In 1968 some groups from MPS Division, such as the Magnet and Ejections groups, were transferred to the newly created Synchrotron Injector (SI) Division, part of the PS Department.

Its mandate was the design and construction of a Synchrotron Injector ("Booster" or "PSB") to increase the injection energy of the Proton Synchrotron (PS).

In 1972 the four-ring 800 MeV Booster was completed.