Directly Detecting Dark Matter with Argon, Xenon, and Xenon-with-a-Twist
The fact that 85% of the gravitating mass in the universe is invisible is one of the biggest unsolved mysteries in fundamental physics today. If this dark matter was not present, galaxies would fly apart and the universe would not develop the right amount of structure at the right time for you to exist and attend this colloquium. Despite its abundance, dark matter has yet to be directly detected in experiments on Earth. Why? The possible mass range for a dark matter particle extends from a fraction of the proton mass to the mass of a typical protein, and these particles are thought to interact very weakly with normal matter. In fact, the radioactivity of a banana is ten billion times higher than the expected number of dark matter interactions over the lifetime of a direct detection experiment. I will talk about how noble liquid experiments like DarkSide (argon) and LUX-ZEPLIN (xenon) attempt to "see" dark matter interactions, and how we deal with the challenge of ambient radioactivity. Lastly, I'll talk about an exciting new idea to increase the sensitivity of a detector like LUX-ZEPLIN by doping its xenon with a light element like hydrogen.