Interaction of the CERN Large Hadron Collider (LHC) Beam with Carbon Collimators

The LHC will operate at an energy of 7 TeV with a luminosity of 10³⁴cm^-2s^-1. This requires two beams, each with 2808 bunches. The energy stored in each beam of 362 MJ. In a previous paper the mechanisms causing equipment damage in case of a failure of the machine protection system was discussed, assuming that the entire beam is deflected into a copper target [1, 2]. Another failure scenario is the deflection of beam into carbon material. Carbon collimators and beam absorbers are installed in many locations around the LHC to diffuse or absorb beam losses. Since the collimator jaws are close to the beam, it is very likely that they are hit first when the beam is accidentally deflected. Here we present the results of two-dimensional hydrodynamic simulations of the heating of a solid carbon cylinder irradiated by the LHC beam with nominal parameters, carried out using the BIG-2 computer code [3] while the energy loss of the 7 TeV protons in carbon is calculated using the well known FLUKA code [4]. Our calculations suggest that the LHC beam may penetrate up to about 10 m to 15 m in solid carbon, resulting in a substantial damage of collimators and beam absorbers.