Dr. Kara Keeter, physics professor at BHSU, talked about her experiment Dark Side (Depleted Argon Kryogenic Scintillation and Ionization Detector) and its second-generation advancement, MAX (Multi-ton Argon and Xenon detector) during a BHSU luncheon lecture series Thursday. An experiment that uses argon as a noble liquid held at cryogenic temperatures that will scintillate when an atom recoils after colliding with other particles, Dark Side will search for the Weakly Interacting Massive Particles that make up dark matter. This experiment is still in its design stages, possibly for the Sanford Lab. While designing the first experiment, Keeter explained that scientists developed plans for MAX, an expanded version of the Dark Side experiment that will use both argon and xenon noble liquids as twin targets that will increase scientists’ confidence levels after detecting WIMPs. The National Science Foundation has funded the engineering and design of MAX as a DUSEL experiment, Keeter said, and if it is built it will push the limits of sensitivity for WIMP detectors.

While they work on designing MAX, Keeter said scientists at BHSU have to figure out a way to eliminate chemical impurities that can distort the WIMP signal in the detector. In order to do this, BHSU scientists are designing and building a custom laser spectroscopy system that will measure chemical impurities. The system will be used by MAX and Dark Side, she said, but noble liquid experiments around the world, including the Large Underground Xenon experiment that is currently preparing to deploy in the Sanford Lab, are interested in it. Further, Keeter said the system could have commercial appeal.

“I think our experiment is going to make very good use of taxpayer dollars,” she said.

Keeter explained that physicists believe dark matter exists because the movement of galaxies suggests that there is more matter in the universe than what we can see. According to certain laws of physics, the stars on the outer edge of galaxies should rotate slower. However, she said, that is not the case. Therefore, scientists are searching for a way to explain this violation — dark matter that consists of weakly interacting massive particles (WIMPs).

Neutrinos, elusive sub-atomic particles that emanate from the sun, Keeter said, are a form of WIMPs. However, she said neutrinos do not have enough mass to fully explain the gravitational pull of the universe, and therefore the search for more WIMPs continues.