Ultimate luminosities and energies of photon colliders

Abstract

A photon collider luminosity and its energy are determined by the parameters of an electron-electron linear collider (energy, power, beam emittances) and collision effects. The main collision effect is the coherent e+e- pair creation. At low energies (2E < 0.5 - 1 TeV) this process is suppressed due to repulsion of electron beams. In this region gamma-gamma luminosity above 10^{35} cm-2 s-1 is possible (10^{33} is sufficient). At higher energies the limited average beam power and coherent pair creation restrict the maximum energy of photon colliders (with sufficient luminosity) at 2E ~ 5 TeV. Obtaining high luminosities requires the development of new methods of production beams with low emittances such as a laser cooling.

Comments: 15 pages, Latex, 6 figures(eps), submitted to Proceedings of the Symposium on Future High Energy Colliders, ITP, UCSB, Santa Barbara, October 1996. AIP Press