CERN 
 
   

Celebrating CERN's discoveries and looking into the future

  [ Home ] [ Programme ] [ Neutral Currents ][ W and Z ] [ Press Release ] [ Photos ] [ Courier story ]
   

For more information:
Contact the
CERN Press Office

 

The UA2 detector


The UA2 central calorimeter measured the energy of individual particles created in proton-antiproton collisions. Accurate calibration allowed the W and Z masses to be measured with a precision of about 1%.

The calorimeter had 24 slices like this one, each weighing 4 tons. The slices were arranged like orange segments around the collision point. Incoming particles produced showers of secondary particles in the layers of heavy material. These showers passed through the layers of plastic scintillator, generating light which was taken by light guides (green) to the data collection electronics. The amount of light was proportional to the energy of the original particle.

The inner 23 cm of lead and plastic sandwiches measured electrons and photons; the outer 80 cm of iron and plastic sandwiches measured strongly interacting hadrons. The detector was calibrated by injecting light through optical fibres or by placing a radioactive source in the tube on the bottom edge.
  [ Home ] [ Programme ] [ Neutral Currents ][ W and Z ] [ Press Release ] [ Photos ] [ Courier story ]

© CERN 2003-09-02 Web Communications -- ETT Division