First turns and successful storage of beams in the SuperKEKB electron and positron rings

After five years of large-scale upgrade work an electron-positron colliding accelerator has started test operations at KEK in Japan. Its name is SuperKEKB and it is the successor of KEKB accelerator.

On February 10, SuperKEKB succeeded in circulating and storing a positron beam in the positron ring, and on February 26, succeeded in circulating and storing an electron beam in the electron ring as well. Machine tuning will continue until the end of June 2016, followed by installation of the Belle II detector upgrade and new superconducting electromagnets for the final focus at the collision point. Machine tuning will then be carried out to achieve collisions of the electron and positron beams. SuperKEKB has adopted and will realize for the first time a nano-beam large-angle crossing collision scheme, with the beam size at the collision point reduced to 1/20th of the beam size of KEKB. The stored beam current will also be increased to twice that of KEKB, with the final aim of achieving a collision performance 40 times higher than that of KEKB.

The rate of collisions produced by SuperKEKB will be several tens of times larger than that of KEKB. The aim is to pursue the mystery of the disappearance of anti-matter during the early, developmental processes of the universe, and to discover and clarify new physical laws that go beyond the Standard Model of particle physics.

The KEK B Factory accelerator (KEKB), which was the predecessor to SuperKEKB, achieved the best beam collision performance (the highest luminosity) in the world. Following that achievement, KEKB continued to set new luminosity records. By analyzing the large quantities of data generated by the collisions of electron and positron beams at KEKB, the Belle group experimentally verified the Kobayashi-Maskawa theory by observing the first signal of CP asymmetry in B mesons (The Nobel Prize 2008). However, the Kobayashi-Maskawa theory alone cannot completely explain the deficit of anti-matter. Hence, it is necessary to increase the experimental data samples and do further research.

For this purpose the KEKB accelerator group undertook the project of upgrading KEKB to SuperKEKB, for higher luminosity.

The Belle II detector is being assembled by the Belle II collaboration, an international research organization hosted by KEK IPNS (Institute of Particle and Nuclear Studies).

There are over 600 scientists in the collaboration from 98 scientific institutions (23 countries).

A group of physicists and engineers from The Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN) has been a member of the Belle II collaboration since its inception. Current participation is a continuation of that activity. We are engaged in the work of the silicon vertex detector SVD, the development of the infrastructure for data and methodologies for future measurements in the Belle II experiment.

First turns and successful storage of beams in the SuperKEKB electron and positron rings