Speaker
Description
The Large Hadron Collider (LHC) at CERN is currently in the early stages of Run 3, i.e. the third operational period of its lifecycle during which the machine will provide particle collisions to the four experiments located along the accelerating ring. Starting from the end of 2025, a three-year Long Shutdown (LS) period, denoted as LS3, will follow. The upgrade work foreseen during this stop represents an essential milestone for the LHC, bringing it to the second phase of its physics programme (High Luminosity LHC, HL-LHC).
To fully exploit the HL-LHC increased delivered luminosity, the LHC experiments have scheduled major upgrades to their detectors. Among the others, this is the case for the Compact Muon Solenoid (CMS), which has planned the installation of new components, as well as the dismantling of some others. This process is organised according to a complex work plan, during which the CMS configuration is sequentially modified over time to make accessible its various parts, including the innermost areas of the detector. In such a complex scenario, the radiological impact of the activated components must be assessed.
This paper focuses on the preparation of a Long Shutdown inside the LHC experiments from an operational radiation protection viewpoint, presenting CMS as a case study. In particular, the computational methodology developed at CERN to assess the residual ambient dose equivalent rates inside the experimental caverns based on the FLUKA Monte Carlo code is discussed.
First, LHC Run 3 operational parameters are addressed, as well as the computational tools required for the analysis. Afterwards, focusing on the CMS case study, the pipeline of configurations foreseen for LS3 is illustrated. Eventually, the most representative results of this assessment are presented and briefly discussed. These will provide the CMS collaboration with useful data to organise LS3 following a dose optimization approach.