The 15-foot bubble chamber looks especially vintage in the fog. A bubble chamber is a device used for the detection and the study of elementary particles and nuclear reactions. Charged particles from an accelerator are introduced into a super-heated liquid, each forming a trail of bubbles along its path. The trails are photographed, and by studying such pictures scientists can identify the particles and analyze the nuclear events in which they originate. Fermilab’s 15-foot bubble chamber was commissioned in 1973. It is no longer operational.