FIRST RINGS in COMPASS RICH-1
( http://wwwcompass.cern.ch/compass/detector/rich/first_rings/first_rings.html )
ABOUT WHAT IS DISPLAYED
-
only tracking downstream RICH-1 is available:
the trajectory is reconstructed backward
and aftected by multiple scattering (trackers are far)
- the red circles are from track parameters
- for N2 radiator, the refrective index is known
- for the mixture C4F10 and N2,
the refrective index is not known:
C4F10 refractive index is assumed for the red circle
- the yellow histogram is the distribution of
Cherenkov angle values, one per cluster, calculated assuming the
particle trajectory
- from the reconstructed Cherenkov angle,
an indication of C4F10 fraction is obtained: ~50 %
EVENT DISPLAY