Caption

UA2 particle detector. Worker assembling the underground area 2 (UA2) particle detector at CERN (the European particle physics laboratory) near Geneva, Switzerland. The detector was placed around the super-proton-synchrotron (SPS) particle accelerator. In 1983 UA2, together with UA1, was used in experiments that discovered the W and Z particles, the mediators of the weak nuclear force. The discovery earned the 1986 Nobel Prize in physics for the UA1 team leader Carlo Rubbia.