The Calorimeter

The calorimeter is one of the major components to benefit from detailed simulation. There are three options to determine the detail of this simulation and are flagged by the value of an integer variable ICALOPT in the routine UGEOM (FFREAD card CALOPT).

In the Brahms release 300 and higher significant changes have been introduced for the handling and storage of calorimeter hits. The calorimeter geometry is now the one described in the TESLA TDR. The baseline option is using a very finely segmented SI-W calorimeter as electromagnetic calorimeter, and a scintillator - Iron tile calorimeter as the HCAL. Currently the alternative option of using a very finely segmented hadronic calorimeter with purely digital readout (cell hit or not hit) is not (yet) implemented in Brahms.

The calorimeters are simulated with cells of approximatley $1 \times 1 cm^2$ cells, even in the HCAL. The cells are then recombined into more realistic cells in the reconstruction step. Currently only one version exists, which simulates the analogue HCAL with cell sizes of $5\times5 cm^2$ and larger.

For a detailed description of the calorimeter simulation and reconstruction the reader is referred to [8], which is included in this note as an appendix. Means of accessing the calorimeter information are discussed later in this manual.

At the moment the SI-W and Scintillator-Fe systems are selected by default. The older implementations are still available within Brahms, but are no longer maintained. Details about the older calorimeter simulation are available in older versions of this note. Its use is discouraged, since the system is no longer supported.