Online resources on radioactivity and gamma radiation at the LHC are primarily concerned with leaking protons, ones that escape the beam and hit various parts of the accelerator complex. Those protons activate the nuclei they hit, making them radioactive. See, e.g., "Taking a closer look at LHC - Ionizing radiation".
A different radiation safety issue at the LHC, or any modern particle accelerator, is the gamma radiation produced intentionally as part of the normal physics operation of the accelerator, that is, the gamma photons produced from the annihilation of the colliding particles.
If the two colliding protons at the LHC turned into two photons, each would have a photon energy of 6.5 TeV and a frequency of 1.57 × 1027 Hz. The two initial protons rarely annihilate into two photons; yet, even an annihilation product, for example the Higgs boson, can decay into two gamma photons, each with an energy of 63 GeV and 1.52 × 1025 Hz frequency. Such gamma rays are produced millions of times per second during normal LHC operation. These exceptionally hard gamma rays are five orders of magnitude more energetic than the highest-energy nuclear decay gamma radiation, which itself is highly dangerous to biological systems.
Under these circumstances, what safety measures can be enacted? What is a good summary of the protection against this type of radiation?