References – CMSDAS Luminosity Short Exercise

Key Points

Introduction	Luminosity is a measure of how many collisions are delivered to and recorded by the detector. Instantaneous luminosity is usually expressed as the number of collisions per square centimeter per second. Integrated luminosity is the integral of instantaneous luminosity over time and is a measurement of data size. It is usually expressed in units of inverse cross section. Knowing the luminosity is important to determining and measuring accelerator and detector performance and operation. It is also an essential component for measuring cross sections and for setting limits on beyond-SM processes. Measurement of luminosity is done with muiltple systems in the CMS detector.
Using brilcalc	`brilcalc` is a command-line tool provided by the CMS BRIL group for querying luminosity information.
Normtags and Data Certification	Make sure to use a normtag when querying brilcalc for your analysis Data collected by CMS needs to be evaluated and a subset is certified as good quality data to be used for physics analysis

Fill: Increments once the LHC injects proton bunches into the LHC (more details: CERN Control Centre “From the LINAC to the LHC” (2014))
Run: Sub-section of a fill, increments each time the CMS central DAQ initates data taking
Lumi section: Sub-section of a run, defined as \(2^{18} \cdot \mathrm{orbits_{LHC}} = 2^{18} \cdot \frac{\mathrm{N_{bunches}}}{\mathcal{f}_{\mathrm{crossing}}} = 2^{18} \cdot \frac{3564}{40 \times 10^{6} \mathrm{Hz}} \approx 23.3570304 \mathrm{s}\)
Lumi nibble: Sub-section of a lumi section, defined as \(2^{12} \cdot \mathrm{orbits_{LHC}} \approx 0.3649536 \mathrm{s}\)