Calorimeter Geometry for TESLA Detector in BRAHMS

Figure 1: 3-D view of calorimeter for TESLA detector. ECAL is shown in yellow, HCAL - in green

Calorimeter for TESLA detector simulation in BRAHMS is very close to the engineering drawings of TESLA-TDR [#!tdr!#]. The BRAHMS geometry of whole calorimeter is shown at the Figures 1,2,3.

TESLA calorimeter consists of two main parts:
ECAL - electromagnetic Si-Tungsten fine granulated calorimeter (shown in yellow) and
HCAL - hadron Tile-Scintillator-Stainless-Steel calorimeter (shown in green).

ECAL barrel consists of 5 octagonal rings (40 modules), see Figure 5.

Sampling structure of ECAL consists of leading part; that is 30 layers of Tungsten (1.4 mm thickness and approximately of 1 x 1 meter in area, differ in depth), and 2.4 mm gap are filled with Si-detector (0.5 mm thickness) and two alveolus surrounded it. And a tail that is 10 layers of Tungsten (4.2 thickness) with the same structure of sensitive gap, see Figure 4.

BRAHMS geometry for barrel part of ECAL was translated from MOKKA geometry (main volume D000). In this geometry every piece of calorimeter is the separated volume.

Two ECAL end-caps (see Figure 5) have exactly the same longitudinal sampling structure as barrel, they are programmed as two octagonal cylinders (volumes ECA1 and ECA2 in accordance with two sampling structures).

HCAL barrel consists of 2 rings (16 modules each), the shape can be seen at Figures 1. Volumes HBA1 and HBA2 are joined into the nontrivial shape - inner octagonal, outer hexagonal cylinders.

HCAL End-Caps consist of 5 octagonal cylinders each (volumes HCA0 - HCA4).

All these volumes are filled with Stainless-Steel and divided into 38 or 53 (for end-cap) sampling structures that consists of 20 mm Stainless-Steel pales and 6.5 mm gap filled with 5 mm thickness scintillator plate (volumes SC-i, area is approximately 1 x 3 meters) and 1.5 mm gap with output fibers (volumes FB-i), see Figure 4.

The whole calorimeter consists of tree different sampling structures, two of ECAL and one of HCAL. That is used at the simulation step - to separate hit storage for the different sampling structures and at the reconstruction step - to get the energy conversion coefficients different for different sampling structures.

BRAHMS subroutines for calorimeter geometry are collected in calobld_109.car.