Simulation of radiation environments

Simulating radiation environments is crucial in the design phase of new hadron collider experiments or upgrades, especially when extrapolating to new centre of mass collision energies where previous experience cannot be relied on. The generation of radiation fields in the LHC experiments is dominated by proton–proton collisions, with contributions from beam-gas interactions and other machine losses. It is therefore essential to first reproduce the proton–proton collisions, using Monte Carlo event generators such as PYTHIA8 and DPMJET-III. This part of the simulation chain is discussed in Section 4.1.The particles originating from the proton–proton collisions interact with the detector and machine material, causing electromagnetic and hadronic showers which give rise to the complex radiation fields seen in the LHC experiments. This second part of the simulation is dealt with using advanced Monte Carlo particle transport codes such as FLUKA, MARS, or GEANT4. An overview of these codes is given in Section 4.2.Key radiation quantities of interest are extracted from the simulations, such as 1 MeV neutron equivalent fluence and total ionizing dose, and these are discussed in Section 4.3. It is these quantities that are needed by the detector systems for evaluating radiation damage and predicting sensor and electronic performance over the lifetime of the experiment. In Section 4.4, the simulated predictions of radiation backgrounds for each of the experiments is presented. Finally, in Section 4.5, we offer general conclusions and recommendations for the future.