SuperKEKB accelerator kicks into new gear

Press release 2018年03月22日

KEK has begun a new stage of operation of the SuperKEKB electron-positron collider, with a brand new positron damping ring and the Belle II detector. Electron and positron beams will begin colliding soon for the first time in 8 years, since the previous KEKB collider ceased its operations in 2010.

On March 21, 2018, a beam of electrons was successfully stored in the main ring. A beam of positrons will be injected and stored around the beginning of the April, and then final accelerator tuning for beam collisions will begin. The first collisions of electrons and positrons are expected in the coming months.

This is the first step toward the SuperKEKB design luminosity1, which is a factor of 40 times higher than the current world record set by KEKB.

SuperKEKB, along with the Belle II detector, is a facility designed to search for New Physics beyond the Standard Model by measuring rare decays of elementary particles such as b quarks, c quarks, and tau leptons.

In contrast to the LHC at CERN in Geneva, Switzerland, which is the world’s highest energy hadron accelerator, SuperKEKB/Belle II located at KEK in Tsukuba, Japan is designed to have the world’s highest luminosity (a factor of 40 times higher than the earlier KEKB machine that holds many records for accelerator performance). Thus, SuperKEKB is the leading accelerator on the “luminosity frontier”.

The Belle II detector at SuperKEKB was designed and built by an international collaboration of over 750 physicists from 25 countries. This collaboration is working closely with SuperKEKB accelerator experts to optimize the accelerator performance and backgrounds.

Background information on the science goals of the SuperKEKB/Belle II facility is available on the Belle II public webpage :

Press contacts in Japan

  • Hikino Hajime, KEK PR Office,
  • Prof. Toru Iijima, Belle II Outreach coordinator, Nagoya University,

Additional images are available at the KEK webpage : KEK image archive - SuperKEKB/Belle II PressKit


    1. Luminosity is a measure of the rate or intensity of electron positron collisions

Related Images

Fig.1 Schematic drawing of the SuperKEKB/Belle II facility

Fig.2 The SuperKEKB accelerator and the Belle II detector at the interaction region