# If you could look at the LHC beam, what would you see?

Does the LHC beam generate any photons within the visible light spectrum? Assuming the beam was traveling through air instead of a vacuum, would it interact with the nitrogen or oxygen to generate visible light?

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Does the LHC beam generate any photons within the visible light spectrum?

The LHC circulates in vacuum, with very few interactions with the rare left over atoms and molecules. It produces electromagnetic radiation, synchrotron radiation at the circular parts of the trajectory, as it bends. At 5.5 eV it is in the x-ray part of the spectrum, not the visible.

Assuming the beam was traveling through air instead of a vacuum, would it interact with the nitrogen or oxygen to generate visible light?

Yes, in a transparent medium there would be Cerenkov radiation, part of which is in the visible light. This is used for particle detection.

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As for the physics of what Burgorski saw, I guess it was synchrotron radiation from the accelerating protons. The U-70 operated at energies of $70$ GeV; the LHC in its first phase operated at $7$ TeV $= 100 \times 70$ GeV. Maybe you can do the synchrotron radiation calculation of LHC versus U-70 to see how much brighter the flash would be at the LHC.