From SICB to Gaudi

1
From SICB to Gaudi

• Why?
• How?
• Define a boarding line
• Create 2 programs
• Event generation
• Event reconstruction
• Status
• SICBMC
• SICBDST

2
Why ?

• Event generation is using Pythia, QQ, Geant3
• digitization is written in Fortran
• simulation of photodetector response is written
  in Fortran
• Event reconstruction is being written in C in
  the Gaudi framework
• tracking is written in C
• it needs digitizings written in Fortran
• A full RICH pattern recognition is written in
  Fortran
• could use a better tracking written in C
• A first version of the RICH pattern recognition
  is written in C
• it needs reconstruction of photon tracks and
  digitizings written in Fortran.

3
How ?

• Define a boarding line between simulation and
  reconstruction.
• Event generation requires Pythia, QQ, Geant3
• it creates Geant3 hits
• it is very CPU time consuming
• Digitization needs Geant3 to decode Geant3 hits
• digitization algorithms are not yet frozen.
• Event reconstruction uses digitizing banks.
• Create 2 programs
• SICBMC
• generates the RawHit banks RawHits do not need
  Geant3 to be understood.
• SICBDST
• digitization, apply trigger, reconstruction.

4
One drawback

• Pileup events
• events are merged at the level of Geant3 hits.
• SICB knows how to read several input Geant3
  files.
• It does not know how to read several input SICB
  bank files.
• SICBDST will not be capable to handle pileup
  events,
• Gaudi will be capable to do it when digitization
  will be written in C.
• A possible solution?
• Keep Geant hit banks and raw hit bank
• In case of required pileup
• run digitization step from the Geant hits to
  digitizings
• store digitizings
• read digitizing file into SICBDST skipping the
  digitization step.

5
SICBMC

• SICBMC is the event generation (simulation)
  program
• it is linked with event generator (Pythia, QQ, )
  and Geant3
• it produces Geant3 hit banks
• Create a RawHit step
• each detector must create rawhit banks from
  Geant3 Hit banks
• it already exists for VELO, MUON, RICH, trackers
• move the code from reconstruction to simulation
• it is being done for ECAL and HCAL
• Remove steps
• digitization, trigger, reconstruction, analysis

6
SICBDST

• SICBDST is the part independent from Geant3 which
  could be moved to Gaudi
• digitization
• create digitizing banks from rawhit banks
• apply trigger
• create trigger banks from digitizing banks
• reconstruction
• create DST banks from digitizing banks
• analysis
• Each module should have its own initialization
  routine, and not make any reference to Geant3
  (common block or routine)

7
Status

• SICBMC
• RawHit step is created
• move VELO, MUON, RICH, tracker code from
  digitization step to rawhit step is done
• create ECAL and HCAL rawhits is on the way.
• Output files can be read in by Gaudi linked
  without Geant3.
• Gaudi linked without Geant3 can read SICBMC
  output file.

8
SICBDST

• SICBDST
• create recevt package to handle the event loop
• digitization with its own initialization
• MUON, trackers - done
• RICH - nearly ready
• ECAL, HCAL - being done
• apply trigger with its own initialization
• everything exist, check the initialization
• reconstruction
• make sure that initialization is done properly
• analysis
• nothing special