1 SLAC simulation workshop, May 2003 Ties Behnke Mokka and LCDG4 Ties Behnke, DESY and SLAC MOKKA: european (france) developed GEANT4 based simulation frame LCDG4: US developed GEANT4 based simulation frame LCDroot: root flavour LCDG4: plain “vanilla” GEANT4 flavour The “holy grail”: Develop a common simulation frame for all LC studies which is shared between different regions. Boundary conditions: conserve (some) level of compatibility with existing frameworks like BRAHMS

1 SLAC simulation workshop, May 2003 Ties Behnke Geometries Defining geometries is one of the most difficult tasks flexible system is needed, to make realisation of different geometries easy System has to support full set of GEANT solids and operations System should allow the definition of sensitive detectors System must allow interface to reconstruction Currently no such system exists! MOKKA approach: database for geometrical constants, drivers to realise the geometries LCDG4 approach: XML description of geometries and sensitive detectors, drivers to realise the detectors in GEANT4 Both systems have their limitations, neither one is really generic but both are being used, and are the best ones on the market at the moment

1 SLAC simulation workshop, May 2003 Ties Behnke Geometry Systems One layer of the VTX detector in XML: The same detector in the MOKKA database:

1 SLAC simulation workshop, May 2003 Ties Behnke Getting geometries into GEANT Data source (xml file, mysql,....) Generic xml interpreter (third party software) Specific GEANT translation routine (“driver”) Mysql parsing software Specific driver routine define hierarchies define relations define sensitive det. Build GEANT geometry model LCDG4 MOKKA

1 SLAC simulation workshop, May 2003 Ties Behnke Comparison XML based scheme Self describing at some level Includes shape information (at some level) Tags sensitive detectors (but needs drivers to translate them into GEANT4) Not easy to switch between different detector / subdetector versions Scaling to complex detectors difficult to see without dedicated software to provide an interface to the user MYSQL based scheme Vaguley self describing Does not include shape information (at the moment) Does not tag sensitive detectors Uses C++ drivers to translate into GEANT4 objects Easy to maintain and switch between different versions of the detector Scaling to complicated detector “easy” Supports every GEANT4 shape

1 SLAC simulation workshop, May 2003 Ties Behnke The MOKKA frame GEANT4 toolkit MOKKA kernel DB XML DRIVER USER Graphics LCIO Reconstruction, Analysis, Event Display, etc

1 SLAC simulation workshop, May 2003 Ties Behnke “Marriage” of both Implement the US XML system as an additional driver in MOKKA: capability to construct the XML based US detectors as MOKKA detectors everything else is common for both: hits, hit formats, etc additional advantage that it allows mixing: extends the capabilities of the XML based system, but retains backwards compatibility sideview of the US SD detector in the MOKKA frame.

1 SLAC simulation workshop, May 2003 Ties Behnke A mixed system: Mix the “TESLA” vertex detector (defined in native mysql) and the SD detector Advantage: Simplicity of xml Complex geometries in mysql

1 SLAC simulation workshop, May 2003 Ties Behnke Hits etal all detectors regardless of the origin share the same hit objects (see Franks talk on LCIO) SD detector with hits in MOKKA simulation

1 SLAC simulation workshop, May 2003 Ties Behnke Histogramming Primarily this is a user responsibility Provide an interface to AIDA to make it easy to book, fill and write histograms. Implementation: use the model of a generalised driver: the user can decide at run time which part he/she wants to use, whether histgramming is part of it Extentable to other parts like event displays, etc etc.

1 SLAC simulation workshop, May 2003 Ties Behnke Whats next with MOKKA/LCDG4 Clean up the interfaces and the code Bring things into the mainstream MOKKA release Implementation of LCIO will be a central point to have people accept one common Kernel Open Questions: Many... geometries: hierarchies links between detectors materials sensitive detectors more generic drivers graphics: quite limited at the moment speed – at the moment MOKKA is significantly slower than BRAHMS for the same events

1 SLAC simulation workshop, May 2003 Ties Behnke LCIO data model Beyond MOKKA Goal: provide a light-weight environment for reconstruction and analysis simple not tightly integrated with any particular package like root, JAS, etc flexible One possibility: “plain C++” frame knows about LCIO and LCIO datamodel talks to reconstruction packages like tracking, energy flow etc provides a simple user interface allows the interaction with more fancy environment like root, JAS etc GEANT4: C++ based Analysis anything Geometry package sim loopana loop LCRECO: C++ based reco loop Digitisation

1 SLAC simulation workshop, May 2003 Ties Behnke Summary and Conclusion I hope we are moving towards a common GEANT4 frame between US and EU MOKKA is a possible candidate for a common platform Major development in the medium term needed for geometry system Next big project is reconstruction frame Will develop a prototype in close collaboration with out US collegues Expect some first results before the end of June this year

1 SLAC simulation workshop, May 2003 Ties Behnke A Higgs event