]> git.uio.no Git - u/mrichter/AliRoot.git/blobdiff - FMD/AliFMDReconstructor.cxx
public conctructor to avoid complains during digitzation
[u/mrichter/AliRoot.git] / FMD / AliFMDReconstructor.cxx
index c9dec1691fed377913ca2b02c97b952e31d4cc51..acf44e3f102004b15ce631615a2dda39ac6af5f9 100644 (file)
  * about the suitability of this software for any purpose. It is          *
  * provided "as is" without express or implied warranty.                  *
  **************************************************************************/
-
 /* $Id$ */
-
+/** @file    AliFMDReconstructor.cxx
+    @author  Christian Holm Christensen <cholm@nbi.dk>
+    @date    Mon Mar 27 12:47:09 2006
+    @brief   FMD reconstruction 
+*/
 //____________________________________________________________________
 //
-// This is a class that constructs AliFMDMult (reconstructed
-// multiplicity) from of Digits
-//
-// This class reads either digits from a TClonesArray or raw data from
+// This is a class that constructs AliFMDRecPoint objects from of Digits
+// This class reads either digits from a TClonesArray or raw data from 
 // a DDL file (or similar), and stores the read ADC counts in an
-// internal cache (fAdcs). 
-//
-// From the cached values it then calculates the number of particles
-// that hit a region of the FMDs, as specified by the user. 
-//
-// The reconstruction can be done in two ways: Either via counting the
-// number of empty strips (Poisson method), or by converting the ADC
-// signal to an energy deposition, and then dividing by the typical
-// energy loss of a particle.
-// 
-//      +---------------------+       +---------------------+
-//      | AliFMDReconstructor |<>-----| AliFMDMultAlgorithm |
-//      +---------------------+       +---------------------+
-//                                               ^
-//                                               |
-//                                   +-----------+---------+
-//                                   |                     |
-//                         +-------------------+   +------------------+
-//                         | AliFMDMultPoisson |   | AliFMDMultNaiive |
-//                         +-------------------+   +------------------+
-//
-// AliFMDReconstructor acts as a manager class.  It contains a list of
-// AliFMDMultAlgorithm objects.  The call graph looks something like 
+// internal cache (fAdcs).   The rec-points are made via the naiive
+// method. 
 //
-//
-//       +----------------------+            +----------------------+
-//       | :AliFMDReconstructor |            | :AliFMDMultAlgorithm |
-//       +----------------------+            +----------------------+
-//                  |                                  |
-//    Reconstruct  +-+                                 |
-//    ------------>| |                         PreRun +-+
-//                 | |------------------------------->| |   
-//                 | |                                +-+
-//                 | |-----+ (for each event)          |
-//                 | |     | *ProcessEvent             |
-//                 |+-+    |                           |
-//                 || |<---+                 PreEvent +-+
-//                 || |------------------------------>| |      
-//                 || |                               +-+
-//                 || |-----+                          |
-//                 || |     | ProcessDigits            |
-//                 ||+-+    |                          |
-//                 ||| |<---+                          |
-//                 ||| |         *ProcessDigit(digit) +-+
-//                 ||| |----------------------------->| |
-//                 ||| |                              +-+
-//                 ||+-+                               |
-//                 || |                     PostEvent +-+
-//                 || |------------------------------>| |
-//                 || |                               +-+
-//                 |+-+                                |
-//                 | |                        PostRun +-+
-//                 | |------------------------------->| |
-//                 | |                                +-+
-//                 +-+                                 |
-//                  |                                  |
-//
-//
-// 
 //-- Authors: Evgeny Karpechev(INR) and Alla Maevsksia
 //  Latest changes by Christian Holm Christensen <cholm@nbi.dk>
 //
 //
 //____________________________________________________________________
 
-#include <AliLog.h>                        // ALILOG_H
-#include <AliRun.h>                        // ALIRUN_H
-#include <AliRunLoader.h>                  // ALIRUNLOADER_H
-#include <AliLoader.h>                     // ALILOADER_H
-#include <AliHeader.h>                     // ALIHEADER_H
-#include <AliRawReader.h>                  // ALIRAWREADER_H
-#include <AliGenEventHeader.h>             // ALIGENEVENTHEADER_H
-#include "AliFMD.h"                       // ALIFMD_H
+// #include <AliLog.h>                        // ALILOG_H
+// #include <AliRun.h>                        // ALIRUN_H
+#include "AliFMDDebug.h"
 #include "AliFMDGeometry.h"                // ALIFMDGEOMETRY_H
 #include "AliFMDParameters.h"              // ALIFMDPARAMETERS_H
-#include "AliFMDDetector.h"                // ALIFMDDETECTOR_H
-#include "AliFMDRing.h"                    // ALIFMDRING_H
 #include "AliFMDDigit.h"                   // ALIFMDDIGIT_H
 #include "AliFMDReconstructor.h"           // ALIFMDRECONSTRUCTOR_H
-#include "AliFMDRawStream.h"               // ALIFMDRAWSTREAM_H
 #include "AliFMDRawReader.h"               // ALIFMDRAWREADER_H
-#include "AliFMDMultAlgorithm.h"          // ALIFMDMULTALGORITHM_H
-#include "AliFMDMultPoisson.h"            // ALIFMDMULTPOISSON_H
-#include "AliFMDMultNaiive.h"             // ALIFMDMULTNAIIVE_H
+#include "AliFMDRecPoint.h"               // ALIFMDMULTNAIIVE_H
+#include "AliESDEvent.h"                  // ALIESDEVENT_H
+#include "AliESDVertex.h"                 // ALIESDVERTEX_H
+#include <AliESDFMD.h>                    // ALIESDFMD_H
+#include <TMath.h>
+#include <TH1.h>
+#include <TH2.h>
+#include <TFile.h>
+class AliRawReader;
 
 //____________________________________________________________________
 ClassImp(AliFMDReconstructor)
@@ -116,40 +59,48 @@ ClassImp(AliFMDReconstructor)
 //____________________________________________________________________
 AliFMDReconstructor::AliFMDReconstructor() 
   : AliReconstructor(),
-    fPedestal(0), 
-    fPedestalWidth(0),
-    fPedestalFactor(0)
+    fMult(0x0), 
+    fNMult(0),
+    fTreeR(0x0),
+    fCurrentVertex(0),
+    fESDObj(0x0),
+    fNoiseFactor(0),
+    fAngleCorrect(kTRUE),
+    fVertexType(kNoVertex),
+    fESD(0x0),
+    fDiagnostics(kFALSE),
+    fDiagStep1(0), 
+    fDiagStep2(0),
+    fDiagStep3(0),
+    fDiagStep4(0),
+    fDiagAll(0)
 {
-  // Make a new FMD reconstructor object - default CTOR.
-  AliFMDParameters* pars = AliFMDParameters::Instance();
-  fPedestal       = pars->GetPedestal();
-  fPedestalWidth  = pars->GetPedestalWidth();
-  fPedestalFactor = pars->GetPedestalFactor();
-  
-  fAlgorithms.Add(new AliFMDMultNaiive);
-  fAlgorithms.Add(new AliFMDMultPoisson);
+  // Make a new FMD reconstructor object - default CTOR.  
+  SetNoiseFactor();
+  SetAngleCorrect();
 }
   
 
 //____________________________________________________________________
 AliFMDReconstructor::AliFMDReconstructor(const AliFMDReconstructor& other) 
-  : AliReconstructor(),
-    fPedestal(0), 
-    fPedestalWidth(0),
-    fPedestalFactor(0)
+  : AliReconstructor(), 
+    fMult(other.fMult),
+    fNMult(other.fNMult),
+    fTreeR(other.fTreeR),
+    fCurrentVertex(other.fCurrentVertex),
+    fESDObj(other.fESDObj),
+    fNoiseFactor(other.fNoiseFactor),
+    fAngleCorrect(other.fAngleCorrect),
+    fVertexType(other.fVertexType),
+    fESD(other.fESD),
+    fDiagnostics(other.fDiagnostics),
+    fDiagStep1(other.fDiagStep1), 
+    fDiagStep2(other.fDiagStep2),
+    fDiagStep3(other.fDiagStep3),
+    fDiagStep4(other.fDiagStep4),
+    fDiagAll(other.fDiagAll) 
 {
   // Copy constructor 
-  fPedestal       = other.fPedestal;
-  fPedestalWidth  = other.fPedestalWidth;
-  fPedestalFactor = other.fPedestalFactor;
-
-  
-  fAlgorithms.Delete();
-  TIter next(&(other.fAlgorithms));
-  AliFMDMultAlgorithm* algorithm = 0;
-  while ((algorithm = static_cast<AliFMDMultAlgorithm*>(next()))) 
-    fAlgorithms.Add(algorithm);
-  fAlgorithms.SetOwner(kFALSE);
 }
   
 
@@ -158,17 +109,21 @@ AliFMDReconstructor&
 AliFMDReconstructor::operator=(const AliFMDReconstructor& other) 
 {
   // Assignment operator
-  fPedestal       = other.fPedestal;
-  fPedestalWidth  = other.fPedestalWidth;
-  fPedestalFactor = other.fPedestalFactor;
-
-  fAlgorithms.Delete();
-  TIter next(&(other.fAlgorithms));
-  AliFMDMultAlgorithm* algorithm = 0;
-  while ((algorithm = static_cast<AliFMDMultAlgorithm*>(next()))) 
-    fAlgorithms.Add(algorithm);
-  fAlgorithms.SetOwner(kFALSE);
-
+  fMult          = other.fMult;
+  fNMult         = other.fNMult;
+  fTreeR         = other.fTreeR;
+  fCurrentVertex = other.fCurrentVertex;
+  fESDObj        = other.fESDObj;
+  fNoiseFactor   = other.fNoiseFactor;
+  fAngleCorrect  = other.fAngleCorrect;
+  fVertexType    = other.fVertexType;
+  fESD           = other.fESD;
+  fDiagnostics   = other.fDiagnostics;
+  fDiagStep1     = other.fDiagStep1;
+  fDiagStep2     = other.fDiagStep2;
+  fDiagStep3     = other.fDiagStep3;
+  fDiagStep4     = other.fDiagStep4;
+  fDiagAll       = other.fDiagAll;
   return *this;
 }
 
@@ -176,35 +131,61 @@ AliFMDReconstructor::operator=(const AliFMDReconstructor& other)
 AliFMDReconstructor::~AliFMDReconstructor() 
 {
   // Destructor 
-  fAlgorithms.Delete();
+  if (fMult)   fMult->Delete();
+  if (fMult)   delete fMult;
+  if (fESDObj) delete fESDObj;
 }
 
 //____________________________________________________________________
 void 
-AliFMDReconstructor::Init(AliRunLoader* runLoader
+AliFMDReconstructor::Init() 
 {
   // Initialize the reconstructor 
-  AliDebug(1, Form("Init called with runloader 0x%x", runLoader));
+
+  // Initialize the geometry 
+  AliFMDGeometry* geom = AliFMDGeometry::Instance();
+  geom->Init();
+  geom->InitTransformations();
+
+  // Initialize the parameters
+  AliFMDParameters* param = AliFMDParameters::Instance();
+  param->Init();
+  
+  // Current vertex position
   fCurrentVertex = 0;
-  if (!runLoader) { 
-    Warning("Init", "No run loader");
-    return;
-  }
-  AliHeader* header = runLoader->GetHeader();
-  if (!header) {
-    Warning("Init", "No header");
-    return;
-  }
-  AliGenEventHeader* eventHeader = header->GenEventHeader();
-  if (!eventHeader) {
-    Warning("Init", "no event header");
-    return;
-  }
-  TArrayF vtx;
-  eventHeader->PrimaryVertex(vtx);
-  fCurrentVertex = vtx[2];
-  AliDebug(1, Form("Primary vertex Z coordinate for event # %d/%d is %f", 
-                  header->GetRun(), header->GetEvent(), fCurrentVertex));
+  // Create array of reconstructed strip multiplicities 
+  fMult = new TClonesArray("AliFMDRecPoint", 51200);
+  // Create ESD output object 
+  fESDObj = new AliESDFMD;
+  
+  // Check if we need diagnostics histograms 
+  if (!fDiagnostics) return;
+  fDiagStep1   = new TH2I("diagStep1", "Read ADC vs. Noise surpressed ADC",
+                       1024, -.5, 1023.5, 1024, -.5, 1023.5);
+  fDiagStep1->SetDirectory(0);
+  fDiagStep1->GetXaxis()->SetTitle("ADC (read)");
+  fDiagStep1->GetYaxis()->SetTitle(Form("ADC (noise surpressed %4.f)", 
+                                       fNoiseFactor));
+  fDiagStep2  = new TH2F("diagStep2",  "ADC vs Edep deduced",
+                       1024, -.5, 1023.5, 100, 0, 2);
+  fDiagStep2->SetDirectory(0);
+  fDiagStep2->GetXaxis()->SetTitle("ADC (noise surpressed)");
+  fDiagStep2->GetYaxis()->SetTitle("#Delta E [GeV]");
+  fDiagStep3  = new TH2F("diagStep3",  "Edep vs Edep path corrected",
+                       100, 0., 2., 100, 0., 2.);
+  fDiagStep3->SetDirectory(0);
+  fDiagStep3->GetXaxis()->SetTitle("#Delta E [GeV]");
+  fDiagStep3->GetYaxis()->SetTitle("#Delta E/#Delta x #times #delta x [GeV]");
+  fDiagStep4  = new TH2F("diagStep4",  "Edep vs Multiplicity deduced", 
+                       100, 0., 2., 100, -.1, 19.9);
+  fDiagStep4->SetDirectory(0);
+  fDiagStep4->GetXaxis()->SetTitle("#Delta E/#Delta x #times #delta x [GeV]");
+  fDiagStep4->GetYaxis()->SetTitle("Multiplicity");
+  fDiagAll    = new TH2F("diagAll",    "Read ADC vs Multiplicity deduced", 
+                        1024, -.5, 1023.5, 100, -.1, 19.9);
+  fDiagAll->SetDirectory(0);
+  fDiagAll->GetXaxis()->SetTitle("ADC (read)");
+  fDiagAll->GetYaxis()->SetTitle("Multiplicity");
 }
 
 //____________________________________________________________________
@@ -213,11 +194,54 @@ AliFMDReconstructor::ConvertDigits(AliRawReader* reader,
                                   TTree* digitsTree) const
 {
   // Convert Raw digits to AliFMDDigit's in a tree 
+  AliFMDDebug(2, ("Reading raw data into digits tree"));
   AliFMDRawReader rawRead(reader, digitsTree);
   // rawRead.SetSampleRate(fFMD->GetSampleRate());
   rawRead.Exec();
 }
 
+//____________________________________________________________________
+void 
+AliFMDReconstructor::GetVertex() const
+{
+  // Return the vertex to use. 
+  // This is obtained from the ESD object. 
+  // If not found, a warning is issued.
+  fVertexType    = kNoVertex;
+  fCurrentVertex = 0;
+  if (fESD) {
+    const AliESDVertex* vertex = fESD->GetVertex();
+    if (vertex) {
+      AliFMDDebug(2, ("Got vertex from ESD: %f", vertex->GetZv()));
+      fCurrentVertex = vertex->GetZv();
+      fVertexType    = kESDVertex;
+      return;
+    }
+  }
+  AliWarning("Didn't get any vertex from ESD or generator");
+}
+  
+
+//____________________________________________________________________
+void 
+AliFMDReconstructor::Reconstruct(AliRawReader* /*reader*/, TTree*) const
+{
+  // Reconstruct directly from raw data (no intermediate output on
+  // digit tree or rec point tree).  
+  // Parameters: 
+  //   reader  Raw event reader 
+  //   ctree    Not used. 
+  AliError("Method is not used");
+#if 0
+  TClonesArray*   array = new TClonesArray("AliFMDDigit");
+  AliFMDRawReader rawRead(reader, 0);
+  rawRead.ReadAdcs(array);
+  ProcessDigits(array);
+  array->Delete();
+  delete array;
+#endif
+}
+
 //____________________________________________________________________
 void 
 AliFMDReconstructor::Reconstruct(TTree* digitsTree, 
@@ -225,71 +249,102 @@ AliFMDReconstructor::Reconstruct(TTree* digitsTree,
 {
   // Reconstruct event from digits in tree 
   // Get the FMD branch holding the digits. 
-  AliDebug(1, "Reconstructing from digits in a tree");
-  
+  // FIXME: The vertex may not be known yet, so we may have to move
+  // some of this to FillESD. 
+  AliFMDDebug(2, ("Reconstructing from digits in a tree"));
+  GetVertex();
+
   TBranch *digitBranch = digitsTree->GetBranch("FMD");
-  TClonesArray* digits = new TClonesArray("AliFMDDigit");
   if (!digitBranch) {
     Error("Exec", "No digit branch for the FMD found");
     return;
   }
+  TClonesArray* digits = new TClonesArray("AliFMDDigit");
   digitBranch->SetAddress(&digits);
 
-  TIter next(&fAlgorithms);
-  AliFMDMultAlgorithm* algorithm = 0;
-  while ((algorithm = static_cast<AliFMDMultAlgorithm*>(next()))) 
-    algorithm->PreEvent(clusterTree, fCurrentVertex);
+  if (fMult)   fMult->Clear();
+  if (fESDObj) fESDObj->Clear();
+  
+  fNMult = 0;
+  fTreeR = clusterTree;
+  fTreeR->Branch("FMD", &fMult);
+  
+  AliFMDDebug(5, ("Getting entry 0 from digit branch"));
   digitBranch->GetEntry(0);
   
+  AliFMDDebug(5, ("Processing digits"));
   ProcessDigits(digits);
 
-  next.Reset();
-  algorithm = 0;
-  while ((algorithm = static_cast<AliFMDMultAlgorithm*>(next()))) 
-    algorithm->PostEvent();
-  clusterTree->Fill();
+  Int_t written = clusterTree->Fill();
+  AliFMDDebug(10, ("Filled %d bytes into cluster tree", written));
+  digits->Delete();
+  delete digits;
 }
  
+
 //____________________________________________________________________
 void
 AliFMDReconstructor::ProcessDigits(TClonesArray* digits) const
 {
+  // For each digit, find the pseudo rapdity, azimuthal angle, and
+  // number of corrected ADC counts, and pass it on to the algorithms
+  // used. 
   Int_t nDigits = digits->GetEntries();
-  AliDebug(1, Form("Got %d digits", nDigits));
+  AliFMDDebug(1, ("Got %d digits", nDigits));
+  fESDObj->SetNoiseFactor(fNoiseFactor);
+  fESDObj->SetAngleCorrected(fAngleCorrect);
   for (Int_t i = 0; i < nDigits; i++) {
     AliFMDDigit* digit = static_cast<AliFMDDigit*>(digits->At(i));
-    AliFMDGeometry* fmd = AliFMDGeometry::Instance();
-    AliFMDDetector* subDetector = fmd->GetDetector(digit->Detector());
-    if (!subDetector) { 
-      Warning("ProcessDigits", "Unknown detector: FMD%d" , digit->Detector());
+    AliFMDParameters* param  = AliFMDParameters::Instance();
+    // Check that the strip is not marked as dead 
+    if (param->IsDead(digit->Detector(), digit->Ring(), 
+                     digit->Sector(), digit->Strip())) {
+      AliFMDDebug(10, ("FMD%d%c[%2d,%3d] is dead", digit->Detector(), 
+                       digit->Ring(), digit->Sector(), digit->Strip()));
       continue;
     }
+
+    // digit->Print();
+    // Get eta and phi 
+    Float_t eta, phi;
+    PhysicalCoordinates(digit, eta, phi);
     
-    AliFMDRing* ring  = subDetector->GetRing(digit->Ring());
-    Float_t     ringZ = subDetector->GetRingZ(digit->Ring());
-    if (!ring) {
-      Warning("ProcessDigits", "Unknown ring: FMD%d%c", digit->Detector(), 
-             digit->Ring());
-      break;
-    }
-    
-    Float_t  realZ    = fCurrentVertex + ringZ;
-    Float_t  stripR   = ((ring->GetHighR() - ring->GetLowR()) 
-                        / ring->GetNStrips() * (digit->Strip() + .5) 
-                        + ring->GetLowR());
-    Float_t  theta    = TMath::ATan2(stripR, realZ);
-    Float_t  phi      = (2 * TMath::Pi() / ring->GetNSectors() 
-                        * (digit->Sector() + .5));
-    Float_t  eta      = -TMath::Log(TMath::Tan(theta / 2));
+    // Substract pedestal. 
     UShort_t counts   = SubtractPedestal(digit);
     
-    TIter next(&fAlgorithms);
-    AliFMDMultAlgorithm* algorithm = 0;
-    while ((algorithm = static_cast<AliFMDMultAlgorithm*>(next()))) 
-      algorithm->ProcessDigit(digit, eta, phi, counts);
+    // Gain match digits. 
+    Double_t edep     = Adc2Energy(digit, eta, counts);
+    
+    // Make rough multiplicity 
+    Double_t mult     = Energy2Multiplicity(digit, edep);
+    
+    AliFMDDebug(10, ("FMD%d%c[%2d,%3d]: "
+                     "ADC: %d, Counts: %d, Energy: %f, Mult: %f", 
+                     digit->Detector(), digit->Ring(), digit->Sector(),
+                     digit->Strip(), digit->Counts(), counts, edep, mult));
+    
+    // Create a `RecPoint' on the output branch. 
+    if (fMult) {
+      AliFMDRecPoint* m = 
+       new ((*fMult)[fNMult]) AliFMDRecPoint(digit->Detector(), 
+                                             digit->Ring(), 
+                                             digit->Sector(),
+                                             digit->Strip(),
+                                             eta, phi, 
+                                             edep, mult);
+      (void)m; // Suppress warnings about unused variables. 
+      fNMult++;
+    }
+    
+    fESDObj->SetMultiplicity(digit->Detector(), digit->Ring(), 
+                            digit->Sector(),  digit->Strip(), mult);
+    fESDObj->SetEta(digit->Detector(), digit->Ring(), 
+                   digit->Sector(),  digit->Strip(), eta);
+
+    if (fDiagAll) fDiagAll->Fill(digit->Counts(), mult);  
   }
 }
-      
+
 //____________________________________________________________________
 UShort_t
 AliFMDReconstructor::SubtractPedestal(AliFMDDigit* digit) const
@@ -299,23 +354,181 @@ AliFMDReconstructor::SubtractPedestal(AliFMDDigit* digit) const
   // load this to subtract a pedestal that was given in a database or
   // something like that. 
 
-  Int_t counts = 0;
-  Float_t ped = fPedestal + fPedestalFactor * fPedestalWidth;
-  if (digit->Count3() > 0)      counts = digit->Count3();
-  else if (digit->Count2() > 0) counts = digit->Count2();
-  else                          counts = digit->Count1();
-  counts = TMath::Max(Int_t(counts - ped), 0);
+  Int_t             counts = 0;
+  Int_t             adc    = 0;
+  AliFMDParameters* param  = AliFMDParameters::Instance();
+  Float_t           ped    = param->GetPedestal(digit->Detector(), 
+                                               digit->Ring(), 
+                                               digit->Sector(), 
+                                               digit->Strip());
+  Float_t           noise  = param->GetPedestalWidth(digit->Detector(), 
+                                                    digit->Ring(), 
+                                                    digit->Sector(), 
+                                                    digit->Strip());
+  AliFMDDebug(15, ("Subtracting pedestal %f from signal %d", 
+                  ped, digit->Counts()));
+  if (digit->Count3() > 0)      adc = digit->Count3();
+  else if (digit->Count2() > 0) adc = digit->Count2();
+  else                          adc = digit->Count1();
+  counts = TMath::Max(Int_t(adc - ped), 0);
+  if (counts < noise * fNoiseFactor) counts = 0;
+  if (counts > 0) AliFMDDebug(15, ("Got a hit strip"));
+  if (fDiagStep1) fDiagStep1->Fill(adc, counts);
+  
   return  UShort_t(counts);
 }
 
+//____________________________________________________________________
+Float_t
+AliFMDReconstructor::Adc2Energy(AliFMDDigit* digit, 
+                               Float_t      eta, 
+                               UShort_t     count) const
+{
+  // Converts number of ADC counts to energy deposited. 
+  // Note, that this member function can be overloaded by derived
+  // classes to do strip-specific look-ups in databases or the like,
+  // to find the proper gain for a strip. 
+  // 
+  // In this simple version, we calculate the energy deposited as 
+  // 
+  //    EnergyDeposited = cos(theta) * gain * count
+  // 
+  // where 
+  // 
+  //           Pre_amp_MIP_Range
+  //    gain = ----------------- * Energy_deposited_per_MIP
+  //           ADC_channel_size    
+  // 
+  // is constant and the same for all strips.
+  if (count <= 0) return 0;
+  AliFMDParameters* param = AliFMDParameters::Instance();
+  Float_t           gain  = param->GetPulseGain(digit->Detector(), 
+                                               digit->Ring(), 
+                                               digit->Sector(), 
+                                               digit->Strip());
+  AliFMDDebug(15, ("Converting counts %d to energy via factor %f", 
+                   count, gain));
+
+  Double_t edep  = count * gain;
+  if (fDiagStep2) fDiagStep2->Fill(count, edep);  
+  if (fAngleCorrect) {
+    Double_t theta = 2 * TMath::ATan(TMath::Exp(-eta));
+    Double_t corr  = TMath::Abs(TMath::Cos(theta));
+    Double_t cedep = corr * edep;
+    AliFMDDebug(10, ("correcting for path %f * %f = %f (eta=%f, theta=%f)",
+                     edep, corr, cedep, eta, theta));
+    if (fDiagStep3) fDiagStep3->Fill(edep, cedep);  
+    edep = cedep;
+  }
+  return edep;
+}
+
+//____________________________________________________________________
+Float_t
+AliFMDReconstructor::Energy2Multiplicity(AliFMDDigit* /* digit */, 
+                                        Float_t      edep) const
+{
+  // Converts an energy signal to number of particles. 
+  // Note, that this member function can be overloaded by derived
+  // classes to do strip-specific look-ups in databases or the like,
+  // to find the proper gain for a strip. 
+  // 
+  // In this simple version, we calculate the multiplicity as 
+  // 
+  //   multiplicity = Energy_deposited / Energy_deposited_per_MIP
+  // 
+  // where 
+  //
+  //   Energy_deposited_per_MIP = 1.664 * SI_density * SI_thickness 
+  // 
+  // is constant and the same for all strips 
+  AliFMDParameters* param   = AliFMDParameters::Instance();
+  Double_t          edepMIP = param->GetEdepMip();
+  Float_t           mult    = edep / edepMIP;
+  if (edep > 0) 
+    AliFMDDebug(15, ("Translating energy %f to multiplicity via "
+                    "divider %f->%f", edep, edepMIP, mult));
+  if (fDiagStep4) fDiagStep4->Fill(edep, mult);  
+  return mult;
+}
+
+//____________________________________________________________________
+void
+AliFMDReconstructor::PhysicalCoordinates(AliFMDDigit* digit, 
+                                        Float_t& eta, 
+                                        Float_t& phi) const
+{
+  // Get the eta and phi of a digit 
+  // 
+  // Get geometry. 
+  AliFMDGeometry* geom = AliFMDGeometry::Instance();
+  Double_t x, y, z, r, theta;
+  geom->Detector2XYZ(digit->Detector(), digit->Ring(), digit->Sector(), 
+                   digit->Strip(), x, y, z);
+  // Correct for vertex offset. 
+  z     += fCurrentVertex;
+  phi   =  TMath::ATan2(y, x);
+  r     =  TMath::Sqrt(y * y + x * x);
+  theta =  TMath::ATan2(r, z);
+  eta   = -TMath::Log(TMath::Tan(theta / 2));
+}
+
+      
+
 //____________________________________________________________________
 void 
 AliFMDReconstructor::FillESD(TTree*  /* digitsTree */, 
                             TTree*  /* clusterTree */,
-                            AliESD* /* esd*/) const
+                            AliESDEvent* esd) const
 {
   // nothing to be done
+  // FIXME: The vertex may not be known when Reconstruct is executed,
+  // so we may have to move some of that member function here. 
+  AliFMDDebug(2, ("Calling FillESD with two trees and one ESD"));
+  // fESDObj->Print();
+
+  if (esd) { 
+    AliFMDDebug(2, ("Writing FMD data to ESD tree"));
+    esd->SetFMDData(fESDObj);
+  }
+
+  if (!fDiagnostics || !esd) return;
+  static bool first = true;
+  // This is most likely NOT the event number you'd like to use. It
+  // has nothing to do with the 'real' event number. 
+  // - That's OK.  We just use it for the name of the directory -
+  // nothing else.  Christian
+  Int_t evno = esd->GetEventNumberInFile(); 
+  AliFMDDebug(1, ("Writing diagnostics histograms to FMD.Diag.root/%03d",evno));
+  TFile f("FMD.Diag.root", (first ? "RECREATE" : "UPDATE"));
+  first = false;
+  f.cd(); 
+  TDirectory* d = f.mkdir(Form("%03d", evno), 
+                         Form("Diagnostics histograms for event # %d", evno));
+  d->cd();
+  if (fDiagStep1) fDiagStep1->Write();
+  if (fDiagStep2) fDiagStep2->Write();
+  if (fDiagStep3) fDiagStep3->Write();
+  if (fDiagStep4) fDiagStep4->Write();
+  if (fDiagAll)   fDiagAll->Write();
+  d->Write();
+  f.Write();
+  f.Close();
 
+  if (fDiagStep1) fDiagStep1->Reset();
+  if (fDiagStep2) fDiagStep2->Reset();
+  if (fDiagStep3) fDiagStep3->Reset();
+  if (fDiagStep4) fDiagStep4->Reset();
+  if (fDiagAll)   fDiagAll->Reset();
+}
+
+//____________________________________________________________________
+void
+AliFMDReconstructor::FillESD(AliRawReader*, TTree* clusterTree, 
+                            AliESDEvent* esd) const
+{
+  TTree* dummy = 0;
+  FillESD(dummy, clusterTree, esd);
 }
 
 //____________________________________________________________________