1. K. LaihemPrinceton meeting Princeton meeting 22-05-2006 Status Report Simulation studies E166 experiment Karim Laihem

2. K. LaihemPrinceton meeting What we have achieved in E166 ? (e+ and photon asymmetry) Convert the X axis from current to MeV Convert the asymmetry to polarization

3. K. LaihemPrinceton meeting Updated geometry E166_Geant4_Simulation

4. K. LaihemPrinceton meeting 18” Entrance region Exit region

5. K. LaihemPrinceton meeting Spectrometer Conversion target Reconversion target 3.6” 7.78” 7.9” 9.4” solenoid Entrance region Exit region

6. K. LaihemPrinceton meeting Solenoid Axial field. The fit function is a Gaussian profile Where the coordinate z is given in centimeter. Solenoid magnetic field. (SLAC’s measurements) (1) (2) (3)

7. K. LaihemPrinceton meeting MERMAID field map implementation into E166_G4_SIM X Y Z (i,j,k) (i+1,j,k) (i,j+1,k) (i+1,j+1,k) (i,j,k+1)(i,j+1,k+1) (i+1,j,k+1) (i+1,j+1,k+1) Z X Y e+/e- Track Figure 19. Scheme of one unitary segment for the 3D interpolation. Figure 20. Scheme of the 3D segmentation using the unitary cube method for the field map implementation

8. K. LaihemPrinceton meeting I L = 0 A I L = 150 A I L = 350 A Solenoid focusing effect. e+ 2D Spatial distribution at the Entrance of the spectrometer. For different IL value (IL = 0, 150, 350 A) (Spectrometer OFF). Focusing effect of the lens is shown

9. K. LaihemPrinceton meeting I S = 120 I L = 200 I S = 160 I L = 250 e+ spatial distribution showing the density (A), at the entrance of spectrometer (B) at the exit of spectrometer (C) and at the reconversion target for different setting points IS and IL. I S = 160 I L = 250

10. K. LaihemPrinceton meeting E166_G4_SIM Figure 33. Positron energy versus spectrometer current. E e+ (180)=7.4 MeV This point can not be seen by the simulation If we use the First harmonic (E cutoff = 8.3 MeV) ? To be clarified

11. K. LaihemPrinceton meeting (E166 Zeuthen group)

12. K. LaihemPrinceton meeting E166_G4_SIM 9 Xtals

13. K. LaihemPrinceton meeting 7% -7% N = 10 4 E e+ = 3.7 MeV P e+ = 70% N = 10 4 E e+ = 3.7 MeV P e+ = 70% 300 bunches CPU time ~24h Asymmetry % = 0.43 ± 1.3 Preliminary

14. K. LaihemPrinceton meeting 100% -100% N = 10 4 E e+ = 7 MeV P e+ = 100% N = 10 4 E e+ = 7 MeV P e+ = 100% 150 bunches CPU time ~17h Asymmetry % = 13 ± 1.4 Preliminary

15. K. LaihemPrinceton meeting Positron Energy [MeV] Positron Polarization [%] Iron Polarization [%] Asymmetry [%] Analyzing power [%] 3.77070.43 ± 1.38.77 799 13 ± 1.4 13 Electron Energy [MeV] Polarization [%] Iron Polarization [%] Asymmetry [%] Analyzing power [%] 799 15 ± 1.0 15 Preliminary Preliminary Test Without Annihilation (polarization=0)

16. K. LaihemPrinceton meeting Summary Code optimization Computer power to see these small asymmetries with reasonable errors. -……… -………….. -………………. -……………………