1. Use new detector description in Reconstruction You Zhengyun School of Physics, PKU 2005.7.13

2. Outline XML-ROOT based detector description in Reco.; How to use it for sub-detector Reco; Test result in MUC; Summery;

3. Comparison of Initialization (MUC) MucGeoGeneral MucGeoGap MucGeoStrip IMucGeomSvc Alignment data (Database, ASCII) :: Gap geom data Strip geom data Gap geom data Strip geom data Old Initialization Read Fill MUC ROOT Volume Ptr Gap ROOT Volume Ptr Strip ROOT Volume Ptr :: Connect XML file (same as simu) New Initialization ROOT Geometry Construct XML-ROOT Converter

4. Comparison of Function Realization Old: Functions wrote by ourselves 1. Coordinate translation : define by ourselves, using CLHEP 2. Boundary judgment: only simple shapes, box, ball… 3. … New: Functions offered by ROOT 1. Coordinate translation: easily realized to any level 2. Boundary judgment: easily realized for all shapes 3. Material of a volume 4. Many other functions offered by ROOT… Because the new detector description is based on ROOT, a complete geometry system, ROOT helps us to realize these functions.

5. How to use it Data: the same xml files as used in simulation Mdc.gdml, Tof.gdml, Emc.gdml, Muc.gdml ROOTGeo: A new package added : DetectorDescription----Identifier | --ROOTGeo ---- SubDetectorROOTGeo.cxx.h | -- MdcROOTGeo.cxx.h | -- T ofROOTGeo.cxx.h | -- EmcROOTGeo.cxx.h | -- MucROOTGeo.cxx.h ***GeomSvc: In requirement add : use ROOTGeo ROOTGeo-* DetectorDescription In source file : void InitFromXML() { m_MucROOTGeo = new MucROOTGeo(); m_MucROOTGeo->InitFromGdml(“Muc.gdml”, “Muc”); }

6. How to realize functions Two choices : 1. Keep old member variables, but fill them from ROOTGeo, No changes to member functions. m_StripDX = m_MucROOTGeo->GetStrip(part, seg, gap, strip)->GetShape()->GetDX(); …… Data from XML, functions still those by ourselves. 2. Delete old member variables, rewrite all functions. Coordinate translation to global : m_MucROOTGeo->GetStrip(part, seg, gap, strip)->GetMatrix(2); // two levels up Boundary judgment : m_MucROOTGeo->GetStrip(part, seg, gap, strip)->GetShape()->Contains( *point ); Get Material of a volume : m_MucROOTGeo->GetStrip(part, seg, gap, strip)->GetVolume()->GetMaterial(); No data in member variables, all functions from ROOTGeo.

7. Test in Muc Two geometry initialization method: Initialize from ASCII data, Initialize from XML; Get completely identical reconstruction output;

8. Summery Same XML files keeps geometry consistency in Simu. and Reco.; Geometry initialized automatically by GdmlToROOT; ROOT based geometry offer many functions; Makes our work easier; A compact geometry class, all from a pointer;

9. Thank you !