class AliPHOSPIDv0: public AliPHOSPID

 Implementation version v0 of the PHOS particle identifier
 Particle identification based on the
     - CPV information,
     - Preshower information (in MIXT or GPS2 geometries)
     - shower width.

 CPV or Preshower clusters should be closer in PHOS plane than fCpvEmcDistance (in cm).
 This parameter can be set by method SetCpvtoEmcDistanceCut(Float_t cut)

 One can set desirable ID method by the function SetIdentificationMethod(option).
 Presently the following options can be used together or separately :
     - "disp": use dispersion cut on shower width
               (width can be set by method SetDispersionCut(Float_t cut)
     - "ell" : use cut on the axis of the ellipse, drawn around shower
       (this cut can be changed by SetShowerProfileCut(char* formula),
        where formula - any function of two variables f(lambda[0],lambda[1]).
        Shower is considered as EM if f() > 0 )
 One can visualize current cuts calling method PlotDispersionCuts().

 use case:
  root [0] AliPHOSPIDv0 * p1 = new AliPHOSPIDv0("galice.root")
  Warning in <TDatabasePDG::TDatabasePDG>: object already instantiated
  root [1] p1->SetIdentificationMethod("disp ellipse")
  root [2] p1->ExecuteTask()
  root [3] AliPHOSPIDv0 * p2 = new AliPHOSPIDv0("galice1.root","ts1")
  Warning in <TDatabasePDG::TDatabasePDG>: object already instantiated
                // reading headers from file galice1.root and TrackSegments
                // with title "ts1"
  root [4] p2->SetRecParticlesBranch("rp1")
                // set file name for the branch RecParticles
  root [5] p2->ExecuteTask("deb all time")
                // available options
                // "deb" - prints # of reconstructed particles
                // "deb all" -  prints # and list of RecParticles
                // "time" - prints benchmarking results

*-- Author: Yves Schutz (SUBATECH)  & Gines Martinez (SUBATECH) &
            Dmitri Peressounko (SUBATECH & Kurchatov Institute)
            Completely redesined by Dmitri Peressounko, March 2001