Engineering an ASME-Compliant Helium-4 Evaporation Refrigerator for the SpinQuest Experiment

This talk presents the engineering design, safety qualification, and commissioning of a helium-4 evaporation refrigerator developed for the SpinQuest (E1039) experiment at Fermilab. As nuclear experiments increase in energy, higher cooling power and radiation hardened control is required to maintain sub 4K temperatures. As the first high-power helium evaporation system implemented in a fixed-target nuclear physics experiment at the laboratory, the refrigerator was designed to meet rigorous safety and performance requirements under the Fermilab ES&H Manual (FESHM). The system architecture was mapped to ASME B31.3 Process Piping and ASME Boiler and Pressure Vessel Code (BPVC) standards to ensure compliance for pressure, vacuum, and overpressure protection. Unique design challenges included operating within a high-radiation target cave, which required remotely located instrumentation, sensor, and control systems. Relief and thermal management systems were engineered to handle transient heat loads associated with both target microwave pumping and the 120 GeV proton beam. I present commissioning results from July 2024, confirming that the refrigerator achieved its thermal performance and safety objectives. The design framework developed here creates a scalable and standards-based approach for future cryogenic instruments in accelerator-based experiments.