Electron-positron injector (LINAC)

Electron-positron injector (LINAC) is a linear accelerator that provides the positron beam and electron beam in two rings of SuperKEKB asymmetric collider for B physics currently under construction, and PF-AR and PF that are synchrotron radiation light sources.

Purpose and Vision

Two rings of SuperKEKB under construction, requires a beam of the following two.

Name of the ring Beam particle Energy
Electron ring (HER) Electron 7 billion electron volts (7GeV)
Positron ring (LER) Positron 4 billion electron volts (4GeV)

The research subject at this stage is to achieve a beam that is required in these new rings. Compared with the performance for the previous KEKB rings, much precise beam quality and much larger beam intensity are required to achieve 40-times higher collision luminosity. Development of Linac to respond to these requests is in progress now.


A device called a photo-cathode RF gun is being studied and developed to obtain a very narrow and intense electron beam. On the other hand, positrons are generated using a heavy metal target hit by electrons and are collected as much as possible using specially-designed pulsed magnetic coil and large aperture accelerating structures. Then, by passing it through a small circular accelerator called a damping ring a thick positron beam is squeezed to be thin.

Linac injects beams with very different characteristics into four storage rings at SuperKEKB, PF and PF-AR even integrating a newly-constructed damping ring. Those beams are switched pulse-by-pulse at 50Hz. In order to operate on such accelerator complex, fast and global control system is developed in a international collaboration as a new standard.

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