Concept of luminosity

The performance of particle colliders is usually quanti ed by the beam energy and the luminosity. We derive the expressions for the luminosity in case of bunched beams in terms of the beam parameters and the geometry. The implications of additional features such as crossing angle, offsets and hourglass effect on the luminosity are calculated. Important operational aspects like integrated luminosity, space and time structure of interactions etc. are discussed. The measurement of luminosity for e+e− as well as hadron colliders and the methods for the calibration of the absolute luminosity are described.