Do protons in the beam on LHC interact with photons? I wonder how a beam would look from outside. Is there a photo of a proton beam?
Protons carry charge, so of course they interact with the EM field; while synchrotron radiation isn't as big a problem as with electron/positron colliders (which is why there are plans for next-generation linear accelerators, eg ILC and CLIC), the proton beam does radiate.
Afaik the radiation is detected and used to keep track of the beam, but it's been some time since I talked to someone in the know; I also do not know how images like this are generated, but hopefully someone else here does...