1. European Organization for Nuclear Research
GDML “Geometry Description for GEANT4 and ROOT” by Daniele Francesco Kruse University of Rome “Tor Vergata”

2. Why GDML? A short answer and a summary of the following presentation
Because we need a standard detector geometry description
language
...a short answer
Summary of the presentation
Who uses GDML?
How does it work?
What is my job here at CERN?
What have I done???

3. Geant4 REAL EVENT SIMULATION
A toolkit to simulate the interactions of particles with matter
REAL EVENT
Particle collision inside
the ATLAS detector
SIMULATION
Computer simulated collision using detector geometry and beam description in Geant4
Geant4
Why ?
1) Correctness of Design
know if the detector design is good for what you want to discover
2) Correctness of Theory and Model
compare your model with what you have in reality (correct theory?)

4. An Object-Oriented Data Analysis Framework
ROOT
An Object-Oriented Data Analysis Framework
Analyse the enormous amount of data generated by LHC
experiments
- The Challenge
- Simulation and Real Events
Analyse data both during simulation and real experiments
- The Geometry Package
ROOT can also be used for simulation purposes if combined with
other simulation software
- Visualization Tools

5. GDML Geant4 ROOT GDML LHC Computing Grid (LCG) Applications
Geometry Description Markup Language
LHC Computing Grid (LCG) Applications
Geant4
ROOT
... to provide a common
geometry data exchange format
GDML

6. Geometry Description Markup Language
GDML
Geometry Description Markup Language
Define
Materials
<material name=“Oxygen” Z=“8”>
<D value=“ ”>
<atom value=“16.0”>
</material>
Define
Solids
<box name=“MyBox” x=“5” y=“10” z=“10”/>
<tube name=“TheTube” rmin=“8” rmax=“9” z=“3”/>
<sphere name=“Ball” rmin=“8” rmax=“9”/>
Define
Structure
<volume name=“Detector”>
<materialref=“Oxygen”>
<solidref=“Ball”>
</volume>
(you can then put this volume in a mother volume)

7. The Binding with ROOT and Geant4
The Interface
The Binding with ROOT and Geant4
Input
GDML file R O T G D M L R O T G e a n t 4 C P G D M L
Output
GDML File

8. My job@CERN The Binding with ROOT and Geant4 The Geant4 – GDML Binding
C++ (good performance)
Support for the exportation of new solids
Multiple GDML files support (input & output)
Output formatting (element names)
The ROOT – GDML Binding
Python (flexible and easy to upgrade)
Support for new complex solids (Xtru, Arb8, etc...)
I/O System refinement

9. Work in progress...
Things that are still on my agenda and will be ready soon...
CPPGDML Core Extensions
Add support for the <matrix> tag
Add support for flow-control tags such as <loop>
ROOT GDML Import Tuning
Enhance performance
GDML Schema Upgrade
Refine solids’ definitions
Add support for the <matrix> and <loop> tags

10. what was this all about? what have I done for CERN?
Conclusions
what was this all about? what have I done for CERN?
1) GDML is more flexible now because you can:
- use many new kinds of solids in your
geometry description
- split huge geometry info into smaller
GDML modular files
2) ROOT is now able to correctly and efficiently
read/write GDML files
3) Geant4 and ROOT have now got a means to share
their geometry information

11. That’s All Folks! Many Thanks to: Witold Pokorski (my supervisor)
for his help and understanding during these 2 months
My good Friends at CERN
for the great times we had together
and to All of You
for your kind Attention...