MUON/AliMUONClusterFinderSimpleFit.cxx

   1 /**************************************************************************
   2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   3 *                                                                        *
   4 * Author: The ALICE Off-line Project.                                    *
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  10 * copies and that both the copyright notice and this permission notice   *
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  12 * about the suitability of this software for any purpose. It is          *
  13 * provided "as is" without express or implied warranty.                  *
  14 **************************************************************************/
  15
  16 // $Id$
  17
  18 #include "AliMUONClusterFinderSimpleFit.h"
  19
  20 #include "AliLog.h"
  21 #include "AliMpDEManager.h"
  22 #include "AliMUONCluster.h"
  23 #include "AliMUONConstants.h"
  24 #include "AliMUONVDigit.h"
  25 #include "AliMUONMathieson.h"
  26 #include "AliMUONPad.h"
  27 #include "AliMpArea.h"
  28 #include "TObjArray.h"
  29 #include "TVector2.h"
  30 #include "TVirtualFitter.h"
  31 #include "TF1.h"
  32 #include "AliMUONVDigitStore.h"
  33 #include <Riostream.h>
  34
  35 //-----------------------------------------------------------------------------
  36 /// \class AliMUONClusterFinderSimpleFit
  37 ///
  38 /// Basic cluster finder
  39 ///
  40 /// We simply use AliMUONPreClusterFinder to get basic cluster,
  41 /// and then we try to fit the charge repartition using a Mathieson
  42 /// distribution, varying the position.
  43 ///
  44 /// FIXME: this one is still at the developping stage...
  45 ///
  46 /// \author Laurent Aphecetche
  47 //-----------------------------------------------------------------------------
  48
  49 /// \cond CLASSIMP
  50 ClassImp(AliMUONClusterFinderSimpleFit)
  51 /// \endcond
  52
  53 namespace
  54 {
  55   //___________________________________________________________________________
  56   void
  57   FitFunction(Int_t& /*notused*/, Double_t* /*notused*/,
  58               Double_t& f, Double_t* par,
  59               Int_t /*notused*/)
  60   {
  61     /// Chi2 Function to minimize: Mathieson charge distribution in 2 dimensions
  62
  63     TObjArray* userObjects = static_cast<TObjArray*>(TVirtualFitter::GetFitter()->GetObjectFit());
  64
  65     AliMUONCluster* cluster = static_cast<AliMUONCluster*>(userObjects->At(0));
  66     AliMUONMathieson* mathieson = static_cast<AliMUONMathieson*>(userObjects->At(1));
  67
  68     f = 0.0;
  69     Float_t qTot = cluster->Charge();
  70 //    Float_t chargeCorrel[] = { cluster->Charge(0)/qTot, cluster->Charge(1)/qTot };
  71 //    Float_t qRatio[] = { 1.0/par[2], par[2] };
  72
  73     for ( Int_t i = 0 ; i < cluster->Multiplicity(); ++i )
  74     {
  75       AliMUONPad* pad = cluster->Pad(i);
  76       // skip pads w/ saturation or other problem(s)
  77       if ( pad->Status() ) continue;
  78       TVector2 lowerLeft = TVector2(par[0],par[1]) - pad->Position() - pad->Dimensions();
  79       TVector2 upperRight(lowerLeft + pad->Dimensions()*2.0);
  80       Float_t estimatedCharge = mathieson->IntXY(lowerLeft.X(),lowerLeft.Y(),
  81                                                  upperRight.X(),upperRight.Y());
  82 //      estimatedCharge *= 2/(1+qRatio[pad->Cathode()]);
  83       Float_t actualCharge = pad->Charge()/qTot;
  84
  85       Float_t delta = (estimatedCharge - actualCharge);
  86
  87       f += delta*delta;
  88     }
  89   }
  90 }
  91
  92 //_____________________________________________________________________________
  93 AliMUONClusterFinderSimpleFit::AliMUONClusterFinderSimpleFit(AliMUONVClusterFinder* clusterFinder)
  94 : AliMUONVClusterFinder(),
  95 fClusterFinder(clusterFinder),
  96 fMathieson(0x0),
  97 fLowestClusterCharge(0)
  98 {
  99   /// ctor
 100 }
 101
 102 //_____________________________________________________________________________
 103 AliMUONClusterFinderSimpleFit::~AliMUONClusterFinderSimpleFit()
 104 {
 105   /// dtor
 106   delete fClusterFinder;
 107   delete fMathieson;
 108 }
 109
 110 //_____________________________________________________________________________
 111 Bool_t
 112 AliMUONClusterFinderSimpleFit::Prepare(Int_t detElemId,
 113                                        TObjArray* pads[2],
 114                                        const AliMpArea& area)
 115 {
 116   /// Prepare for clustering
 117
 118   // FIXME: should we get the Mathieson from elsewhere ?
 119
 120   // Find out the DetElemId
 121   AliMq::Station12Type stationType = AliMpDEManager::GetStation12Type(detElemId);
 122
 123   Float_t kx3 = AliMUONConstants::SqrtKx3();
 124   Float_t ky3 = AliMUONConstants::SqrtKy3();
 125   Float_t pitch = AliMUONConstants::Pitch();
 126
 127   if ( stationType == AliMq::kStation1 )
 128   {
 129     kx3 = AliMUONConstants::SqrtKx3St1();
 130     ky3 = AliMUONConstants::SqrtKy3St1();
 131     pitch = AliMUONConstants::PitchSt1();
 132   }
 133
 134   delete fMathieson;
 135   fMathieson = new AliMUONMathieson;
 136
 137   fMathieson->SetPitch(pitch);
 138   fMathieson->SetSqrtKx3AndDeriveKx2Kx4(kx3);
 139   fMathieson->SetSqrtKy3AndDeriveKy2Ky4(ky3);
 140
 141   return fClusterFinder->Prepare(detElemId,pads,area);
 142 }
 143
 144 //_____________________________________________________________________________
 145 AliMUONCluster*
 146 AliMUONClusterFinderSimpleFit::NextCluster()
 147 {
 148   /// Returns next cluster
 149
 150   if ( !fClusterFinder ) return 0x0;
 151   AliMUONCluster* cluster = fClusterFinder->NextCluster();
 152   if ( cluster )
 153   {
 154     ComputePosition(*cluster);
 155
 156     if ( cluster->Charge() < fLowestClusterCharge )
 157     {
 158       // skip that one
 159       return NextCluster();
 160     }
 161   }
 162   return cluster;
 163 }
 164
 165 //_____________________________________________________________________________
 166 void
 167 AliMUONClusterFinderSimpleFit::ComputePosition(AliMUONCluster& cluster)
 168 {
 169   /// Compute the position of the given cluster, by fitting a Mathieson
 170   /// charge distribution to it
 171
 172   TVirtualFitter* fitter = TVirtualFitter::Fitter(0,2);
 173   fitter->SetFCN(FitFunction);
 174
 175   if ( cluster.Multiplicity() < 3 ) return;
 176
 177   // We try a Mathieson fit, starting
 178   // with the center-of-gravity estimate as a first guess
 179   // for the cluster center.
 180
 181   Double_t xCOG = cluster.Position().X();
 182   Double_t yCOG = cluster.Position().Y();
 183
 184   Float_t stepX = 0.01; // cm
 185   Float_t stepY = 0.01; // cm
 186
 187   Double_t arg(-1); // disable printout
 188
 189   fitter->ExecuteCommand("SET PRINT",&arg,1);
 190
 191   fitter->SetParameter(0,"cluster X position",xCOG,stepX,0,0);
 192   fitter->SetParameter(1,"cluster Y position",yCOG,stepY,0,0);
 193
 194   TObjArray userObjects;
 195
 196   userObjects.Add(&cluster);
 197   userObjects.Add(fMathieson);
 198
 199   fitter->SetObjectFit(&userObjects);
 200
 201   Int_t val = fitter->ExecuteCommand("MIGRAD",0,0);
 202   AliDebug(1,Form("ExecuteCommand returned value=%d",val));
 203   if ( val )
 204   {
 205     // fit failed. Using COG results, with big errors
 206     AliWarning("Fit failed. Using COG results for cluster=");
 207     StdoutToAliWarning(cluster.Print());
 208     cluster.SetPosition(TVector2(xCOG,yCOG),TVector2(TMath::Abs(xCOG),TMath::Abs(yCOG)));
 209     cluster.SetChi2(1E3);
 210   }
 211
 212   Double_t results[] = { fitter->GetParameter(0),
 213     fitter->GetParameter(1) };
 214
 215   Double_t errors[] = { fitter->GetParError(0),
 216     fitter->GetParError(1) };
 217
 218   cluster.SetPosition(TVector2(results[0],results[1]),
 219                       TVector2(errors[0],errors[1]));
 220
 221   Double_t amin, edm, errdef;
 222   Int_t nvpar, nparx;
 223
 224   fitter->GetStats(amin, edm, errdef, nvpar, nparx);
 225
 226   Double_t chi2 = amin;
 227
 228   AliDebug(1,Form("Cluster fitted to (x,y)=(%e,%e) (xerr,yerr)=(%e,%e) \n chi2=%e ndf=%d",
 229                   results[0],results[1],
 230                   errors[0],errors[1],chi2,fitter->GetNumberFreeParameters()));
 231   cluster.SetChi2(chi2);
 232 }
 233
 234
 235