View larger image |To spot rare collisions with WIMPs, dark matter detectors are placed underground so they are shielded from background particles. Another layer of shielding provides further protection, and cooling minimizes natural vibrations of atoms in the device. If the detecting material is solid, the collision between WIMPs and atomic nuclei can liberate electrons and release sound waves, which can later be analyzed. Credit: Source: D. Bauer/Fermilab