1. SOURCE SHAPE AND COLLIMATOR OF GIF++ IRRADIATOR Dorothea Pfeiffer GIF++ Project Meeting 10.04.2013

2. Algorithm field uniformity lense  Attempt to find the ideal shape using point source  For stainless steel and E kin = 662 keV, linear attenuation coefficient μ = 0.5845 cm -1 I = I 0 ·exp(- μ ·d)  I(x) = cos( α ) 2 · I max  Opening angle α : 37° horizontally, 37° vertically => α in upper corners: 47°  Ratio corner/center = cos(47°) 2 = 0.465  d(x) = - ln(cos( α ) 2 )/mu 2 10.04.2013 Dorothea Pfeiffer

3. Fit 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) 3 Dorothea Pfeiffer 10.04.2013

4. Real scale field uniformity lense  In Geant4 implemented as polycone with 20 sections 4 Dorothea Pfeiffer 10.04.2013

5. 137 Cs Source in RSL6040 capsule 5 Dorothea Pfeiffer 10.04.2013

6. Collimation window and source  Collimation window pyramid shape (converges in center of source in one point)  Collimation window trapezoid shape (schematic drawing, angles should be +/-37 ° horizontally and vertically ) 6 Dorothea Pfeiffer Side view Top view LeadSteel 137 Cs Air Trapezoid shaped Pyramid shaped

7. Pyramid shaped collimator yz 7 Dorothea Pfeiffer Point source Cylindrical source 10.04.2013 Large difference between point and cylindrical source

8. Trapezoid shaped collimator yz 8 Dorothea Pfeiffer Point source Cylindrical source 10.04.2013 No difference between point and cylindrical source

9. Energy distribution point source 9 Dorothea Pfeiffer 600 – 662 keV 300 – 600 keV0 – 300 keV 10.04.2013

10. Reserve slides 10 Dorothea Pfeiffer 10.04.2013

11. Pyramid shaped collimator xz 11 Dorothea Pfeiffer Point source Cylindrical source 10.04.2013

12. Trapezoid shaped collimator xz 12 Dorothea Pfeiffer Point source Cylindrical source 10.04.2013