RICH as a particle identification device - it does clear your signals!

An example: phi->KK, no PID cut (a), hard RICH likelihood cut on both kaons (b).

RICH as a particle identification device - how to do it

A three level identification tool comes from Marko Staric. It allows you to choose the identification level (three levels, soft, medium and hard cut on the likelihoods as given by the RITER algorithm) according to your needs. The routines are available in the arte library.

Alternatively, the likelihoods calculated with the ring search package RISE can be used to make PID selections for the reprocessing 2 data. In the reprocessing 3, a new algorithm replaced RISE.

RICH as a particle identification device - how well does it work

Efficiencies and fake probabilities for various selection criteria were determined by using Ks -> pi+ pi-, phi-> K+ K-, Lambda-> p pi- decays. A complete set of plots can be found here. Plots on the diagonal show the efficiency (e.g. p->p), plots left or right to the diagonal show the mis-identification probability (e.g. p->K).

Individual efficieny/fake probability plot matrices:

  • Reprocessing 2, RITER, soft.
  • Reprocessing 2, RITER, medium.
  • Reprocessing 2, RITER, hard.
  • Reprocessing 2, RISE, cut in the r2p2 plot.
  • Reprocessing 3, RITER, soft.
  • Reprocessing 3, RITER, medium.
  • Reprocessing 3, RITER, hard.
  • Reprocessing 3, new algorithm, selection criteria and efficiency under study.

    Examples from reproc. 3: Efficiency/fake probability plots for the medium (open circles) and hard (full circles) identification levels.

    Daniel Peralta has provided a user friendly identification routine which combines likelihood values from both reconstruction algorithms, the track based and the stand-alone.

    PID for the single lepton working group

    More information on the particle identification alogorithms



    RICH detector paper draft