Fabrication of the Fermilab Pre-Series Cold Mass for the HL-LHC Accelerator Upgrade Project

Fermilab is fabricating ten full length cold masses for the high-luminosity Large Hadron Collider Accelerator Upgrade Project (HL-LHC AUP). One practice assembly and one pre-series assembly have been completed. This paper summarizes the construction details. Topics include incoming inspection, bus assembly, component machining, shell forming, beam tube insertion, bus expansion loop installation, instrumentation installation, electrical testing, heat exchanger installation and final assembly welding. Inprocess surveys, alignment measurements and testing are presented and explained. Problems encountered during construction and their solutions are discussed.