SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
False-colour cloud chamber photograph showing a cosmic ray muon (green) knocking out an atomic electron (red). The high-energy muon enters from above & hits the electron out of its orbit in an atom of the mixed oxygen & carbon gas filling the cloud chamber. The relatively low-energy electron curves tightly in the chamber's magnetic field. Muons belong to the family of elementary particles called leptons; they are heavy, penetrating versions of the electron which are formed in abundance when primary cosmic rays from outer space collide with particles in the upper atmosphere.
Model release not required. Property release not required.