Cite as: CMS Collaboration (2020). CMS detailed luminosity information, for 2011 CMS open data. CERN Open Data Portal. DOI:10.7483/OPENDATA.CMS.97U1.XZGT
CMS measures the luminosity using different luminometers (luminosity detectors) and algorithms. When available, the values taken with the Pixel Luminosity Telescope (pxl) should be used. If no pxl value is available for a particular lumi section, then the hfoc (Hadron Forward Zero Counting) value should be retrieved for that lumi section.
The integrated luminosity for validated runs and luminosity sections of all 2011 p-p data taking is available in the tables 2011lumi_pxl.txt and 2011lumi_hfoc.txt, for the respective luminometer. They include values for 2011 RunA and RunB.
In your estimate for the integrated luminosity, check for which runs the trigger you have selected is active and sum the values for those runs. The uncertainty in the luminosity measurement of 2011 data should be considered as 2.2% (reference CMS PAS SMP-12-008).
If you are using prescaled triggers, you can find the trigger prescale factors as shown in the trigger examples. The change of prescales (run, lumi section, index of prescales) is logged in the prescale2011.txt file from a previous version of this record.
Note that if there are orphan lumi sections – listed at the bottom of the lumi files as in json but not in results– for which there are neither pxl values nor hfoc values, they can be safely ignored. These lumi sections have no events as they correspond to the very end of runs for which the stable beam flag was not disabled yet during acquisition.
Additional information on how to extract luminosity values using the brilcalc tool can be found in the luminosity calculation guide.
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