Synchrotron light source
Electrons are accelerated to high speeds in several stages to achieve a final energy that can be in the GeV range.  In the Large Hadron Collider (LHC), proton bunches also produce the radiation at increasing amplitude and frequency as they accelerate in the vacuum field, making photoelectrons. The photoelectrons then make secondary electrons from the pipe walls with increasing frequency and density up to 7x1010.  Each proton may lose 6.7keV per turn due to this phenomenon. So, both electron synchrotrons and proton synchrotrons can be a light source.