Injection operation into multiple storage rings at KEK electron/positron 7-GeV injector linac (2)

KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded toward the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project of KEKB, in order to increase our understanding of flavour physics. This project requires ten-times smaller emittance and five-times larger beam current in injection beam from the injector. Many hardware components are being tested and installed. Even during the 6-year upgrade, it was requested to inject beams into light source storage rings of PF and PF-AR. Furthermore, the beam demanding approaches from those storage rings are different. SuperKEKB would demand highest performance, and unscheduled interruption may be acceptable if the performance would be improved. However, light sources expect a stable operation without any unscheduled break, mainly because most users run experiments for a short period. In order to deal with the both requirements several measures are taken for operation, construction and maintenance strategy including simultaneous top-up injections in the virtual accelerator concept. (author)