class HParticleBtRing: public TObject

_HADES_CLASS_DESCRIPTION


  HParticleBtRing

  In this container all ring identification output provided by RICH
  backtracking is stored. HParticleCand::getRichBTInd() returns the
  ID to identify the corresponding backtracking container.
  -1 is returned if no backtracking information is provided.
  Only  tracks that fulfill the criteria of the track selection
  function and have at least one fired pad are stored. Track Fragments
  used for shared maxima information are only calculated in 4 degree range
  around good particle candidate with backtracking hits.






    Track selection function for lepton candidates



    Bool_t selectEpEm = kFALSE;
    if(pcand->isFlagAND(4,
			Particle::kIsAcceptedHitInnerMDC,
			Particle::kIsAcceptedHitOuterMDC,
			Particle::kIsAcceptedHitMETA,
			Particle::kIsAcceptedRK)&&

       pcand->getInnerSegmentChi2() > 0
       &&
       isGoodLepton(pcand)
       &&
       ( (sys == 0 && beta > 0.95) || (sys == 1 && beta > 0.93) )
        &&
       (MDCdEdx < 10)
       &&
       pcand->getChi2() < 1000) selectEpEm=kTRUE;
       )
           return kTRUE;
       else
	     return kFALSE;




  Example


    HCategory* btCat = (HCategory*)HCategoryManager::getCategory(catParticleBtRing);
    HParticleBtRing*     btRing;
    btRing = HCategoryManager::getObject(btRing,btCat,pcand1->getRichBTInd());
    btRing->getMaxima();
    btRing->getMaximaSharedTrack(pcand2->getIndex());



  Hints for usage

  Good Rings have at least 2 Maxima  and even more PadsRing. There are also
  rings with 1 Maxima, but this data sample is dominated by noise and will
  be unefficient to suppress large numbers of pions. Thresholds on other
  observables can be used to improve hadron suppression.
  Shared maxima are useful to identify overlapping rings from close pairs
  and hadronic tracks which pick up charge from good rings.




  Output variables:


  PadsRing:   Number of pads with good charge (q>65) on ring prediction area.
  PadsSum:    Number of all pads from clusters with at least one pad on ring.
              prediction area.
  ChargeRing: Charge of pads with good charge (q>65) on ring prediction area.
  ChargeSum:  Charge of all pads from clusters with at least one pad on ring
              prediction area.

  Clusters:     Number of clusters with at least one pad on ring prediction area.
  Maxima:       Number of maxima from contributing clusters inside 6 sigma area.
  MaximaCharge: Sum of charge of all maxima pads contributing clusters inside 6 sigma area.
  NearbyMaxima: Number of maxima from contributing clusters inside 3 sigma area.

  Chi2:       Ring quality based on maxima position.
  MeanDist:   Shift of ring center which minimizes Chi2 value
  RingMatrix: Charge of  pads matching with the ring prediction region divided by the charge of all pads in
              pad region with a radius of 8 pads around ring center.

  MaximaShared:                Number of maxima shared with other tracks.
  MaximaSharedFragement:      Number of maxima shared with other track Fragments in 4 degree
                               area around particle candidate
  MaximaChargeShared:          Sum  charge of all maxima pads that is shared other tracks.
  MaximaChargeSharedFragment: Sum  charge of all maxima pads that is shared with other
                               track fragments in 4 degree area around ring.
  NearbyMaximaShared:          Number of nearby maxima shared with other tracks.


  MaximaSharedTrack:          Number of maxima shared with one specific track.
                              HParticleCand index is needed as input value.
  MaximaSharedFragmentTrack: Number of maxima shared with one specific track fragment in
                              4 degree area around ring.
                              HParticleCand index is needed as input value.
  MaximaChargeSharedTrack:    Sum  charge of all maxima pads that is with one specific track.
                              HParticleCand index is needed as input value.
  MaximaChargeSharedFragmentTrack: Sum  charge of all maxima pads that is with one specific
                              track fragment in 4 degree area around ring.
                              HParticleCand index is needed as input value.

  NearbyMaximaSharedTrack: Number of nearby maxima shared with one specific track.
                           HParticleCand index is needed as input value.