A Scintillator Tile-Fiber Preshower Detector for the CDF Central   Calorimeter
  The front face of the CDF central calorimeter is being equipped with a new Preshower detector, based on scintillator tiles read out by WLS fibers, in order to cope with the luminosity increase provided by the Main Injector during the Tevatron's Run II data taking. A light yield of about 40 pe/MIP at the tile exit was obtained, exceeding the design requirements. 
Stefano Lami (for the CDF Collaboration)