English: Cyclotron Dees at the Lawrence Hall of Science.

These electrical elements are contained within a disk-shaped vacuum chamber.

Each D encloses a hollow chamber open along the straight edge. These are connected electrically to opposing phases of a radio frequency source. Electrons are forced to circulate by a perpendicular magnetic field and are accelerated each time that they pass the gaps between the dees.

The serpentine pipes are for the circulation of cooling fluid, required since stray particles will impinge upon and heat the surface of the dees.

Uploaded to the english Wikipedia by the photographer, en:User:Leonard G.