In scattering theory and accelerator physics, luminosity (L) is the ratio of the number of events detected (dN) in a certain period of time (dt) to the cross-section (σ):
It has the dimensions of events on time on area, and is usually expressed in the cgs units of cm<sup>âÂÂ2</sup>÷s<sup>âÂÂ1</sup> or the non-SI units of b<sup>âÂÂ1</sup>÷s<sup>âÂÂ1</sup>. In practice, L is dependent on the particle beam parameters, such as beam width and particle flow rate, as well as the target properties, such as target size and density.
A related quantity is integrated luminosity (L<sub>int</sub>), which is the integral of the luminosity with respect to time:
The luminosity and integrated luminosity are useful values to characterize the performance of a particle accelerator. In particular, all collider experiments aim to maximize their integrated luminosities, as the higher the integrated luminosity, the more data is available to analyze.
Here are a few examples of the luminosity of certain accelerators.