Influence of e+e- pair creation in collision of laser and high energy photons for photon-photon colliders

We investigated the e+e- pair creation in the collision of laser and high energy photons in a photon-photon collider by a Monte Carlo simulation as well as by an analytic calculation. We found that the intensity near the high energy edge of the photon spectrum does not largely decrease above the threshold for e+e- pair creation. Moreover we found that the created pairs do not make a serious background to detectors. The possibility of using the JLC (Japan Linear Collider) at the center of mass energy ECM=0.5, 1.0 and 1.5 TeV as photon-photon colliders is considered. It is shown that above the threshold, the photon-photon colliders have the desired luminosity without background from the e+e- pairs. (orig.)