1. MDC Simulation Yuan Ye 20060110 BESIII Collaboration Meeting

2.  Simulation based on Geant4  Newest & final design parameters from MDC hardware group are used  Ladder shape, different length for almost all layers, affect construct of stereo layers BESIII MDC

3. Geometry Construct Tube & Endplate  Constructed by G4Tube solid

4. Geometry Construct Layers & Cells  Inner field wire layer always have same wire number & distribution with sensitive wire layer  Divide based on inner field wire layer  Treat cell as equal ideal wedge,

5. Geometry Construct Straight Layers & Cells  Use G4Tube Solid

6. Geometry Construct Stereo Layers & Cells  Complicated part  G4Hype  J4TwistTube  G4TwistTube

7.  Shortcoming: must have same twist angle for inner & outer hyperboloid. Overlap between nearby stereo layers  Adjust radius, add ~0.1-0.2mm gap between layers Geometry Construct Stereo Layers & Cells

8. Tracking & Hits Record  Each step will be recorded as a hit  LayerNo, CellNo, E deposit, T tof (Global time), D drift  LR, ,  entrance =  track -  wire, Position,

9. Tracking & Hits Combine  Combine hits of same cell to one hit  MCTruth data are generated E=  E deposit Do X-T conversion D drift etc. of hit have min( T drift +T tof ) Record primary track hit only Hits from different primary track are separated

10. Hits in MDC Tracking & Hit

11. Digitization  Do digitization based on calibration results from exp. data, now from test beam  Direct read those data from MdcCalibFunSvc of Framework, same with Reconstruction   x ~ f(D drift, LR, ,  entrance, Position, E) X-T ~ f(LR,  entrance )

12. Digitization Smear   x = (f  1 2 +(1-f)  2 2 ) 1/2  Sample between  1  2 use f  Sample use  D digi =D drift + D smear If D digi <0, do again

13. Digitization  X-T conversion D digi T drift  Q-T Correct:  T  T digi = T drift + T tof +  T  A temporary noise model are added Simple model: ~C, ~1/r, ~1/r 2  Digitization can be controlled by user at run time: procedure, smear type, noise level, etc.

14. Some Results  x ~110  m 4MeV@1GeV Spatial Residual More results see Zhang Yao’s & Wang Dayong’s reports

15. Summary  Construct geometry : done  Tracking & Hit : done  Co-work with other subdetectors in Boost : done  Beta version passed test and released in Boss 5.0  Digitization : a workable version  Co-work within framework : done  Have been used for Rec. tuning, stereo layer rotate study, etc.

16. Thanks!