Reconstructing a Dilution Refrigerator for Use in Low Energy Nuclear Experiments

The High Intensity Gamma Source Frozen Spin Target, or HIFROST, is a system designed to cool and polarize target material for nuclear experiments. This system will be used in experiments at the Triangle Universities Nuclear Laboratory (TUNL) in Durham, North Carolina. At the center of this system is a dilution refrigerator, a machine that uses a series of pumps and the quantum properties of two stable isotopes of helium to achieve temperatures below 100 mK. Preparations for polarized target experiments were put on hold when an inoperable leak in our dilution refrigerator was discovered in November of 2017.
Since then, we have dedicated our time to designing, fabricating, and assembling a new dilution unit for the refrigerator. This process has been met with unfortunate setbacks in the form of welding mishaps, design errors, and the Covid-19 pandemic. Although these setbacks were frustrating, they were also educational. Using the SolidWorks software to make the design, we were able to fully explore the process of making a dilution refrigerator and gain a wealth of knowledge in translating the ideal image we see from our perspective as physicists, into the real world scenario of engineering and machining.
In addition to the refrigerator, we also worked on systems that were directly and indirectly related, such as installing a new waveguide, configuring a new residual gas analyzer, and setting up our electronics rack. This dissertation will discuss what has been done, how we did it, and what we still need to do.