Measurements and FLUKA Monte Carlo simulations of steel, aluminium, and copper activation at the CMS experiment at the Large Hadron Collider at CERN

The complex radiation environment at CERN’s Large Hadron Collider significantly impacts the radiation protection studies, necessitating innovative approaches. The computational tools currently employed to evaluate radiological quantities for personnel and equipment safety are under continuous development and require systematic validation. The availability of well-documented beam history, luminosity data and detector geometry facilitates large-scale comparisons between FLUKA Monte Carlo simulations and experimental measurements. In this study, thirty-eight activation samples of three materials were positioned and irradiated in the CMS experimental cavern in various locations, and were subsequently analysed by gamma spectrometry and compared to simulation predictions. The FLUKA Monte Carlo code was used to score fluence spectra, which were then weighted using the activation cross section. The time evolution was applied using the newly developed tool to determine the induced activation. A comparison of the calculated and measured specific activities lies within a factor of two for the majority of radionuclides in copper, aluminium, and stainless steel samples, which can be considered good agreement for such a large and complex setup. ... mehrThe present study has identified discrepancies observed for $^{60}$Co and $^{51}$Cr in steel. This benchmark demonstrates the reliability of the FLUKA Monte Carlo code for activation calculations and provides a reference for the computational method developed and used to establish radiological zoning of materials.