KEK electron-positron linear accelerator

It is a multi-purpose linear accelerator (Linac) for supplying electron and positron beams to two rings of the KEKB collider and two light source rings PF/PF-AR simultaneously. Even one more ring, a positron damping ring, will be added soon for SuperKEKB. Linac is a high-energy linear accelerator with the total length 600 m and the maximum energy 10 billion electron volts 10GeV.

Purpose and Vision

The two rings of KEKB collided 3.5 GeV positrons and 8 GeV electrons to each other at its interaction point. The light sources PF and PF-AR need 2.5 GeV and 3.5 GeV electrons for injection, respectively. These beams with different charge, energy, and intensity are switched pulse-by-pulse at 50 Hz to perform top-up injection to each ring. Thus the beam currents in these rings are kept nearly constant during the experiment. By April 2009, the top-up injection was successfully performed for KEKB and PF, and PF-AR will join around 2016 with a new direct injection beam transport line.

SuperKEKB, which is under construction, requires significant upgrade of the Linac. While the beam energies will be changed to 4/7 GeV for positrons/electrons, the quality of the beams must be fairly high, which means small emittances with high bunch intensity. A new positron damping ring at 1.1 GeV will be also inserted in the middle of Linac. The beam performance will be achieved by a number of state-of-art technologies such as an innovative RF gun, positron target, special accelerating structures, precise control of the RF and the beam, etc.

Relates WEB sites

KEKB accelerator for researchers

Associated research groups

(The particle detector installed in the KEKB) Belle experiment