Speaker
Description
The PICO Collaboration operates bubble chambers to search for WIMP dark matter, leveraging the excellent gamma rejection and long live fractions enabled by operating at a lower degree of superheat than the bubble chambers of the 1960s. Located at the SNOLAB underground laboratory, these detectors use fluorinated target fluids optimized for probing spin-dependent WIMP-proton interactions while operating in an ultra-low-background environment. Previous experiments, PICO-2L and PICO-60, set the world’s strongest constraints on spin-dependent WIMP-proton scattering, and the next-generation detector, PICO-40L, is now fully operational and actively collecting physics data.
This talk will provide an overview of the low-radioactivity techniques and background mitigation strategies employed within the PICO program, including radon assay and mitigation efforts, detector cleanliness protocols, and studies of low acoustic parameter background populations. We will discuss ongoing efforts to characterize detector backgrounds and environmental correlations relevant for long-duration rare-event searches. Looking ahead, PICO-500, a 250-liter chamber currently in development and expected to begin commissioning in 2026, will require further advances in low-background operation and radon control to achieve world-leading sensitivity in the search for dark matter.