The CDF calorimeter upgrade for RunIIb

The physics program at the Fermilab Tevatron Collider will continue to explore the high energy elementary particle physics until the LHC commissioning. The upgrade of the CDF calorimeter opens a new window for improving the jet energy resolution, important in finding various signals such as Higgs by correcting the energy loss in the dead material and adding information in the jet algorithms using charged particles. It plays an important role in soft electron tagging of b-jets and photon identification in SUSY. The upgrade of the CDF calorimeter includes: a) the replacement of slow gas detector on the front face of the Central Calorimeter with Preshower (CPR) based on 2cm thick scintillator tiles segmented in /spl eta/ and /spl Phi/ and read out by WLS fibers running into a groove on the surface of each tiles. The WLS fibers are placed to clear fibers after leaving the tiles; b) the replacement of the Central Crack Chamber (CCR) with 5mm thick scintillator tiles read with the same technique: To finalize the design parameters we have performed several tests on shape of groove, about the performance of WLS used to capture the signal and the clear fibers used to transport the signal to PM to optimize the light yield. The results obtained during the R&D prototyping show the best configuration chosen is obtained with a sigma keyhole groove.