NaI Detector

The NaI detector is an 88 array of optically isolated NaI(Tl) Polyscin scintillator bars. The dimensions of each bar are 63.563.5406 mm. The array is encased inside an air-tight container. The lateral and rear walls of the container are comprised of 19 mm thick aluminum plates. Covering the front face of the array is a 0.5 mm thick steel sheet, layered with 20 mm of styrofoam and 2 mm of aluminum foil. Light output from the scintillator bars is read with 64 photomultiplier tubes (Philips PM2202) which are coupled to the NaI by 64 pyrex windows with 60 mm Plexiglas light guides. For charged particle identification, a 1 cm thick 54.654.6 plastic veto covers the front face of the array. A diagram of the detector is shown in Fig. 2.5. [1]

  
Figure 2.5: Cross section of the array of 64 NaI(Tl) rectangular crystals.