1. RICH SIMULATION USING GEANT4 S.EASO, RAL. 10-01-2001 OBJECTIVES OF THE SIMULATION. CURRENT STATUS AND PLANS. INTEGRATION WITH LHCb SOFTWARE. SUMMARY.

2. OBJECTIVES OF THE SIMULATION TO SIMULATE THE RICH DATA USING : THE REALISTIC GEOMETRY, THE SOFTWARE FRAMEWORK LHCb PLANS TO USE. WE SHOULD BE ABLE TO USE THIS TO : OPTIMIZE DETECTOR PARAMETERS. DEVELOP A RICH ALIGNMENT PROGRAM. STUDY THE BACKGROUNDS TO THE HPD RESPONSE: EX: CHARGED PARTICLES, BACKGROUND PHOTONS ETC. STUDY THE EFFECT OF MAGNETIC FIELD ON THE HPDS. EVENTUALLY STUDY THE VARIOUS PHYSICS CHANNELS.

3. CURRENT STATUS USED THE GEOMETRY OF RICH1 FROM THE TDR AND LHCb NOTE 2000-077 AS INPUT. CREATED THE NECESSARY MATERIAL DESCRIPTIONS AS INPUT. THESE INCLUDE: C4F10 : REF. INDEX vs WAVELENGTH FROM TESTBEAM STUDIES. MIRROR: REFLECTIVITY vs WAVELENGTH. QUARTZ WINDOW: TRANSMISSION vs WAVELENGTH. ETC. USED A GRAPHICS DRIVER (OPENGL) TO VISUALIZE THE RESULT.

4. RICH1 SIMULATION SENT A 10 GeV ELECTRON FROM THE INTERACTION POINT. FOR THE PRESENT ILLUSTRATION THE FOLLOWING SIMPLIFICATIONS ARE DONE: ALL ELECTROMAGNETIC PROCESSES EXCEPT CHERENKOV RADIATION SWITCHED OFF. THE QUARTZ INPUT WINDOW OF EACH HPD IS SET AS A ‘SENSITIVE DETECTOR’ TO CREATE HITS. THE MIRROR REFLECTIVITY=1.0 FOR ALL WAVELNGTHS. FOR THE QUARTZ WINDOW OF THE RICH VESSEL, THE TRANSMISSION=1.0 FOR ALL WAVELENGTHS.

5. NEXT STEP FOR THE SIMULATION HPD SIMULATION: PHOTOELECTRIC EFFECT TO BE SETUP DIFFERENTLY THAN THE STANDARD GEANT4.. IMPROVE AEROGEL SIMULATION. OPTIMIZE THE SPEED OF SIMULATION: DURING PHOTON GENERATION: REPLACE THE INTEGRATION. INCLUDE THE MAX. QE AND MAX.MIRROR REFLECTIVITY. RICH2 SIMULATION.

6. LHCb SOFTWARE ISSUES TO INTEGRATE WITH GAUDI, SOME OF THE ISSUES: DATABASE: RICH DIMENSIONS FROM ASCII INCLUDE FILE-->XML DB -->GEANT4. LHCb PRODUCTION VS. RICH OPTIMIZATION: RICH SIMULATION USING THE TRACKS FROM GEANT4 PRODUCTION RUN OUTPUT. TO BE DISCUSSED WITH THE LHCb COMPUTING GROUP.

7. SUMMARY GEANT4 SIMULATION OF RICH1 STARTED. THIS IS EXPECTED TO BECOME A USEFUL SOFTWARE TOOL. SUGGESTIONS FOR IMPROVEMENT WELCOME. I PLAN TO BE IN CONTACT WITH THE LHCb COMPUTING GROUP DURING FURTHER DEVELOPMENTS ON THIS.