PT Journal
AU LHCb Collaboration (Aaij, Rea
   Martinez-Vidal, F
   Oyanguren, A
   Ruiz Valls, P
   Sanchez Mayordomo, C
TI Precision luminosity measurements at LHCb
SO Journal of Instrumentation
JI J. Instrum.
PY 2014
BP P12005 - 91pp
VL 9
DI 10.1088/1748-0221/9/12/P12005
LA English
DE Pattern recognition; cluster finding; calibration and fitting methods; Instrumentation for particle accelerators and storage rings – high energy (linear accelerators; synchrotrons)
AB Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy root s. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for root s = 2.76, 7 and 8TeV (proton-proton collisions) and for root s(NN) = 5TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at root s = 8TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determines the luminosity with a precision of 1.16%. This represents the most precise luminosity measurement achieved so far at a bunched-beam hadron collider.
ER