I study properties of polarized helium-3 at room temperature, 4 K, and below. Here is a link to my dissertation. It has a lot of relevant information if you’re wanting to learn more.

The device shown above was the experimental region that I (mostly) built inside a cryostat at the Triangle Universities Nuclear Laboratory (TUNL) on Duke University campus. The polarized helium-3 was injected into the cubic cell which was covered with a wavelength shifting coating. A nuclear magnetic resonance (NMR) signal was detected using coils inside the gold foil cylinder to the left of the measurement cell.

The purpose of these experiments was to develop an understanding about how helium-3 will behave inside a cell of this type. This information will be useful for planning the Neutron Electric Dipole Moment (nEDM) experiment for the Spallation Neutron Source (SNS) at Oak Ridge National Lab. In that experiment helium-3 will be used as a co-magnetometer, polarization analyzer, and detector for ultra-cold neutrons (UCN).

If an nEDM is observed, this would demonstrate time-reversal violation, which is presently expected to exist due to known CP violation. If found, this would offer some explanation as to how a Big Bang could have occurred, resulting in the universe we observe today. (If you're feeling this paragraph is rather sciency and cryptic, that's because it is! We are investigating the fundamental nature of the universe.)

A significant part of my contributions to our collaboration has been developing the knowledge and skills to include Superconducting QUantum Interference Devices (SQUID) in present and future experiments. They are among the most sensitive magnetic field detectors humans can build. SQUIDs operate by relying on quantum properties of Cooper pairs crossing classically forbidden boundaries inside a superconducting loop.

I have built many Spin Exchange Optical Pumping (SEOP) cells. The challenge in creating the cell is cleaning and coating the interior with Rubidium (Rb) because Rb is extremely reactive to oxygen and water. Once the SEOP cells are created, they are filled with helium-3 and a much smaller fraction of N2. They are then placed in an oven while being exposed to laser light and a magnetic field. When the conditions are just right, this polarizes the helium-3 nuclear spin states.

Presently, I am designing and building a SQUID sensor system with four SQUIDs to detect helium-3 signals in a new experiment. This system is part of the Systematic and Operational Studies (SOS) apparatus which will be installed in the PULSTAR reactor on NC State campus. The SOS uses a dilution refrigerator to reach temperatures as low as 0.4 K. The building and commissioning of the cryostat is taking place at the TUNL facility.

My work includes selecting and testing a high shielding factor cabinet for the room temperature electronics, integration of the SQUID system with the NMR control system, working directly with a SQUID manufacturer to develop a new type of SQUID with an on-chip cryoswitch, designing all components to be placed inside the cryostat, and building this system.

The image above is the SOS cryostat we are building for PULSTAR. The frame is roughly 15 ft tall. The cryostat has a diameter of about 44 inches.