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Update on Simulation Studies of the CEDAR Optics

Update on Simulation Studies of the CEDAR Optics. Helen Heath 9 th December 2009. Reminder (see N.Brook’s talk from August). Use Lau’s CEDAR simulation provide Cerenkov photons to current quartz window -> position(x,y,z) and direction(n x ,n y ,n z ) and wavelength

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Update on Simulation Studies of the CEDAR Optics

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  1. Update on Simulation Studies of the CEDAR Optics Helen Heath 9th December 2009

  2. Reminder (see N.Brook’s talk from August) • Use Lau’s CEDAR simulation • provide Cerenkov photons to current quartz window • -> position(x,y,z) and direction(nx,ny,nz) and wavelength • Optical path simulation • Use ROOT and its geometry manager

  3. Z=996mm Z=646mm

  4. Parabaloidal “cones” 10mm depth 25mm depth

  5. Summary of results in August • 10mm cone • 82-87% photon reach PMT cathode • 68-90% of photons reflected off cone reflect off PMT window • 25mm cone • 87-91% photon reach PMT cathode • 29-67% of photons reflected off cone reflect off PMT window

  6. 6 Cone v Parabaloid Efficiency for photons to reach the PMT cathode v z position

  7. 7 Efficiency for different cone depths Shown for conical collection cones Note: there is little increase in efficiency one the cones are above 15mm in length The parabaloid is similar but the efficiency falls more quickly

  8. 8 Source of Losses • Previous simulations assumed losses at surfaces due to • 5nm roughness for mirror • 10nm roughness for cones • Look at cone roughness

  9. 9 Photon loss v cone depth z=646

  10. 10 Escapees

  11. 11 Photon loss v cone depth z=646

  12. 12 Photon loss v cone depth z=646

  13. 13 Summary of Efficiency Studies • Dominant contributions to the photon loss are • Photons escaping the system for depth<7mm • Reflection from the PMT surface 7mm<depth<~10mm • Beyond 10mm the loss at the cone surface may become the dominant contribution but it increases slowly above ~15mm

  14. 14 Photon distributions at PMT • Nick’s studies observed a double peak in the photon angle at the PMT. • Confirmed to be photons reflected from the cone and those that enter directly (see next slide) • Also noted that the distribution across the PMT face is different for these two cases

  15. 15 10mm cone, photon angle to PMT face. Red photons not reflected from cone, blue photons reflected from cone

  16. 16 25mm cone, photon angle to PMT face. Red photons not reflected from cone, blue photons reflected from cone

  17. 17 25mm cone, photon position at PMT face. Red, photons not reflected from cone, black photons reflected from cone

  18. Efficiencies for photons from Pions 18 • 25000 photons • 25mm cone • Efficiency 0.10% for all z

  19. Future plans • To look at the muon halo • Feed in any mechanical design constraints

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