An ASME-Compliant Helium-4 Evaporation Refrigerator for the SpinQuest Experiment

TL;DR

This paper details the design, safety compliance, and commissioning of a high-power helium-4 evaporation refrigerator for Fermilab's SpinQuest experiment, emphasizing ASME standards and remote instrumentation considerations.

Contribution

It introduces the first high-power helium evaporation refrigerator at Fermilab designed with comprehensive ASME compliance for a fixed target scattering experiment.

Findings

System meets all thermal performance objectives.

Successfully achieved safety and pressure vessel compliance.

Operational commissioning confirmed system functionality.

Abstract

This paper presents the design, safety basis, and commissioning results of a 1 K liquid helium-4 (4He) evaporation refrigerator developed for the Fermilab SpinQuest Experiment (E1039). The system represents the first high power helium evaporation refrigerator operated in a fixed target scattering experiment at Fermilab and was engineered to comply with the Fermilab ES\&H Manual (FESHM) requirements governing pressure vessels, piping, cryogenic systems, and vacuum vessels. The design is mapped to ASME B31.3 (Process Piping) and the ASME Boiler and Pressure Vessel Code (BPVC) for pressure boundary integrity and overpressure protection, with documented compliance to FESHM Chapters 5031 (Pressure Vessels), 5031.1 (Piping Systems), and 5033 (Vacuum Vessels). This work documents the methodology used to reach compliance and approval for the 4He evaporation refrigerator at Fermilab which the field lacks. Design considerations specific to the high radiation target-cave environment including remotely located instrumentation approximately 20 m from the cryostat are summarized, together with the relief-system sizing methodology used to accommodate transient heat loads from dynamic nuclear polarization microwaves and the high-intensity proton beam. Commissioning data from July 2024 confirms that the system satisfies all thermal performance and safety objectives.