Ancient minerals as paleo-detectors: the search for high-throughput, nanometer-scale microscopy for the frontier of neutrino and dark matter detection

Using ancient minerals as paleo-detectors is a new experimental approach to astrophysical and atmospheric particle detection. At the University of Michigan, we scan natural minerals with a variety of microscopy techniques, like transmission electron and x-ray microscopy, in search of crystal defects from neutrino and dark matter interactions that have been preserved in the crystal lattice for billions of years. These defects, called nuclear recoil damage tracks, can extend up to a millimeter in length, but are only a few nanometers wide. Additionally, our minerals (mostly silicates like quartz [SiO2] and olivine [(Mg, Fe)2 SiO4]) are highly beam-sensitive and have low x-ray contrast, overall making it very difficult to image these small defects with full-field microscopy techniques. We are searching for a microscopy method that balances high volume throughput (10^-3 grams) with nanometer-scale resolution. We present a discussion of this novel method of particle detection as it relates to microscopy constraints and challenges, and elaborate on the exciting future of probing billions of years into Earth’s past to uncover the most intriguing mysteries of our universe.