Belle II


The difference between matter and anti-matter is one of the most conspicous fundamental properties of the Universe. This difference is expected to be responsible for the existence of our World, and Mankind as a whole. In particle physics the difference between matter and anti-matter appears via the phenomenon of so-called CP-violation. The origin of this phenomenon is not yet completely understood. Therefore, the experimental study of this phenomenon has one of the highest priorities in High Energy Physics. The study of CP-violation is the main goal of the BELLE experiment operated at the KEKB accelerator in Japan. The precise test of the CP-violation pattern in mesons comprising b-quarks performed at BELLE and the competing experiment BaBar led to the Nobel Prize in physics in 2008.

CP-violation in mesons with b-quarks is expected to be sensitive to the existence of new heavier particles and/or new physics phenomena. Although the BELLE and BaBar experiments have shown no significant deviations from theory predictions, they still leave enough room for New Physics. To make a substantial step forward in the accuracy of measurements and put the existing theory (called Standard Model) to a challenging test, the luminosity of the KEKB accelerator will be increased dramatically (“Super B Factory”) and the BELLE detector will be upgraded to accommodate much higher channel occupancies.
In the upgraded BELLE detector, BELLE II, the detecting system responsible for muons and long-lived neutral kaons detection will be replaced by layers constructed from scintillator strips with WLS fibers read out by SiPMs. More than 20 thousands SiPMs will be used in this detector. The MEPhI, in collaboration with ITEP, is responsible for the development and construction of this detector. This joint group is supposed to become the core part of the proposed Project team. Experience gained by the Project team during the construction, commissioning and operation of this big detector will be invaluable for further applications of SiPMs. The analysis of collected data will lead either to discovery of New Physics beyond the Standard Model or to strong limits on the allowed parameter space.