Ring Imaging Cherenkov Counter

Identify reconstructed tracks as one of the particle : electron, muon, pion, kaon or proton.
 
 

Usage in the analysis:

For the  time being, there is more than one method used  for particle identification in the RICH detector.  Therefore  RICH likelihoods are copied to the parallel RTRI table and the entries in the table RTRA are  reset to -1.  Therefore one should  use one of the special functions, which are implemented to copy the corresponding fields in RTRI back to RTRA or to combine them in the unified likelihood. The later method suffers from the unknown efficiency vs. misidentification relation.

The  following function should be used to copy likelihoods calculated wit one method back to the appropriate places.

This function should be called after the reconstruction in the
usevnt.C
 

Recipies:

 

Note that if you omit HITB in the last command, there will be also RICH standalone package RISE running, which is not needed by RITER, but it consumes a lot of CPU-time!!!

Make sure to include appropriate kuip commands for the track reconstruction in your ARTE kumac and that refit is on, e.g:

Particle identification module RITER needs as an input:

 
 

Output:

 

During the reconstruction, the following field in the table of the reconstructed tracks RTRA are filled.

rtra->flr & 0xff	RITER particle identification flag  : If greater than 0, a track   is within geometrical acceptance of the RICH
rtra->lre	likelihood of electron hypothesis
rtra->lrmu	likelihood of muon hypothesis
rtra->lrpi	likelihood of pion hypothesis
rtra->lrk	likelihood of kaon hypothesis
rtra->lrp	likelihood of proton hypothesis
rtra->lrme	likelihood for multi electron hypothesis
background = 1- (lre+lrmu+lrpi+lrk+lrp)	likelihood for hypothesis that the distribution of photons around track is consistent with backrgound

 
 

Method:

The iterative method is based on the assumption that most of the RICH detector hits, which represent a background in the Cherenkova angle histogram, originate from other tracks within the saame event. An iterative procedure is used to clear such histograms.  A weight is assigned  to each Cherenkov photon hit - track pair. After the iterations, the photon hit has the highest weight  for the track, where represents the signal and lowest where it is part of the background.

The weigted photon hits are used for the  calculation of  likelihood functions for different hypotheses.

The method is described in more detail in