Dark matter makes up 85% of the matter in our Universe, but we have yet to learn its identity. A broad array of search strategies are needed to probe for non-gravitational interactions between dark matter and ordinary matter. While most searches focus on Weakly Interacting Massive Particles (WIMPs) with masses above 1 GeV/c², it is imperative to also consider other motivated dark matter candidates. In this talk, I will discuss dark matter with masses between 1 MeV/c² and 1 GeV/c², which is a theoretically and phenomenologically appealing possibility and presents a new frontier in the search for dark matter. I will highlight novel dark matter direct-detection strategies that can probe this under-explored mass range. I will describe how XENON10 data taken more than 10 years ago currently sets the best constraint on dark matter with masses as low as a few MeV/c². I will then discuss several planned experimental efforts, using xenon, scintillating, and semiconductor targets, that can greatly improve on this constraint. In particular, I will highlight SENSEI, a recently funded experiment that will use new ultra-low-threshold silicon CCD detectors (“Skipper CCDs”), allowing it to probe vast new regions of unexplored dark-matter parameter space in the next few years.

Argonne Physics Division Colloquium Schedule