Sometimes the unexpected happens. The revival of 5-cell 500 MHz accelerator cavities is a good example:
These 5-cell resonators date back almost half a century ago. They were developed at DESY in Hamburg in the 1970s to accelerate electrons in PETRA, at that time the world’s largest accelerator and used to deliver electron-positron collisions for particle physics experiments.
Later on, this type of cavity became the work horse for various synchrotrons, and ACCEL/RI qualified as a designer and manufacturer after modifying these cavities for DESY and manufacturing a total of 21 in the mid 1990s. We supplied several synchrotron projects all over Europe with these cavities, including auxiliaries such as high-power couplers and tuners.
With the decommissioning of HERA, another large accelerator at DESY, many of these 5- and 7-cell cavities became available and were re-used by labs all over the world. In those days, we at RI were convinced that the market for these cavities would be saturated for decades, especially as more modern, higher-order-mode damped cavities as developed by BESSY (Helmholtz-Zentrum Berlin) entered the market. However, recent years proved us wrong. After the Brazilian synchrotron Sirius, also the new light source HEPS at IHEP in Beijing will operate with 5-cell 500 MHz cavities in its booster ring. Needless to say, it is our great pleasure to deliver these cavities.