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: 4951.16 Euros  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 ! 2 26.09.2012 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 3 26.09.2012 Dorothea Pfeiffer

4. Field uniformity lense  Attempt to find the ideal shape  For 82Pb and E kin = 662 keV, linear attenuation coefficient μ =1.17 cm -1 I = I 0 ·exp(- μ ·d)  I(x) = cos( α ) 2 · I max  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 4 26.09.2012 Dorothea Pfeiffer

5. Field uniformity lense  Calculation in MATLAB  Fit function to calculated profile  Good fit with function of type: a 1 ·cos(b 1 ·x) + a 2 ·cos(b 2 ·x) 5 26.09.2012 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 ? 6 26.09.2012 Dorothea Pfeiffer

7. Field uniformity lense 7 26.09.2012 Dorothea Pfeiffer

8. Field uniformity lense 8 26.09.2012 Dorothea Pfeiffer

9. Field uniformity lense 9 26.09.2012 Dorothea Pfeiffer

10. Field uniformity lense 10 26.09.2012 Dorothea Pfeiffer