After upgrade work, SuperKEKB, an electron-positron colliding accelerator located at the KEK laboratory in Tsukuba (Japan), has started operations. The accelerator is run by an international collaboration where researchers from the NSU Interdisciplinary Centre for Particle Physics and Astrophysics take an active part. Pavel Krokovny, a senior researcher of the Laboratory of Heavy Quark Physics and Hadrons shares some information about the experiment.
SuperKEKB represents a major upgrade from the previous KEKB accelerator where Bell experiment was carried out in 1999–2010. The project involves an upgraded version of the Belle detector, due to which the highest luminosity is going to be achieved. Before the upgrade, the KEK B Factory accelerator (KEKB), which was the predecessor to SuperKEKB, achieved the best beam collision performance in the world. However, after its operation terminated in June 2010, the KEKB accelerator group undertook the project of upgrading KEKB to SuperKEKB, for higher luminosity. Since then, the KEKB electron and positron rings, each of which has a circumference of 3,016 m, have been upgraded. The target luminosity has been set to 8×1035 cm−2s−1, about 50 times higher than that in the KEKB. Belle II construction is ongoing, with the current luminosity value of 2.108x1034 cm−2s−1 (in March, 2016).
“The experiment aims at studying parameters of CP asymmetry in B mesons. These mesons contain a massive particle called a bottom quark and a light antiquark. Using the increased luminosity, the upgraded collider (SuperKEKB) will enable to improve the accuracy of measurements and, probably, go beyond the Standard Model of particle physics,” says Pavel Krokovny.
A significant part of the collider was developed and manufactured in Novosibirsk, at the BINP SB RAS, including the 2 km of vacuum chamber for the positron ring and more than 200 powerful superconducting magnets.
As for the Belle II detector, which is also being upgraded, the group of researchers from Novosibirsk State University are improving the electromagnetic calorimeter which registers γ-quants and π-mesons.
The first physics run is scheduled to begin in 2017, when all the collider components have been upgraded and installed.