1. Validation of Geant4 (V4.2) for GLAST-LAT -Comparison with Theory, Beam Test Data and EGS4 – S. Ogata, T. Mizuno, H. Mizushima (Hiroshima/SLAC) P. Valtersson, M. Sjogren (Royal Inst. of Tech/SLAC) T. Kamae, H. Tajima (SLAC) (Note) This report covers the work done between Dec. 2000 to Nov. 2001 at SLAC. Note that similar work has been in progress in Italy. Our focus has been in the electromagnetic processes. (Contents) 1.Comparison with Theory 2.Comparison with Results of Beam Test Engineering Model 3.Comparison with EGS4

2. Bethe-Bloch Formula Default Geant4 parameters used in the study (exception: EM shower study)

3. Landau distribution (proton1)

4. Landau Distribution (proton)

5. Landau Distribution (proton3)

6. Landau Distribution (Electron1)

7. Landau Distribution (Electron2)

8. Mean range (Proton1)

9. Mean range (Proton2)

10. Pair Creation (G4 vs. EGS4: Fix needed in G4) No.1

11. Pair Creation (G4 vs. EGS4: Fix needed in G4) No.2

12. Moller Scattering (G4 vs Theory: Fix needed in G4?)

13. Multiple Scattering (G4 vs. BTEM: Proton) No.1

14. Multiple Scattering (G4 vs. BTEM: Proton) No.2

15. Average Cluster Size (G4 vs. BTEM: Proton and Positron)

16. Average Cluster Size (G4 vs. BTEM: Different proton runs)

17. Average No. Hits (G4 vs. BTEM: Proton and Positron)

18. Average No. Hits (G4 vs. BTEM: Positron w/ charge sharing)

19. Average No. Hits (G4 vs. BTEM: Positron w/lower threshold)

20. Total No. Hits (G4 vs. BTEM: Proton/Positron at 0/30 deg)

21. Cluster Size (G4 vs. BTEM: Proton at 0 deg: No.1)

22. Cluster Size (G4 vs. BTEM: Proton at 0 deg: No.2)

23. Cluster Size (G4 vs. BTEM: Proton at 30 deg: No.1)

24. Cluster Size (G4 vs. BTEM: Proton at 30 deg: No.2)

25. Cluster Size (G4 vs. BTEM: Positron at 0 deg)

26. No. Hits (G4 vs. BTEM) Positron at 0 deg)

27. No. Hits (G4 vs. BTEM) Positron at 30 deg)

28. Average No. Hits (G4 vs. BTEM: Positron after a cut)

29. Average No. Hits (G4 vs. BTEM: Positron study)

30. EM Shower (G4 vs EGS4): Cutoff Parameters

31. EM Shower (G4 vs EGS4): Geometry1

32. EM Shower (G4 vs EGS4): Geometry2,3

33. EM Shower (G4 vs EGS4): Energy Leakage after 20RL

34. EM Shower (G4 vs EGS4): Longitudinal Profile No.1

35. EM Shower (G4 vs EGS4): Longitudinal Profile No.2

36. EM Shower (G4 vs EGS4): Lateral Profile No.1

37. EM Shower (G4 vs EGS4): Lateral Profile No.2

38. EM Shower (G4 vs EGS4): Lateral Profile No.3

39. EM Shower (G4 vs EGS4): Lateral Profile No.4

40. EM Shower (G4 vs EGS4): Profile near the Core No.1

41. EM Shower (G4 vs EGS4): Profile near the Core No.2

42. EM Shower (G4 vs EGS4): Parameter Dependence

43. Conclusion Validation of Geant4 (V4.2) for GLAST-LAT -Comparison with Theory, Beam Test Data and EGS4 – (Note) This report covers the work done between Dec. 2000 to Nov. 2001 at SLAC. Note that similar work has been in progress in Italy. Our focus has been in the electromagnetic processes. (Conclusion) 1.Geant4 is as good as any existing EM simulator now 2.Implement in BFEM G4 and study effects of proposed fixes (angular distr.)