Updated implementation of collimator materials in SixTrack and MERLIN codes

The High-Luminosity upgrade of the Large Hadron Collider will push various operational parameters of the machine beyond the design values. The LHC beam collimation system turns out to be one of the bottlenecks for the achievement of the future challenging beam parameters. In particular, various limitations have been identified that call for an improvement of the materials used in various collimator types. An R&D program at CERN explores novel composite materials for collimators with improved mechanical robustness and reduced electromagnetic impedance that can address the main limitations of the present system. A new collimator material implementation introduced in SixTrack and MERLIN, simulation codes for beam collimation at the LHC, allows to simulate advanced collimators based on novel composite materials. An immediate application of this novelty in the two codes is to study the effect of the upgrades collimators on the cleaning performance of the collimation system. After presenting the methods used to model composite materials in each code, we apply it to the case of cleaning simulations with novel collimator materials in the LHC, where the results obtained with SixTrack and MERLIN are compared.