Effect of High-energy Proton Beam Irradiation on the Behaviour of Graphite Collimator Materials for LHC

The results of experimental investigations of the physical-mechanical property changes of graphite collimator materials for LHC (CERN) irradiated at the cyclotron of RRC-KI by protons with energies up to 30 MeV are presented here. The numerical calculations of radiation damage accumulation in the collimator materials under proton beam irradiation in the energy interval from 20 MeV up to 35 MeV and up to irradiation doses of 1019 proton/cm2 have been made, to derive the irradiation conditions at the RRC KI cyclotron. Comparative investigations of physical-mechanical properties of irradiated and non irradiated graphite collimator materials were performed, including analysis of the degradation of main physical properties of these materials (coefficient of thermal conductivity, changes of electrical resistivity, thermal expansion coefficient, changes of density, changes of mechanical properties of these materials: strength analysis, elastic modulus changes, stress to rupture, yield stress, ultimate tensile stress, deformation to rupture). Irradiation experiments were performed at room temperatures (below 100 degree Centigrade) up to a maximum irradiation dose of 3.1019 proton/cm2. The investigations of the main physical-mechanical properties of irradiated collimator materials have been made. The strongest degradation of the physical-mechanical properties function of irradiation dose has been observed along the graphite wires inside the graphite composite materials.