Bridging Monte Carlo worlds: a new framework for accelerator simulations applied on shielding and machine protection studies

This thesis delves into the critical study of particle transport in matter, particularly emphasisingits implications for machine protection at CERN's accelerator complex and facilities. To conductstudies of this nature, FLUKA and Geant4 stand out within a small group of general-purpose,multi-particle Monte Carlo codes, validated in energies reaching the multi-TeV. However, theirstructural differences and user interface philosophies present significant challenges in obtainingresults with both codes for the same problems. Overcoming these challenges is crucial, consideringthe inherent limitations of MC codes due to their physical models and reliance on specific databasesfor particle transport calculations.A significant contribution of this work is the development of "Moira", a new software thatintegrates the infrastructure of Geant4 with the capability to process FLUKA inputs. This novelGeant4 application allows for a unique comparison of results between the two codes, enablingsimulations with equivalent characteristics, with the primary distinction being the physical modelsused.Using "Moira", this thesis presents a series of simulations using alternative models to FLUKA's, toanalyse shielding and machine protection studies, focusing mainly in scenarios covering sectionsthat span hundreds of meter in the Large Hadron Collider. Doing these simulations with multiplephysics models permit to obtain a better quantification of the systematic errors, and also contributesignificantly to the development of Monte Carlo codes.