2) Object oriented design and implementation of an intra-nuclear transport model 20 mn

M.G. Pia (INFN - Sezione di genoiva CERN)

The Hadron Kinetic Model is part of the set of theory driven models for hadronic interactions in the Geant4 Simulation Toolkit.The Hadron Kinetic Model covers the intermediate energy regime of hadronic interactions, O(100 MeV) to O(5 GeV); it can satisfy two use cases for intranuclear transport, both as a hadronic interaction model to be used by the physics processes, and as a back-end to higher energy models. It is capable to handle meson-meson, meson-baryon, baryon-baryon interactions and baryon-antibaryon annihilation, including resonance excitation and deexcitation, as well as pion absorption. A large set of exclusive channels is implemented in the model. Object Oriented technologies play a fundamental role to address the complex physics domain described by this model. The Object Oriented design provides the basis for extensive code reuse by other models, such as cascade models or quantum molecular dynamics models; it also provides the means for easy extension or evolution of the system.

3) Preequilibrium and Equilibrium Decays in Geant4 20 mn

V. Lara (CERN)

For incoming particle energies below O(100 MeV), the precompound reaction mechanism is used to model the high energy continuum region of ejectile spectra and to fill the gap between the arbitrary cutoff of the Intra-Nuclear Cascade models and equilibrium evaporation decays. The behaviour of compound nuclei is then modeled by means of several equilibrium deexcitation models. We present the Object Oriented Design of a semiclassical exciton model for pre-equilibrium decays and the Weisskopf-Ewing evaporation model for equilibrium decays. We present extensions, based on Fermi's break-up model for light nuclei and multifragmentation for very high excitation energies. Fission is treated as a evaporation competitive channel.

4) Comparison of Testbeam Data of the ATLAS HEC 20 mn

D. Salihagic (Max-Plank-Institut fuer Physic, Werner-Heisenberg-Institut)

We present the results of test beam simulations of electrons and muons in GEANT4 for the hadronic end-cap liquid argon calorimeter ( HEC ). Results obtained from GEANT4 simulations varying the range parameters have been compared to GEANT3 simulations and test beam data. For muons the shower profiles have been analysed for different range parameter and for electrons the signal response and the energy resolution have been analysed in dependence of the range parameters

5) Comparison of GEANT4 simulation of CMS ECAL testbeam experiments 20 mn

M. Liedl (CERN)

The electromagnetic calorimeter of the CMS detector at CERN will consist of a barrel and two endcap calorimeters containing a sum of over 80000 lead tungstate crystalls as the active medium. Testbeam experiments with crystalls having the dimension as expected for the final ECAL and beeing arranged in modules and geometric setups similar to their usage in the CMS detector have been carried out at CERN along with GEANT3 simulation. We will present the appropriate GEANT4 simulation and compare it to data and GEANT3 simulation for the following quantities: energy resolution, linearity and position scans.

6) Geant4 for the ATLAS electromagnetic calorimete 20 mn

K. Kordas ?

The ATLAS electromagnetic calorimeter is a sampling calorimeter with its absorber and electrode plates interleaved with liquid Argon (LAr) gaps. These plates have a characteristic accordion shape and 1024 of them are arranged in a cylindrical configuration providing hermetic and uniform $\phi$ coverage of the proton-proton interaction region at the heart of the ATLAS detector. The whole cylinder is actually composed of 16 modules, with the use of 64 accordion plates for each module. The geometry of this calorimeter has been previously described with Geant3, a FORTRAN based simulation package. Recently we have employed Geant4, a package developed by the High Energy Physics community using object oriented programming (C++). Two approaches have been used for the description of this geometry. One describes the full $2 \pi$ volume with the use of trapezoidal, semi-cylindrical and parallelepiped volumes and thus all information for each accordion-shaped volume around the full azimuth is present. The other approach makes use of the Geant4 toolkit to define a new generic Accordion shape in which the relative positions/thicknesses of the LAr, absorber, and readout electrode volumes are all defined. Then, only the $\phi$-position of each accordion volume is defined and thus a smaller number of parameters is used to describe the whole electromagnetic calorimeter. Consequently, this approach is more memory-friendly which is especially useful when constructing large multi-volume detectors. One part of this contribution deals with the extensive comparisons between the two geometry models which are performed in order to prove the validity of the novel approach. The other part deals with the physics validation of the Geant4 product. One of the calorimeter modules has been tested at CERN and its response to muons and electrons is studied. Geant4 is used to describe the complete geometry of the test beam setup (cryostats, etc.), as well as to also simulate the deposited energy in this electromagnetic calorimeter module. Preliminary results on the comparisons between test beam data and the Geant3 and Geant4 simulations of the calorimeter's response to muons and electrons are presented.

7) Comparison of Experimental Electron Signals with GEANT3 and GEANT4 Simulations for the ATLAS Forward Calorimeter Prototype 20 mn

R. Mazini (Université de Montréal)

A pre-production prototype of the ATLAS Forward Calorimeter, a liquid argon sampling calorimeter featuring cylindrical thin-gap electrodes in copper or tungsten absorbers, has been subjected to a testbeam with electrons, pions and muons in 1998. The electron runs have been simulated in great detail in the GEANT3.21 and the GEANT4 frameworks. We present first results on the comparison of signal linearity, energy resolution and lateral shower shapes for electron energies between 20 and 200 GeV.

Tuning of Hadron Calorimeter in GEANT4 using testbeam data.

S. Banerjee ?

Performance of the CMS hadron calorimeter was studied by exposing prototype modules to testbeam. These results will be compared to simulation studies of the hadron calorimeter using GEANT4.