ULTRAMAN: A Proposed ultrasound detector for macroscopic dark matter

Abstract

We propose ULTRAMAN (ULTRAsound Macro ANalyzer), a passive ultrasound array experiment designed to search for macroscopic dark matter (macros) through coherent acoustic disturbances generated as compact objects traverse a controlled target medium. Unlike existing dark matter detectors that primarily rely on scintillation, ionization, or other signatures of energy deposition, ULTRAMAN exploits the acoustic response of matter to reconstruct individual highly supersonic trajectories using synchronized multielement ultrasound arrays. The framework connects macro stopping power and interaction cross section to the resulting acoustic pressure, while the expected event rate probes the macro mass and abundance. A genuine candidate would appear not as an isolated radio frequency spike, but as a correlated multichannel track consistent with a single highly supersonic passage through the target. Representative macro, nuclearite, axion quark nugget, and primordial black hole benchmarks are shown to occupy distinct regions of the resulting acoustic observable space. Existing ultrasound technology offers a realistic route to an event-level terrestrial search for macroscopic dark matter, with null observations translating into complementary constraints on its parameter space.