The JLC Accelerator Test Facility

highest-priority project for the future. Research and development toward the design of such a machine has occurred at KEK for more than a decade. Two major areas of current accelerator R&D at KEK include the technologies needed to generate high-quality beams in an injector complex and high-power microwave technology required for the main linear accelerators. Because its particle bunches encounter another bunch only once, a linear collider must achieve very narrow beams (several nanometers thick for the JLC) at the interaction point in order to provide sufficiently high luminosities required for the intended physics research. Therefore KEK physicists made key contributions to the Final Focus Test Beam project at SLAC, which succeeded in squeezing a 50 GeV electron beam down to a thickness of only 60 nanometers. Its advanced magnet system performed as designed by Katsunobu Oide, while Tsumoru Shintake pioneered a new technique to measure such narrow beams using laser interference fringes. One major improvement remaining to be demonstrated before a TeV linear collider can be built is the quality of the beams entering the NE OF THE MOST important experimental issues confronting physics today is the search for and study of the Higgs boson and other very heavy particles thought to be responsible for imbuing quarks, leptons, and gauge bosons with their various masses. This research can be done most effectively and efficiently at a high energy electron-positron collider. Thus the Japanese high energy physics community chose the construction of a large linear collider (called the Japan Linear Collider, or JLC) as its The JLC Accelerator Test Facility by SEIGI IWATA