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 /ja/activity/accl/KEKB.html
KEKB accelerator for researchers

Associated research groups

(The particle detector installed in the KEKB) Belle experiment