UPDATE Lead AttenuatorS and LENSES

1. UPDATE Lead AttenuatorS and LENSES Dorothea Pfeiffer GIF++ Project Meeting 26.09.2012

2. Lead attenuators • Asked Calder Industrial Materials Ltd for quote for two of the field uniformity lenses Bart simulated: • Spherical lense: 5456.31 Euros • Double cylindrical lense: 4951.16Euros • Will be mounted onto metal sheet (free issue plate) • Lead type used will be to BS3909/2 4%Sb alloy • Lead time will be 8-10 weeks from time of order and receipt of the free issue plates • Tolerances will be as per drawings, the flatness tolerance on the free issue plate will have an effect so will need to be good • Expensive ! Dorothea Pfeiffer

3. Lead attenuators • Received technical drawings of lead attenuators and movement system from Hans Reithler (RWTH Aachen) THANKS! • Also received CNC programming files • Aachen might be willing to help with the attenuators and mechanical system Dorothea Pfeiffer

4. Field uniformity lense • Attempt to find the ideal shape • For 82Pb and Ekin= 662 keV, linear attenuation coefficient μ =1.17 cm-1 • I = I0·exp(-μ·d) • I(x) = cos(α)2· Imax • Opening angle α: 37° horizontally, 28° vertically => α in upper corners: 43° • Ratio corner/center = cos(43°)2 = 0.53 • d(x) = - ln(cos(α)2)/mu Dorothea Pfeiffer

5. Field uniformity lense • Calculation in MATLAB • Fit function to calculated profile • Good fit with function of type: a1·cos(b1·x) + a2·cos(b2·x) Dorothea Pfeiffer

6. Field uniformity lense • Drawing in AutoCAD • Export as *.stl file • Conversion into Geant4 geometry format GDML with STL2GDML (tesselated volume) • Geant4 simulations very slow due to tesselated volume with 6000 vertices • Not enough statistics yet ! • Use Geant4 polycone approximation instead ? • Simulate in FLUKA with polycone approximation ? Dorothea Pfeiffer

7. Field uniformity lense Dorothea Pfeiffer

8. Field uniformity lense Dorothea Pfeiffer

9. Field uniformity lense Dorothea Pfeiffer

10. Field uniformity lense Dorothea Pfeiffer