From KEK Inter-University Research Institute Corporation: “SuperKEKB Phase 3 (Belle II Physics Run) Starts”

From KEK Inter-University Research Institute Corporation


On March 11th, 2019, Phase 3 operation of the SuperKEKB project began successfully, marking a major milestone in the development of Japan’s leading particle collider. This phase will be the physics run of the project, in which the Belle II experiment will start taking data with a fully instrumented detector.

The KEKB accelerator, operated from 1999 to 2010, currently holds the world record luminosity for an electron-positron collider. SuperKEKB, its successor, plans to reach a luminosity 40 times greater over its lifetime.

Belle II and SuperKEKB are poised to become the world’s first Super B factory facility. Belle II aims to accumulate 50 times more data than its predecessor, Belle, and to seek out new physics hidden in subatomic particles that could shed light on mysteries of the early universe.

Belle II KEK High Energy Accelerator Research Organization Tsukuba, Japan

The Belle experiment, which completed data taking in 2010, along with its competitor in the United States BaBar, demonstrated Charge-Parity Violation (CPV) in weak interactions of B mesons.



This discovery was explicitly recognized by the Nobel Foundation and resulted in the 2008 Nobel Prize for Physics being awarded to Professors Makoto Kobayashi and Toshihide Maskawa for their work developing the theory of CPV in weak interactions.

A major upgrade, the Belle II/SuperKEKB facility, began construction at the end of 2010. SuperKEKB will achieve its goal of 40 times KEKB’s luminosity by shrinking the beams to “nano-beam” size, at the collision point, 20 times smaller than the beam sizes achieved at KEKB while simultaneously doubling the beam currents. These changes will result in much larger quantities of data as well as greater beam backgrounds. Belle II was designed to handle these conditions.

In February 2016, Phase 1 commissioning of the SuperKEKB accelerator was successfully completed. Low-emittance Ampère-level beams were circulated in both rings, but no collisions were possible. This was followed by the installation of the superconducting final focus magnets and the Belle II outer detector. Phase 2, the pilot run of Belle II, began in March of 2018, with the first collisions recorded in the early hours of April 26th. Initial results from Phase 2 were shown at international conferences in 2018.

For Phase 3, installation of the full decay VerteX Detector (VXD) was completed. With this change, Belle II is now fully equipped and ready to take physics data.

See the full article here .


Please help promote STEM in your local schools.

Stem Education Coalition

KEK-Accelerator Laboratory

KEK, the High Energy Accelerator Research Organization, is one of the world’s leading accelerator science research laboratories, using high-energy particle beams and synchrotron light sources to probe the fundamental properties of matter. With state-of-the-art infrastructure, KEK is advancing our understanding of the universe that surrounds us, its mechanisms and their control. Our mission is:

• To make discoveries that address the most compelling questions in a wide range of fields, including particle physics, nuclear physics, materials science, and life science. We at KEK strive to make the most effective use of the funds entrusted by Japanese citizens for the benefit of all, by adding to knowledge and improving the technology that protects the environment and serves the economy, academia, and public health; and

• To act as an Inter-University Research Institute Corporation, a center of excellence that promotes academic research by fulfilling the needs of researchers in universities across the country and by cooperating extensively with researchers abroad; and

• To promote national and international collaborative research activities by providing advanced research facilities and opportunities. KEK is committed to be in the forefront of accelerator science in Asia-Oceania, and to cooperate closely with other institutions, especially with Asian laboratories.

Established in 1997 in a reorganization of the Institute of Nuclear Study, University of Tokyo (established in 1955), the National Laboratory for High Energy Physics (established in 1971), and the Meson Science Laboratory of the University of Tokyo (established in 1988), KEK serves as a center of excellence for domestic and foreign researchers, providing a wide variety of research opportunities. In addition to the activities at the Tsukuba Campus, KEK is now jointly operating a high-intensity proton accelerator facility (J-PARC) in Tokai village, together with the Japan Atomic Energy Agency (JAEA). Over 600 scientists, engineers, students and staff perform research activities on the Tsukuba and Tokai campuses. KEK attracts nearly 100,000 national and international researchers every year (total man-days), and provides excellent research facilities and opportunities to many students and post-doctoral fellows each year.