Cryogenic architecture and heat loads for the High-Luminosity upgrade of the Large Hadron Collider (HL- LHC) at CERN

Abstract The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN is a major upgrade project of the LHC accelerator, which will allow increasing the peak luminosity by at least a factor of five beyond LHC’s design value. This upgrade will include the replacement of the final focusing superconducting magnets and the implementation of superconducting radiofrequency crab cavities in the long straight sections of the interaction points 1 and 5 of LHC. The cryogenic part of this upgrade consists in the design, specification, procurement, installation, commissioning, and handover to operation of two new cryogenic plants and associated cryogenic distribution lines at the machine interaction points for the high luminosity insertions dedicated to CMS and ATLAS detectors. The two new cryogenic plants, with an equivalent capacity of 14 [email protected] K, including 3.25 [email protected] K, were defined based on the heat loads of the new superconducting magnets and radiofrequency crab cavities, of the cold powering systems, and of distribution heat loads. This paper presents the details of the static and dynamic heat loads applied to each cryogenic element added for the HL-LHC, the methodology for addressing the maturity of their design, the defined nominal operating modes and finally the required helium refrigerators cooling capacity for each temperature level, considering the effect of luminosity and beam energy.