Test Accelerator Facility for linear collider

The Japan National Laboratory for High-Energy Physics (KEK) has proposed building a Test Accelerator Facility (TAF) capable of producing a 2.5 GeV electron beam for stimulating R&D for a linear collider in the tera-electronvolt region. The TAF consists of a 1.5 GeV S-band linear accelerator, a 1.5 GeV damping ring, and a 1.0 GeV X-band linear accelerator. The TAF project will be carried forward in three phases. Through phase-I and phase-II, the S-band and X-band linacs will be constructed, and in phase-III, the damping ring will be completed. The construction of TAF phase-I has started, and the 0.2 GeV S-band injector linac is almost complete. The phase-I linac is composed of a 240 keV electron gun, subharmonic bunchers, prebunchers, and a traveling buncher followed by high-gradient accelerating structures. >