KEKB (accelerator)
Coordinates: 36°9′17″N 140°4′19″E / 36.15472°N 140.07194°E KEKB is a particle accelerator used in the Belle experiment to study CP violation. KEKB is located at the KEK (High Energy Accelerator Research Organisation) in Tsukuba, Ibaraki Prefecture, Japan.
KEKB It is called a B-factory for its copious production of B-mesons which provide a golden mode to study and measure the CP violation due to its property of decaying into other lighter mesons. KEKB is basically an asymmetric electron–positron collider, with electrons having the energy of 8 GeV and positrons having the energy of 3.5 GeV, giving 10.58 GeV centre-of-mass energy, which is equal to the mass of the Υ(4S) meson.
There are basically two rings for accelerating electrons and positrons. The ring for electrons, having energy of 8 GeV, is called the high-energy ring (HER), while the ring for positrons, having energy of 3.5 GeV, is called low-energy ring (LER). The HER and LER are constructed side-by-side in the tunnel, which has been excavated already in the past for the former TRISTAN accelerator. TRISTAN was the first site to confirm vacuum polarization around an electron. The RF cavities in the HER use superconducting RF (SRF) technology, whereas the RF cavities in the LER use a normal conducting design denoted ARES. The circumference of each ring is 3016 m, having four straight sections. In the KEKB, there is only one interaction point in the "Tsukuba area", where the Belle experiment is located. The other areas (called "Fuji", "Nikko" and "Oho") are currently not actively used by an experiment.
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