[u/mrichter/AliRoot.git] / TRD / AliTRDclusterizerV1.cxx

/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/*
$Log$
*/

///////////////////////////////////////////////////////////////////////////////
//                                                                           //
// TRD cluster finder for the slow simulator. 
//                                                                           //
///////////////////////////////////////////////////////////////////////////////

#include <TF1.h>

#include "AliTRDclusterizerV1.h"
#include "AliTRDmatrix.h"
#include "AliTRDgeometry.h"
#include "AliTRDdigitizer.h"
#include "AliTRDrecPoint.h"
#include "AliTRDdataArray.h"

ClassImp(AliTRDclusterizerV1)

//_____________________________________________________________________________
AliTRDclusterizerV1::AliTRDclusterizerV1():AliTRDclusterizer()
{
  //
  // AliTRDclusterizerV1 default constructor
  //

  fDigitsArray = NULL;

}

//_____________________________________________________________________________
AliTRDclusterizerV1::AliTRDclusterizerV1(const Text_t* name, const Text_t* title)
                    :AliTRDclusterizer(name,title)
{
  //
  // AliTRDclusterizerV1 default constructor
  //

  fDigitsArray = NULL;

  Init();

}

//_____________________________________________________________________________
AliTRDclusterizerV1::~AliTRDclusterizerV1()
{

  if (fDigitsArray) {
    fDigitsArray->Delete();
    delete fDigitsArray;
  }

}

//_____________________________________________________________________________
void AliTRDclusterizerV1::Init()
{
  //
  // Initializes the cluster finder
  //

  // The default parameter for the clustering
  fClusMaxThresh = 5.0;
  fClusSigThresh = 2.0;
  fClusMethod    = 1;

}

//_____________________________________________________________________________
Bool_t AliTRDclusterizerV1::ReadDigits()
{
  //
  // Reads the digits arrays from the input aliroot file
  //

  if (!fInputFile) {
    printf("AliTRDclusterizerV1::ReadDigits -- ");
    printf("No input file open\n");
    return kFALSE;
  }

  // Create a new segment array for the digits 
  fDigitsArray = new AliTRDsegmentArray(kNsect*kNplan*kNcham);

  // Read in the digit arrays
  return (fDigitsArray->LoadArray("TRDdigits"));  

}

//_____________________________________________________________________________
Bool_t AliTRDclusterizerV1::MakeCluster()
{
  //
  // Generates the cluster.
  //

  Int_t row, col, time;

  // Get the pointer to the detector class and check for version 1
  AliTRD *TRD = (AliTRD*) gAlice->GetDetector("TRD");
  if (TRD->IsVersion() != 1) {
    printf("AliTRDclusterizerV1::MakeCluster -- ");
    printf("TRD must be version 1 (slow simulator).\n");
    return kFALSE; 
  }

  // Get the geometry
  AliTRDgeometry *Geo = TRD->GetGeometry();

  printf("AliTRDclusterizerV1::MakeCluster -- ");
  printf("Start creating clusters.\n");

  AliTRDdataArray *Digits;

  // Parameters
  Float_t maxThresh        = fClusMaxThresh;   // threshold value for maximum
  Float_t signalThresh     = fClusSigThresh;   // threshold value for digit signal
  Int_t   clusteringMethod = fClusMethod;      // clustering method option (for testing)

  // Iteration limit for unfolding procedure
  const Float_t epsilon = 0.01;             

  const Int_t   nClus   = 3;  
  const Int_t   nSig    = 5;

  Int_t chamBeg = 0;
  Int_t chamEnd = kNcham;
  if (TRD->GetSensChamber() >= 0) {
    chamBeg = TRD->GetSensChamber();
    chamEnd = chamEnd + 1;
  }
  Int_t planBeg = 0;
  Int_t planEnd = kNplan;
  if (TRD->GetSensPlane()   >= 0) {
    planBeg = TRD->GetSensPlane();
    planEnd = planBeg + 1;
  }
  Int_t sectBeg = 0;
  Int_t sectEnd = kNsect;
  if (TRD->GetSensSector()  >= 0) {
    sectBeg = TRD->GetSensSector();
    sectEnd = sectBeg + 1;
  }

  // *** Start clustering *** in every chamber
  for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
    for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
      for (Int_t isect = sectBeg; isect < sectEnd; isect++) {

        Int_t idet = Geo->GetDetector(iplan,icham,isect);

        Int_t nClusters = 0;
        printf("AliTRDclusterizerV1::MakeCluster -- ");
        printf("Analyzing chamber %d, plane %d, sector %d.\n"
               ,icham,iplan,isect);

        Int_t   nRowMax  = Geo->GetRowMax(iplan,icham,isect);
        Int_t   nColMax  = Geo->GetColMax(iplan);
        Int_t   nTimeMax = Geo->GetTimeMax();

        // Create a detector matrix to keep maxima
        AliTRDmatrix *digitMatrix  = new AliTRDmatrix(nRowMax,nColMax,nTimeMax
                                                     ,isect,icham,iplan);
        // Create a matrix to contain maximum flags
        AliTRDmatrix *maximaMatrix = new AliTRDmatrix(nRowMax,nColMax,nTimeMax
                                                     ,isect,icham,iplan);

        // Read in the digits
        Digits = (AliTRDdataArray *) fDigitsArray->At(idet);

        // Loop through the detector pixel
        for (time = 0; time < nTimeMax; time++) {
          for ( col = 0;  col <  nColMax;  col++) {
            for ( row = 0;  row <  nRowMax;  row++) {

              Int_t signal = Digits->GetData(row,col,time);
              Int_t index  = Digits->GetIndex(row,col,time);

              // Fill the detector matrix
              if (signal > signalThresh) {
	        // Store the signal amplitude
                digitMatrix->SetSignal(row,col,time,signal);
	        // Store the digits number
                digitMatrix->AddTrack(row,col,time,index);
              }

	    }
	  }
	}

        // Loop chamber and find maxima in digitMatrix
        for ( row = 0;  row <  nRowMax;  row++) {
          for ( col = 1;  col <  nColMax;  col++) {
            for (time = 0; time < nTimeMax; time++) {

              if (digitMatrix->GetSignal(row,col,time) 
                  < digitMatrix->GetSignal(row,col - 1,time)) {
                // really maximum?
                if (col > 1) {
                  if (digitMatrix->GetSignal(row,col - 2,time)
                      < digitMatrix->GetSignal(row,col - 1,time)) {
                    // yes, so set maximum flag
                    maximaMatrix->SetSignal(row,col - 1,time,1);
                  }
                  else maximaMatrix->SetSignal(row,col - 1,time,0);
                }
              }

            }   // time
          }     // col
        }       // row

        // now check maxima and calculate cluster position
        for ( row = 0;  row <  nRowMax;  row++) {
          for ( col = 1;  col <  nColMax;  col++) {
            for (time = 0; time < nTimeMax; time++) {

              if ((maximaMatrix->GetSignal(row,col,time) > 0)
                  && (digitMatrix->GetSignal(row,col,time) > maxThresh)) {

                // Ratio resulting from unfolding
                Float_t ratio                =  0;    
                // Signals on max and neighbouring pads
                Float_t padSignal[nSig]      = {0};   
                // Signals from cluster
                Float_t clusterSignal[nClus] = {0};
                // Cluster pad info
                Float_t clusterPads[nClus]   = {0};   
                // Cluster digit info
                Int_t   clusterDigit[nClus]  = {0};

                for (Int_t iPad = 0; iPad < nClus; iPad++) {
                  clusterSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
                  clusterDigit[iPad]  = digitMatrix->GetTrack(row,col-1+iPad,time,0);
                }

                // neighbouring maximum on right side?
                if (col < nColMax - 2) {
                  if (maximaMatrix->GetSignal(row,col + 2,time) > 0) {

                    for (Int_t iPad = 0; iPad < 5; iPad++) {
                      padSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
                    }

                    // unfold:
                    ratio = Unfold(epsilon, padSignal);

                    // set signal on overlapping pad to ratio
                    clusterSignal[2] *= ratio;

                  }
                }
                
		// Calculate the position of the cluster
                switch (clusteringMethod) {
                case 1:
                  // method 1: simply center of mass
                  clusterPads[0] = row + 0.5;
                  clusterPads[1] = col - 0.5 + (clusterSignal[2] - clusterSignal[0]) /
                                   (clusterSignal[1] + clusterSignal[2] + clusterSignal[3]);
                  clusterPads[2] = time + 0.5;

                  nClusters++;
                  break;
                case 2:
                  // method 2: integral gauss fit on 3 pads
                  TH1F *hPadCharges = new TH1F("hPadCharges", "Charges on center 3 pads"
	                                                    , 5, -1.5, 3.5);
                  for (Int_t iCol = -1; iCol <= 3; iCol++) {
                    if (clusterSignal[iCol] < 1) clusterSignal[iCol] = 1;
                    hPadCharges->Fill(iCol, clusterSignal[iCol]);
                  }
                  hPadCharges->Fit("gaus", "IQ", "SAME", -0.5, 2.5);
                  TF1     *fPadChargeFit = hPadCharges->GetFunction("gaus");
                  Double_t  colMean = fPadChargeFit->GetParameter(1);

                  clusterPads[0] = row + 0.5;
                  clusterPads[1] = col - 1.5 + colMean;
                  clusterPads[2] = time + 0.5;

                  delete hPadCharges;

                  nClusters++;
                  break;
                }

                Float_t clusterCharge =   clusterSignal[0]
                                        + clusterSignal[1]
                                        + clusterSignal[2];

                // Add the cluster to the output array 
                TRD->AddRecPoint(clusterPads,clusterDigit,idet,clusterCharge);

              }
            }  // time
          }    // col
        }      // row

        printf("AliTRDclusterizerV1::MakeCluster -- ");
        printf("Number of clusters found: %d\n",nClusters);

        delete digitMatrix;
        delete maximaMatrix;

      }          // isect
    }            // iplan
  }              // icham

  printf("AliTRDclusterizerV1::MakeCluster -- ");
  printf("Total number of points found: %d\n"
        ,TRD->RecPoints()->GetEntries());

  // Get the pointer to the cluster branch
  TTree *ClusterTree = gAlice->TreeR(); 

  // Fill the cluster-branch
  printf("AliTRDclusterizerV1::MakeCluster -- ");
  printf("Fill the cluster tree.\n");
  ClusterTree->Fill();
  printf("AliTRDclusterizerV1::MakeCluster -- ");
  printf("Done.\n");

  return kTRUE;

}

//_____________________________________________________________________________
Float_t AliTRDclusterizerV1::Unfold(Float_t eps, Float_t* padSignal)
{
  //
  // Method to unfold neighbouring maxima.
  // The charge ratio on the overlapping pad is calculated
  // until there is no more change within the range given by eps.
  // The resulting ratio is then returned to the calling method.
  //

  Int_t   itStep            = 0;      // count iteration steps

  Float_t ratio             = 0.5;    // start value for ratio
  Float_t prevRatio         = 0;      // store previous ratio

  Float_t newLeftSignal[3]  = {0};    // array to store left cluster signal
  Float_t newRightSignal[3] = {0};    // array to store right cluster signal

  // start iteration:
  while ((TMath::Abs(prevRatio - ratio) > eps) && (itStep < 10)) {

    itStep++;
    prevRatio = ratio;

    // cluster position according to charge ratio
    Float_t maxLeft  = (ratio*padSignal[2] - padSignal[0]) /
                       (padSignal[0] + padSignal[1] + ratio*padSignal[2]);
    Float_t maxRight = (padSignal[4] - (1-ratio)*padSignal[2]) /
                       ((1-ratio)*padSignal[2] + padSignal[3] + padSignal[4]);

    // set cluster charge ratio
    Float_t ampLeft  = padSignal[1];
    Float_t ampRight = padSignal[3];

    // apply pad response to parameters
    newLeftSignal[0] = ampLeft*PadResponse(-1 - maxLeft);
    newLeftSignal[1] = ampLeft*PadResponse( 0 - maxLeft);
    newLeftSignal[2] = ampLeft*PadResponse( 1 - maxLeft);

    newRightSignal[0] = ampRight*PadResponse(-1 - maxRight);
    newRightSignal[1] = ampRight*PadResponse( 0 - maxRight);
    newRightSignal[2] = ampRight*PadResponse( 1 - maxRight);

    // calculate new overlapping ratio
    ratio = newLeftSignal[2]/(newLeftSignal[2] + newRightSignal[0]);

  }

  return ratio;

}

//_____________________________________________________________________________
Float_t AliTRDclusterizerV1::PadResponse(Float_t x)
{
  //
  // The pad response for the chevron pads. 
  // We use a simple Gaussian approximation which should be good
  // enough for our purpose.
  //

  // The parameters for the response function
  const Float_t aa  =  0.8872;
  const Float_t bb  = -0.00573;
  const Float_t cc  =  0.454;
  const Float_t cc2 =  cc*cc;

  Float_t pr = aa * (bb + TMath::Exp(-x*x / (2. * cc2)));

  return (pr);

}
Commit	Line	Data
f7336fa3	1	/**************************************************************************
	2	* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
	3	* *
	4	* Author: The ALICE Off-line Project. *
	5	* Contributors are mentioned in the code where appropriate. *
	6	* *
	7	* Permission to use, copy, modify and distribute this software and its *
	8	* documentation strictly for non-commercial purposes is hereby granted *
	9	* without fee, provided that the above copyright notice appears in all *
	10	* copies and that both the copyright notice and this permission notice *
	11	* appear in the supporting documentation. The authors make no claims *
	12	* about the suitability of this software for any purpose. It is *
	13	* provided "as is" without express or implied warranty. *
	14	**************************************************************************/
	15
	16	/*
	17	$Log$
	18	*/
	19
	20	///////////////////////////////////////////////////////////////////////////////
	21	// //
	22	// TRD cluster finder for the slow simulator.
	23	// //
	24	///////////////////////////////////////////////////////////////////////////////
	25
	26	#include <TF1.h>
	27
	28	#include "AliTRDclusterizerV1.h"
	29	#include "AliTRDmatrix.h"
	30	#include "AliTRDgeometry.h"
	31	#include "AliTRDdigitizer.h"
	32	#include "AliTRDrecPoint.h"
	33	#include "AliTRDdataArray.h"
	34
	35	ClassImp(AliTRDclusterizerV1)
	36
	37	//_____________________________________________________________________________
	38	AliTRDclusterizerV1::AliTRDclusterizerV1():AliTRDclusterizer()
	39	{
	40	//
	41	// AliTRDclusterizerV1 default constructor
	42	//
	43
	44	fDigitsArray = NULL;
	45
	46	}
	47
	48	//_____________________________________________________________________________
	49	AliTRDclusterizerV1::AliTRDclusterizerV1(const Text_t* name, const Text_t* title)
	50	:AliTRDclusterizer(name,title)
	51	{
	52	//
	53	// AliTRDclusterizerV1 default constructor
	54	//
	55
	56	fDigitsArray = NULL;
	57
	58	Init();
	59
	60	}
	61
	62	//_____________________________________________________________________________
	63	AliTRDclusterizerV1::~AliTRDclusterizerV1()
	64	{
65
66	if (fDigitsArray) {
67	fDigitsArray->Delete();
68	delete fDigitsArray;
69	}
70
71	}
72
73	//_____________________________________________________________________________
74	void AliTRDclusterizerV1::Init()
75	{
76	//
77	// Initializes the cluster finder
78	//
79
80	// The default parameter for the clustering
81	fClusMaxThresh = 5.0;
82	fClusSigThresh = 2.0;
83	fClusMethod = 1;
84
85	}
86
87	//_____________________________________________________________________________
88	Bool_t AliTRDclusterizerV1::ReadDigits()
89	{
90	//
91	// Reads the digits arrays from the input aliroot file
92	//
93
94	if (!fInputFile) {
95	printf("AliTRDclusterizerV1::ReadDigits -- ");
96	printf("No input file open\n");
97	return kFALSE;
98	}
99
100	// Create a new segment array for the digits
101	fDigitsArray = new AliTRDsegmentArray(kNsectkNplankNcham);
102
103	// Read in the digit arrays
104	return (fDigitsArray->LoadArray("TRDdigits"));
105
106	}
107
108	//_____________________________________________________________________________
109	Bool_t AliTRDclusterizerV1::MakeCluster()
110	{
111	//
112	// Generates the cluster.
113	//
114
115	Int_t row, col, time;
116
117	// Get the pointer to the detector class and check for version 1
118	AliTRD TRD = (AliTRD) gAlice->GetDetector("TRD");
119	if (TRD->IsVersion() != 1) {
120	printf("AliTRDclusterizerV1::MakeCluster -- ");
121	printf("TRD must be version 1 (slow simulator).\n");
122	return kFALSE;
123	}
124
125	// Get the geometry
126	AliTRDgeometry *Geo = TRD->GetGeometry();
127
128	printf("AliTRDclusterizerV1::MakeCluster -- ");
129	printf("Start creating clusters.\n");
130
131	AliTRDdataArray *Digits;
132
133	// Parameters
134	Float_t maxThresh = fClusMaxThresh; // threshold value for maximum
135	Float_t signalThresh = fClusSigThresh; // threshold value for digit signal
136	Int_t clusteringMethod = fClusMethod; // clustering method option (for testing)
137
138	// Iteration limit for unfolding procedure
139	const Float_t epsilon = 0.01;
140
141	const Int_t nClus = 3;
142	const Int_t nSig = 5;
143
144	Int_t chamBeg = 0;
145	Int_t chamEnd = kNcham;
146	if (TRD->GetSensChamber() >= 0) {
147	chamBeg = TRD->GetSensChamber();
148	chamEnd = chamEnd + 1;
149	}
150	Int_t planBeg = 0;
151	Int_t planEnd = kNplan;
152	if (TRD->GetSensPlane() >= 0) {
153	planBeg = TRD->GetSensPlane();
154	planEnd = planBeg + 1;
155	}
156	Int_t sectBeg = 0;
157	Int_t sectEnd = kNsect;
158	if (TRD->GetSensSector() >= 0) {
159	sectBeg = TRD->GetSensSector();
160	sectEnd = sectBeg + 1;
161	}
162
163	// * Start clustering * in every chamber
164	for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
165	for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
166	for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
167
168	Int_t idet = Geo->GetDetector(iplan,icham,isect);
169
170	Int_t nClusters = 0;
171	printf("AliTRDclusterizerV1::MakeCluster -- ");
172	printf("Analyzing chamber %d, plane %d, sector %d.\n"
173	,icham,iplan,isect);
174
175	Int_t nRowMax = Geo->GetRowMax(iplan,icham,isect);
176	Int_t nColMax = Geo->GetColMax(iplan);
177	Int_t nTimeMax = Geo->GetTimeMax();
178
179	// Create a detector matrix to keep maxima
180	AliTRDmatrix *digitMatrix = new AliTRDmatrix(nRowMax,nColMax,nTimeMax
181	,isect,icham,iplan);
182	// Create a matrix to contain maximum flags
183	AliTRDmatrix *maximaMatrix = new AliTRDmatrix(nRowMax,nColMax,nTimeMax
184	,isect,icham,iplan);
185
186	// Read in the digits
187	Digits = (AliTRDdataArray *) fDigitsArray->At(idet);
188
189	// Loop through the detector pixel
190	for (time = 0; time < nTimeMax; time++) {
191	for ( col = 0; col < nColMax; col++) {
192	for ( row = 0; row < nRowMax; row++) {
193
194	Int_t signal = Digits->GetData(row,col,time);
195	Int_t index = Digits->GetIndex(row,col,time);
196
197	// Fill the detector matrix
198	if (signal > signalThresh) {
199	// Store the signal amplitude
200	digitMatrix->SetSignal(row,col,time,signal);
201	// Store the digits number
202	digitMatrix->AddTrack(row,col,time,index);
203	}
204
205	}
206	}
207	}
208
209	// Loop chamber and find maxima in digitMatrix
210	for ( row = 0; row < nRowMax; row++) {
211	for ( col = 1; col < nColMax; col++) {
212	for (time = 0; time < nTimeMax; time++) {
213
214	if (digitMatrix->GetSignal(row,col,time)
215	< digitMatrix->GetSignal(row,col - 1,time)) {
216	// really maximum?
217	if (col > 1) {
218	if (digitMatrix->GetSignal(row,col - 2,time)
219	< digitMatrix->GetSignal(row,col - 1,time)) {
220	// yes, so set maximum flag
221	maximaMatrix->SetSignal(row,col - 1,time,1);
222	}
223	else maximaMatrix->SetSignal(row,col - 1,time,0);
224	}
225	}
226
227	} // time
228	} // col
229	} // row
230
231	// now check maxima and calculate cluster position
232	for ( row = 0; row < nRowMax; row++) {
233	for ( col = 1; col < nColMax; col++) {
234	for (time = 0; time < nTimeMax; time++) {
235
236	if ((maximaMatrix->GetSignal(row,col,time) > 0)
237	&& (digitMatrix->GetSignal(row,col,time) > maxThresh)) {
238
239	// Ratio resulting from unfolding
240	Float_t ratio = 0;
241	// Signals on max and neighbouring pads
242	Float_t padSignal[nSig] = {0};
243	// Signals from cluster
244	Float_t clusterSignal[nClus] = {0};
245	// Cluster pad info
246	Float_t clusterPads[nClus] = {0};
247	// Cluster digit info
248	Int_t clusterDigit[nClus] = {0};
249
250	for (Int_t iPad = 0; iPad < nClus; iPad++) {
251	clusterSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
252	clusterDigit[iPad] = digitMatrix->GetTrack(row,col-1+iPad,time,0);
253	}
254
255	// neighbouring maximum on right side?
256	if (col < nColMax - 2) {
257	if (maximaMatrix->GetSignal(row,col + 2,time) > 0) {
258
259	for (Int_t iPad = 0; iPad < 5; iPad++) {
260	padSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
261	}
262
263	// unfold:
264	ratio = Unfold(epsilon, padSignal);
265
266	// set signal on overlapping pad to ratio
267	clusterSignal[2] *= ratio;
268
269	}
270	}
271
272	// Calculate the position of the cluster
273	switch (clusteringMethod) {
274	case 1:
275	// method 1: simply center of mass
276	clusterPads[0] = row + 0.5;
277	clusterPads[1] = col - 0.5 + (clusterSignal[2] - clusterSignal[0]) /
278	(clusterSignal[1] + clusterSignal[2] + clusterSignal[3]);
279	clusterPads[2] = time + 0.5;
280
281	nClusters++;
282	break;
283	case 2:
284	// method 2: integral gauss fit on 3 pads
285	TH1F *hPadCharges = new TH1F("hPadCharges", "Charges on center 3 pads"
286	, 5, -1.5, 3.5);
287	for (Int_t iCol = -1; iCol <= 3; iCol++) {
288	if (clusterSignal[iCol] < 1) clusterSignal[iCol] = 1;
289	hPadCharges->Fill(iCol, clusterSignal[iCol]);
290	}
291	hPadCharges->Fit("gaus", "IQ", "SAME", -0.5, 2.5);
292	TF1 *fPadChargeFit = hPadCharges->GetFunction("gaus");
293	Double_t colMean = fPadChargeFit->GetParameter(1);
294
295	clusterPads[0] = row + 0.5;
296	clusterPads[1] = col - 1.5 + colMean;
297	clusterPads[2] = time + 0.5;
298
299	delete hPadCharges;
300
301	nClusters++;
302	break;
303	}
304
305	Float_t clusterCharge = clusterSignal[0]
306	+ clusterSignal[1]
307	+ clusterSignal[2];
308
309	// Add the cluster to the output array
310	TRD->AddRecPoint(clusterPads,clusterDigit,idet,clusterCharge);
311
312	}
313	} // time
314	} // col
315	} // row
316
317	printf("AliTRDclusterizerV1::MakeCluster -- ");
318	printf("Number of clusters found: %d\n",nClusters);
319
320	delete digitMatrix;
321	delete maximaMatrix;
322
323	} // isect
324	} // iplan
325	} // icham
326
327	printf("AliTRDclusterizerV1::MakeCluster -- ");
328	printf("Total number of points found: %d\n"
329	,TRD->RecPoints()->GetEntries());
330
331	// Get the pointer to the cluster branch
332	TTree *ClusterTree = gAlice->TreeR();
333
334	// Fill the cluster-branch
335	printf("AliTRDclusterizerV1::MakeCluster -- ");
336	printf("Fill the cluster tree.\n");
337	ClusterTree->Fill();
338	printf("AliTRDclusterizerV1::MakeCluster -- ");
339	printf("Done.\n");
340
341	return kTRUE;
342
343	}
344
345	//_____________________________________________________________________________
346	Float_t AliTRDclusterizerV1::Unfold(Float_t eps, Float_t* padSignal)
347	{
348	//
349	// Method to unfold neighbouring maxima.
350	// The charge ratio on the overlapping pad is calculated
351	// until there is no more change within the range given by eps.
352	// The resulting ratio is then returned to the calling method.
353	//
354
355	Int_t itStep = 0; // count iteration steps
356
357	Float_t ratio = 0.5; // start value for ratio
358	Float_t prevRatio = 0; // store previous ratio
359
360	Float_t newLeftSignal[3] = {0}; // array to store left cluster signal
361	Float_t newRightSignal[3] = {0}; // array to store right cluster signal
362
363	// start iteration:
364	while ((TMath::Abs(prevRatio - ratio) > eps) && (itStep < 10)) {
365
366	itStep++;
367	prevRatio = ratio;
368
369	// cluster position according to charge ratio
370	Float_t maxLeft = (ratio*padSignal[2] - padSignal[0]) /
371	(padSignal[0] + padSignal[1] + ratio*padSignal[2]);
372	Float_t maxRight = (padSignal[4] - (1-ratio)*padSignal[2]) /
373	((1-ratio)*padSignal[2] + padSignal[3] + padSignal[4]);
374
375	// set cluster charge ratio
376	Float_t ampLeft = padSignal[1];
377	Float_t ampRight = padSignal[3];
378
379	// apply pad response to parameters
380	newLeftSignal[0] = ampLeft*PadResponse(-1 - maxLeft);
381	newLeftSignal[1] = ampLeft*PadResponse( 0 - maxLeft);
382	newLeftSignal[2] = ampLeft*PadResponse( 1 - maxLeft);
383
384	newRightSignal[0] = ampRight*PadResponse(-1 - maxRight);
385	newRightSignal[1] = ampRight*PadResponse( 0 - maxRight);
386	newRightSignal[2] = ampRight*PadResponse( 1 - maxRight);
387
388	// calculate new overlapping ratio
389	ratio = newLeftSignal[2]/(newLeftSignal[2] + newRightSignal[0]);
390
391	}
392
393	return ratio;
394
395	}
396
397	//_____________________________________________________________________________
398	Float_t AliTRDclusterizerV1::PadResponse(Float_t x)
399	{
400	//
401	// The pad response for the chevron pads.
402	// We use a simple Gaussian approximation which should be good
403	// enough for our purpose.
404	//
405
406	// The parameters for the response function
407	const Float_t aa = 0.8872;
408	const Float_t bb = -0.00573;
409	const Float_t cc = 0.454;
410	const Float_t cc2 = cc*cc;
411
412	Float_t pr = aa * (bb + TMath::Exp(-xx / (2. cc2)));
413
414	return (pr);
415
416	}