of the two methods have comparable precision ; are in good agreement. Combining the two methods, an overal precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented. © 2012 CERN.
Absolute luminosity measurements with the LHCb detector at the LHC
PAPPAGALLO, MARCO IGNAZIO;
2012-01-01
Abstract
Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes ; are valuable to quantify the performance of the accelerator. Using data taken in 2010, LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ''van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas ; beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector ; the close proximity of the detector to the beams, ; allows beam parameters such as positions, angles ; widths to be determined. The results of the two methods have comparable precision ; are in good agreement. Combining the two methods, an overal precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full 2010 data-taking period are presented. © 2012 CERN.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.