Single muon highlights the M in CMS
CMS stands for "Compact Muon Solenoid". The solenoid is a powerful magnet system that bends the paths of muons, particles that penetrate from the collision at the center of the detector all the way out. The red track emerging at about 10 o'clock in the large image is a muon candidate. The reddish panes that it intersects are parts of the detector activating as the muon passes through. In the frame on the lower right the same track points upward. Note the curved path, the work of the solenoid magnet. This curvature gives us a very good read on the momentum of the muon. Where do you think all those other tracks (in yellow) come from?