Ultraheavy Dark Matter Search With Electron Microscopy Of Geological Quartz

Self-interactions within the dark sector could clump dark matter into heavy composite states with low number density, leading to a highly suppressed event rate in existing direct detection experiments. However, the large interaction cross section between such ultraheavy dark matter (UHDM) and standard model matter results in a distinctive and compelling signature; long, straight damage tracks as they pass through and scatter with matter. In this work, we propose using geologically old quartz samples as large-exposure detectors for UHDM. We describe a high-resolution readout method based on electron microscopy, characterize the most favorable geological samples for this approach, and study its reach in a simple model of the dark sector. The advantage of this search strategy is twofold; the age of geological quartz compensates for the low number density of ultraheavy composite dark matter, and the distinct geometry of the damage track serves as a high-fidelity background rejection tool.