A part of a magnet from the Orsay synchrocyclotron, now used by the proton therapy center (to be replaced in 2008 by newer technologies)

A synchrocyclotron is a cyclotron in which the frequency of the driving RF electric field is varied to compensate for the mass gain of the accelerated particles as their velocity begins to approach the speed of light. This is in contrast to the classical cyclotron, where the frequency was held constant. Image File history File linksMetadata Download high resolution version (1944x2592, 2134 KB) Magnet of the synchrocyclotron at the Orsay proton therapy center Copyright © 2005 David Monniaux File links The following pages link to this file: Synchrocyclotron Metadata This file contains additional information, probably added from the digital camera or scanner... Image File history File linksMetadata Download high resolution version (1944x2592, 2134 KB) Magnet of the synchrocyclotron at the Orsay proton therapy center Copyright © 2005 David Monniaux File links The following pages link to this file: Synchrocyclotron Metadata This file contains additional information, probably added from the digital camera or scanner... Musée dOrsay Exterior view in the afternoon Musée dOrsay Inside the main hall The Musée dOrsay is a museum in Paris, situated on the left bank of the River Seine. ... Proton therapy is a kind of external beam radiotherapy where protons are directed to a tumor site. ... 60-inch cyclotron, circa 1939, showing beam of accelerated ions (perhaps protons or deuterons) escaping the accelerator and ionizing the surrounding air causing a blue glow. ...

(disputed — see talk page) Synchrocyclotrons have not been built since the isochronous cyclotron was developed.

Isochronous cyclotrons maintain a constant RF driving frequency and compensate for the relativistic mass gain of the accelerated particles by increasing the magnetic field with radius. Isochronous cyclotrons are capable of producing much greater beam current than synchrocyclotrons.

See also

• Cyclotron — this contains a mathematics section that assumes constancy of mass, and an extensive see also section.
• Betatron