Cherenkov ring fit

Cherenkov ring fit

  • GlueX commissioning data
  • geometrical reconstruction
  • bar #3, central region (phi =~-90)
  • pions with [3.8,4.2] GeV/c momentum
  • without per-pixel corrections
  • without lut corrections

Cherenkov photon in the coordinate system of the detector:

Cherenkov photon in the coordinate system of the charge particle:

Geant4 (bar + optical box ambiguities):

Geant4 with correct path in optical box (only bar ambiguities are left):

Commissioning data (pions only):

Event by event fit (mix of pions and kaons). Green line shows expected Cherenkov angle assuming ideal tracking (center of the ring in (0,0)); red - fitted:

Cherenkov ring fit of the accumulated sample of pions without correction (15 mrad cut around expected value):

Cherenkov ring fit of the accumulated sample of pions after correction (equivalent to correction of the bar rotation):

=> improved SPR

Cherenkov ring fit after event by event correction:

=> further improved SPR