The electron-positron collider at KEK, KEKB, produces B meson and anti-B meson pairs. These mesons quickly decay into other particles. At the Belle detector (Belle experiment), the ways these particles decay (their decay modes) are studied. Due to the mass-production of B-mesons, this collider is sometimes called the B Factory.
B meson production begins with a 600-meter linear accelerator that produces and accelerates electrons and positrons. These beams of electrons and positrons circulate in KEKB's 3-kilometer circumference storage rings in opposite directions, and then collide on command. To store high-current beams, the KEKB team developed special accelerating cavities and vacuum chambers. KEKB currently holds the world record for luminosity (the collision rate of particles).
The Belle detector is located at the collision point on the north-east side of the KEKB rings. To detect the particle interactions, the Belle detector is composed of layers of high-resolution detector components, each with a different function. In 2001 it provided information about the difference in decay time distributions of B mesons and anti-B mesons, providing an experimental confirmation of the Kobayashi-Maskawa Theory of CP violation.
The Belle detector continues to discover many signs of new physics--physics beyond the Standard Model--by examining the decay processes of B mesons in detail. To further explore the new physics, the KEK B Factory plans to upgrade the colliders to increase their luminosity by a factor of 40.
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