• CERN
• nuclear
• nucleare
• radiation protection
• radioprotezione
• safety
• sicurezza

The Target Absorber Secondaries (TAS) are located on both sides of the high luminosity interaction regions of LHC (IR1 ATLAS and IR5 CMS) and have the role of protecting the super conducting quadrupole magnets from the debris originating from the collisions taking place at the interaction point and of preventing the magnets from quenching. As a consequence, the TAS is a highly activated component and all operations in its surroundings have to be planned respecting the legal dose limits and keeping the ALARA principle as main guidelines.
During the 2023 shutdown, known as Long Shutdown 3 (LS3), it is planned to proceed with the upgrade of the hardware that will allow the LHC to operate with a higher luminosity at IR1 and IR5. Among the many modi cations required, the TAS has to be substituted with a new one accommodating a larger beam-pipe aperture.
In this document, the scenarios for removing the existing TAS at CMS will be presented, as well as estimates of the doses that the personnel will be exposed to during the corresponding operations.