When Chris Chiller said, ?The most important thing is that we have achieved separation,? he was referring to the research on which he and wife, Angela, have been working on for the past three years?not their marriage.
For three years the Chillers, both Ph.D. students in physics at the University of South Dakota (USD), have been designing and building ISUP (Isotopic Separation and Ultra-Purification), a new distillation technology that could revolutionize isotopic separation. Dongming Mei, a principal investigator of the LUX experiment and a physics professor at USD, said ?ISUP will transform the way in which ultra-pure isotopes are prepared for use in advanced materials??specifically materials that that are used in the current and proposed underground experiments at Sanford Lab.
Isotopes are atoms that have the same atomic number but different numbers of neutrons. For example, carbon-12, the most common form of carbon dioxide (CO2), has six protons and six neutrons. Carbon-13, the gas being used in ISUP, contains an extra neutron.
The Chillers? experiment consists of a ?column? into which carbon dioxide is injected. Gravity and temperature pull the CO2 in various ways. ?It?s our job to influence those forces such that we get the isotopes to go in different directions and get them where we want them to go inside the column,? Chris said. ?Then we syphon off the isotopes (using a cryogenic thermosyphon) and put them into sample bottles.?
Angela said the design of ISUP?s thermosyphon system is a direct result of the couple?s work on the LUX (Large Underground Xenon) experiment, which was in the Surface Lab three years ago. ?We were tasked with developing a system for isotope separation. We saw the thermosyphon system LUX was using and said, ?whoa, this could work for us,?? she said.
?Coming here saved us three or four iterations of this piece of equipment,? Chris said referring to the column. ?We were surrounded by people who knew what worked and they passed that knowledge on to us. If we hadn?t come to Sanford Lab, we wouldn?t have been successful.?
While the focus of ISUP is on separating enriched isotopes needed for large-scale underground research, Mei said isotope separation plays a critical role in technology and scientific research into chemistry, environmental and material sciences, and medicine. Separation technologies exist, but they are energy intensive and carry a high production cost.
?We?ve found a way to separate carbon-13 isotopes, which are used in Magnetic Resonance Imaging (MRI), then concentrate them very inexpensively and very quickly,? Chris said.
?Like all of the experiments at Sanford Lab, our process is unique?the only one like it in the world,? Chris added. ?And it?s funded entirely by the state of South Dakota.?
?We?re very proud of that,? Angela said.