Number 190 (Story #2), August 16, 1994 by Phillip F. Schewe and Ben Stein PHOTON-ELECTRON AND PHOTON-PHOTON COLLIDERS could be fashioned from linear electron-positron colliders. High-energy beams (up to hundreds of GeV) of photons would be produced by backscattering intense laser beams from oncoming bunches of electrons or positrons. Such high-energy photon beams, which could add a new avenue for studying the standard model of particle physics, are one ingredient in discussions now underway among US, European, and Japanese accelerator designers contemplating a next generation electron accelerator. Some of these ideas could be tried out on the present Stanford Linear Collider. (Physics Today, July; and CERN Courier, June.)