A preshower detector for the CDF Plug Upgrade: test beam results

A preshower detector consisting of plastic scintillating plates with optica l-fiber readout was tested at the Fermilab meson beamline. The detector was placed at a depth of about 1.5X(0), followed by an electromagnetic and had ronic calorimeter, and exposed to positron, positively charged pion and pos itive muon beams with energies in the range of 5-227 GeV. Multianode photot ubes, HAMAMATSU R5900-M16, were used for the photon readout. The efficiency for detecting two minimum ionizing particles with noise occupancy of < 1% was 90-100% for gains of (1-4)x 10(5). It was also found that by requiring an appropriately large signal in the preshower detector, the rate of charge d pions depositing a large fraction of energy in the electromagnetic calori meter could be reduced by a factor of 1.4-2.0 (1.4-2.8) while keeping 95% ( 90%) efficiency for positrons. (C) 1999 Elsevier Science B.V. All rights re served.