Construction Status of SuperKEKB Vacuum System

SuperKEKB, which is an upgrade of the KEKB B-factory (KEKB), is a next-generation high-luminosity electron-positron collider. The construction started on July 2010, and is still underway. In order to achieve its extra high performance (about 40 times the luminosity of the KEKB), many upgrades of the vacuum system must be performed. More than 1200 beam pipes are being replaced with new one with antechambers. To deal with a serious electron cloud issue expected in a positron ring, several types of countermeasures are adopted such as a titanium nitride (TiN) coating, solenoid field, clearing electrode and groove structure. More than 920 beam pipes had been delivered, and the pre-baking and TiN coating of them are finished in KEK so far. About 500 beam pipes are already installed in the SuperKEKB and the construction work of the vacuum system will be completed by the end of 2014.