A cyclotron that includes a magnet assembly to produce a magnetic field to direct charged particles along a desired path. The cyclotron also includes a magnet yoke that has a yoke body that surrounds an acceleration chamber. The magnet assembly is located in the yoke body. The yoke body forms a pump acceptance (PA) cavity that is fluidicly coupled to the acceleration chamber. The cyclotron also includes a vacuum pump that is configured to introduce a vacuum into the acceleration chamber. The vacuum pump is positioned in the PA cavity.