|
|
The OPAL Barrel Lead-Glass Calorimeter |
The barrel lead glass calorimeter, consists of a cylindrical array of 9440 lead glass blocks of 24.6 radiation lengths, located at a radius of 2455 mm, outside the magnet coil, covering the full azimuthal angle and |cos(theta)| < 0.82. The calorimeter is instrumented with magnetic field tolerant phototubes.
The logitudinal axes of the lead glass blocks point towards the interaction regoin to minimize the probability of a particle traversing more than one block. However, the blocks are tilted slightly from a perfectly pointing geometry to prevent neutral particles from escaping through the gaps between the blocks. In the z direction, the calorimeter is segmented into 59 blocks. In the phi direction, the calorimeter is segmented equally into 160 blocks.
Here you can see an image of the lead glass.
OPAL calorimeters
The endcap presampler detectors
The endcap lead-glass calorimeters