Determining properties of the radiator (reflection coefficient, roughness) based on z-scan data.
- CERN 18
- S420, bar with 3-layer spherical lens
- pions and protons @ 7 GeV/c
- geometrical reconstruction
- delta t selection with s = 0.5 ns
- calibration and per z-position plots
Bounces (vertical + horizontal) for unique channel and path id. Accumulated for all (6) z-positions:
Example of ch 487 and path id 10003. For 6 z-positions. Errors represent statistical uncertainty. Fitted with first order polynomial:
Reflection coefficient calculation:
All 6 z-combinations:
Excluded combinations with path id 3 (reflection from the top of the prism):
Resulting reflection coefficient for beam data:
Wavelength distribution of detected Cherenkov photons (@ 30 deg polar angle of charge particle):
Reflection coefficient vs roughness. BaBar data and sims are at Brewster angle. CERN18 data for all angles.
Angle to the normal of the surface for all unique channel-paths combinations:
Geant4 data. Example for 0.5 roughness:
Simulated vs reconstructed. Roughness calculated from reflection coefficient using scalar theory.
