1. Update G4builder issues CAMBRIDGE Talk written almost entirely by Stan Bentvelsen with a few updates from Christopher Lester ATLAS G4 Workshop December 2000

2. Client of the AGDD generic model Automatically create Geant4 geometry from AGDD xml files Material definitions also from AGDD xml Generic (i.e. Detector NON-specific) Provide set of tools to examine geometry: Visualization using ‘DAWN’ HBOOK histograms with observables as function of (,) radiation length track length step-counter .... G4builder: Goal Stan Bentvelsen / Christopher Lester

3. No ‘Mother envelope’ volumes are required in AGDD: so an iterative method is implemented to calculate the mother-envelopes effective slow-down of tracking of particles (estimate factor ~6) but still generic! Better use could be made of AGDD features: no use is made of envelopes where users HAVE defined them. no identifier scheme But most of ‘Stack’ is implemented Stacks of boxes & tubes Stacks of stack Stacks of compositions G4builder: Remarks Stan Bentvelsen / Christopher Lester

4. libG4Builder: G4Builder methods are encapsulated in one library. In principle you just link to this. Readout geometries and sensitive detectors must be written by user in standard way. G4Builder joins them to physical geometry! “Tweaking” users wishing to generate a “specialised” geometry (eg non-standard step length in a particular volume) may do so in a standard way Bug fixes: Rotation directions fixed (hopefully!) AGDD-boolean operations are now permitted G4builder: Remarks Stan Bentvelsen / Christopher Lester

5. Two valid AGDD xml files are read-in: Material_AGDD.xml ATLAS_AGDD.xml The complete geometry inside volume ‘ATLAS’ is constructed. May choose to view geometry using ‘DAWN’ program. Use DAWN to format the picture: rotation, zoom, re-coloring, style, postscript output G4builder: Usage Stan Bentvelsen / Christopher Lester

6. Szymon Gadomski fires muons through SCT barrel modules created by the G4Builder. Particle step length in the silicon is varied and results compared to testbeam. G4builder: SCT Modules Stan Bentvelsen / Christopher Lester

7. CHAOS: a 2D grid generator set (,) start, step and stop values ‘spread’ option: randomly generate in bin (,) n tracks set particle ID, energy, vertex. Available as UI commands StepAccumulator Define & register observable in header file Automatic accumulation during each G4Step Separated for ‘detector’ and ‘material’ names Interfaced to Hbook histogram Manager Useful tool to inspect AGDD geometry CHAOS + Accumulator Dell’Acqua Stan Bentvelsen / Christopher Lester

8. Geantinos in SCT • An AGDD geometry file for the SCT barrel exists • equivalent DICE geometry • Scan geantinos in (,) to determine characteristics of the SCT geometry • ‘StepAccumulator’ Stan Bentvelsen / Christopher Lester

9. SCT materials • Scan  (0-90o) at fixed value of  (0) • Accumulate the radiation- and track length • Display for various material • cabling and mounting boards clearly visible Stan Bentvelsen / Christopher Lester

10. Material in SCT • Determine • radiation length • track length • step-counter • Function of  support Copper+alumium Scintillator Stan Bentvelsen / Christopher Lester

11. Find the source code for version v4 (compliant to AGDD v4) /afs/cern.ch/atlas/software/cvs/offline/Simulation/G4Utilities/G4Builder Checkout the software and try: make install make test (should run a little example) G4builder remarks Stan Bentvelsen / Christopher Lester