KEK has two light source storage rings, PF and PF-AR. A very wide range of the radiated light, from visible light to X-ray, are provided for a variety of material science, biology, and life science.
Synchrotron radiation accelerator made first at KEK is called Photon Factory (PF). Beam energy is 2.5 GeV and the circumference of the ring is 187 m. This accelerator began operation in 1981 as the first dedicated synchrotron radiation accelerator in the world. It stores up to 450 mA in the ring and maintained nearly constant for days with a top-up injection. Another storage ring is called Photon Factory Advanced Ring (PF-AR). Beam energy is 6.5 GeV and the circumference of the ring is 377 m. PF-AR is a globally unique facility to utilize a light created by a single bunch in the ring. The top-up injection for PF-AR will start around 2016 with a new direct injection beam transport line from the Linac.