Luminosity (scattering theory)

The luminosity is a term from the accelerator and high-energy physics, it describes the number of Teilchenbegegnungen per time and area. Thus, in addition to the indication of the collision energy, the efficiency of a particle accelerator marked.

Application

Using the luminosity, the expected event rate and the differential cross section of an experiment on a ring accelerator with two opposing particle beams can be determined:

The event rate, the number of expected events per time unit is a detector which is installed at a crossing point of the two particle beams in the accelerator.

Definition

The luminosity of a storage ring is clear from the numbers and the particles in the colliding packets ( engl. bunches ) and the number of bunches, which are placed at the repetition frequency of collision; the bunches have the cross-sectional area:

The luminosity is the same unit as the particle current density, namely, cm -2s -1.

If you want to examine a process as accurately as possible, that is, with high statistical significance, a high luminosity is necessary. This is dependent on the structure of the speed and quality of the particle beams in the accelerator.

Records

On a large LHC luminosity of about 1034 cm -2s -1 is to be achieved, while at the Tevatron last luminosities were obtained from about 4.1032 cm -2s -1. The current world record is held by electron / positron collider KEKB in Japan and is 2.11 · 1034 cm -2s -1 (7 June 2009).

However, the various accelerators are difficult to compare because of their different designs and types of accelerated particles: the world record for proton accelerators keeps the LHC with 7.73 · 1033 cm -2s -1 (Stand: February 10, 2014).