Calorimeters

Liquid Argon Calorimeter

The Liquid Argon (LAr) Calorimeter is divided into several components: an electromagnetic sampling calorimeter with 'accordion-shaped' lead electrodes in the barrel and in the endcaps, a hadronic calorimeter using flat copper electrodes in the endcaps, and a forward calorimeter close to the beampipe in the endcap made from copper and tungsten. In addition, presamplers consisting of one layer of LAr in front of the electromagnetic calorimeter help to correct for the energy loss in front of the calorimeter (mainly due to cryostat walls and the barrel solenoid).

Tile Calorimeter

The Tile Calorimeter is a large hadronic sampling calorimeter which makes use of steel as the absorber material and scintillating plates read out by wavelength shifting (WLS) fibres as the active medium. It covers the central range |η| < 1.7. The new feature of its design is the orientation of the scintillating tiles which are placed in planes perpendicular to the colliding beams and are staggered in depth. A good sampling homogeneity is obtained when the calorimeter is placed behind an electromagnetic compartment and a coil equivalent to a total of about two interaction lengths of material. The Tile Calorimeter consists of a cylindrical structure with an inner radius of 2280 mm and an outer radius of 4230 mm. It is subdivided into a 5640 mm long central barrel and two 2910 mm extended barrels. The thickness of the calorimeter in the gap is improved, which has the same segmentation as the rest of the calorimeter. The total number of channels is about 10000.