Daniel Baxter (Northwestern University) Probing the Dark Sector: The Quest for a Background-Free Detector

Abstract:
Dark matter represents one of the most sought after discoveries in physics. Leading theories predict that extremely sensitive detectors could probe nuclear recoils from dark matter interactions. The PICO collaboration uses bubble chambers to look for the energy deposition from such an interaction. The biggest challenge in searching for dark matter is the mitigation and understanding of the numerous other sources of events that could look like dark matter, namely radioactive backgrounds. I will discuss how a long effort to understand backgrounds in the PICO bubble chambers led to the recent background-free result of PICO-60 and how discoveries made along the way might affect other rare event searches.
Bio:
Daniel Baxter is a graduating 5th year PhD student at Northwestern University and active member of the international PICO collaboration searching for dark matter using bubble chamber detectors. His research has largely focused on dark matter detector calibration, specifically understanding differences in detector response between nuclear and electron recoils. He has applied this expertise to the PICO-60 detector as run coordinator of its first physics run, which became the first background-free run of a bubble chamber at the 40L scale.