SuperKEKB[1] is a particle collider located at KEK (High Energy Accelerator Research Organisation) in Tsukuba, Ibaraki Prefecture, Japan.
SuperKEKB collides electrons with positrons at the centre-of-momentum energy close to the mass of the Υ(4S) resonance making it a second-generation B-factory for the Belle II experiment.
[6] The accelerator will also perform short runs at energies of other Υ resonances, in order to obtain samples of other B mesons and baryons.
[1] The asymmetry in the beam energy provides a relativistic Lorentz boost to the B meson particles produced in the collision.
The accelerator has a circumference of 3016 m with four straight sections and experimental halls in the centre of each, named "Tsukuba", "Oho", "Fuji", and "Nikko".