TRD/AliTRDclusterizerV1.cxx

   1
   2 /**************************************************************************
   3  * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
   4  *                                                                        *
   5  * Author: The ALICE Off-line Project.                                    *
   6  * Contributors are mentioned in the code where appropriate.              *
   7  *                                                                        *
   8  * Permission to use, copy, modify and distribute this software and its   *
   9  * documentation strictly for non-commercial purposes is hereby granted   *
  10  * without fee, provided that the above copyright notice appears in all   *
  11  * copies and that both the copyright notice and this permission notice   *
  12  * appear in the supporting documentation. The authors make no claims     *
  13  * about the suitability of this software for any purpose. It is          *
  14  * provided "as is" without express or implied warranty.                  *
  15  **************************************************************************/
  16
  17 /* $Id$ */
  18
  19 ///////////////////////////////////////////////////////////////////////////////
  20 //                                                                           //
  21 // TRD cluster finder                                                        //
  22 //                                                                           //
  23 ///////////////////////////////////////////////////////////////////////////////
  24
  25 #include <TF1.h>
  26 #include <TTree.h>
  27 #include <TH1.h>
  28 #include <TFile.h>
  29
  30 #include "AliRun.h"
  31 #include "AliRunLoader.h"
  32 #include "AliLoader.h"
  33 #include "AliRawReader.h"
  34 #include "AliLog.h"
  35
  36 #include "AliTRDclusterizerV1.h"
  37 #include "AliTRDgeometry.h"
  38 #include "AliTRDdataArrayF.h"
  39 #include "AliTRDdataArrayI.h"
  40 #include "AliTRDdigitsManager.h"
  41 #include "AliTRDpadPlane.h"
  42 #include "AliTRDrawData.h"
  43 #include "AliTRDcalibDB.h"
  44 #include "AliTRDSimParam.h"
  45 #include "AliTRDRecParam.h"
  46 #include "AliTRDCommonParam.h"
  47 #include "AliTRDcluster.h"
  48
  49 ClassImp(AliTRDclusterizerV1)
  50
  51 //_____________________________________________________________________________
  52 AliTRDclusterizerV1::AliTRDclusterizerV1()
  53   :AliTRDclusterizer()
  54   ,fDigitsManager(NULL)
  55 {
  56   //
  57   // AliTRDclusterizerV1 default constructor
  58   //
  59
  60 }
  61
  62 //_____________________________________________________________________________
  63 AliTRDclusterizerV1::AliTRDclusterizerV1(const Text_t* name, const Text_t* title)
  64   :AliTRDclusterizer(name,title)
  65   ,fDigitsManager(new AliTRDdigitsManager())
  66 {
  67   //
  68   // AliTRDclusterizerV1 constructor
  69   //
  70
  71   fDigitsManager->CreateArrays();
  72
  73 }
  74
  75 //_____________________________________________________________________________
  76 AliTRDclusterizerV1::AliTRDclusterizerV1(const AliTRDclusterizerV1 &c)
  77   :AliTRDclusterizer(c)
  78   ,fDigitsManager(NULL)
  79 {
  80   //
  81   // AliTRDclusterizerV1 copy constructor
  82   //
  83
  84 }
  85
  86 //_____________________________________________________________________________
  87 AliTRDclusterizerV1::~AliTRDclusterizerV1()
  88 {
  89   //
  90   // AliTRDclusterizerV1 destructor
  91   //
  92
  93   if (fDigitsManager) {
  94     delete fDigitsManager;
  95     fDigitsManager = NULL;
  96   }
  97
  98 }
  99
 100 //_____________________________________________________________________________
 101 AliTRDclusterizerV1 &AliTRDclusterizerV1::operator=(const AliTRDclusterizerV1 &c)
 102 {
 103   //
 104   // Assignment operator
 105   //
 106
 107   if (this != &c) ((AliTRDclusterizerV1 &) c).Copy(*this);
 108   return *this;
 109
 110 }
 111
 112 //_____________________________________________________________________________
 113 void AliTRDclusterizerV1::Copy(TObject &c) const
 114 {
 115   //
 116   // Copy function
 117   //
 118
 119   ((AliTRDclusterizerV1 &) c).fDigitsManager = 0;
 120
 121   AliTRDclusterizer::Copy(c);
 122
 123 }
 124
 125 //_____________________________________________________________________________
 126 Bool_t AliTRDclusterizerV1::ReadDigits()
 127 {
 128   //
 129   // Reads the digits arrays from the input aliroot file
 130   //
 131
 132   if (!fRunLoader) {
 133     AliError("No run loader available");
 134     return kFALSE;
 135   }
 136
 137   AliLoader* loader = fRunLoader->GetLoader("TRDLoader");
 138   if (!loader->TreeD()) {
 139     loader->LoadDigits();
 140   }
 141
 142   // Read in the digit arrays
 143   return (fDigitsManager->ReadDigits(loader->TreeD()));
 144
 145 }
 146
 147 //_____________________________________________________________________________
 148 Bool_t AliTRDclusterizerV1::ReadDigits(AliRawReader* rawReader)
 149 {
 150   //
 151   // Reads the digits arrays from the ddl file
 152   //
 153
 154   AliTRDrawData raw;
 155   fDigitsManager = raw.Raw2Digits(rawReader);
 156
 157   return kTRUE;
 158
 159 }
 160
 161 //_____________________________________________________________________________
 162 Bool_t AliTRDclusterizerV1::MakeClusters()
 163 {
 164   //
 165   // Generates the cluster.
 166   //
 167
 168   Int_t row   = 0;
 169   Int_t col   = 0;
 170   Int_t time  = 0;
 171   Int_t icham = 0;
 172   Int_t iplan = 0;
 173   Int_t isect = 0;
 174   Int_t iPad  = 0;
 175
 176   AliTRDdataArrayI *digitsIn;
 177   AliTRDdataArrayI *track0;
 178   AliTRDdataArrayI *track1;
 179   AliTRDdataArrayI *track2;
 180
 181   // Get the geometry
 182   AliTRDgeometry *geo            = AliTRDgeometry::GetGeometry(fRunLoader);
 183   AliTRDcalibDB  *calibration    = AliTRDcalibDB::Instance();
 184   if (!calibration) {
 185     AliError("No AliTRDcalibDB instance available\n");
 186     return kFALSE;
 187   }
 188
 189   AliTRDSimParam *simParam       = AliTRDSimParam::Instance();
 190   if (!simParam) {
 191     AliError("No AliTRDSimParam instance available\n");
 192     return kFALSE;
 193   }
 194
 195   AliTRDRecParam *recParam       = AliTRDRecParam::Instance();
 196   if (!recParam) {
 197     AliError("No AliTRDRecParam instance available\n");
 198     return kFALSE;
 199   }
 200
 201   AliTRDCommonParam *commonParam = AliTRDCommonParam::Instance();
 202   if (!commonParam) {
 203     AliError("Could not get common parameters\n");
 204     return kFALSE;
 205   }
 206
 207   // ADC threshols
 208   Float_t ADCthreshold = simParam->GetADCthreshold();
 209   // Threshold value for the maximum
 210   Float_t maxThresh    = recParam->GetClusMaxThresh();
 211   // Threshold value for the digit signal
 212   Float_t sigThresh    = recParam->GetClusSigThresh();
 213
 214   // Iteration limit for unfolding procedure
 215   const Float_t kEpsilon = 0.01;
 216   const Int_t   kNclus   = 3;
 217   const Int_t   kNsig    = 5;
 218   const Int_t   kNtrack  = 3 * kNclus;
 219
 220   Int_t    iType         = 0;
 221   Int_t    iUnfold       = 0;
 222   Double_t ratioLeft     = 1.0;
 223   Double_t ratioRight    = 1.0;
 224
 225   Double_t padSignal[kNsig];
 226   Double_t clusterSignal[kNclus];
 227   Double_t clusterPads[kNclus];
 228   Int_t    clusterTracks[kNtrack];
 229
 230   Int_t    chamBeg    = 0;
 231   Int_t    chamEnd    = AliTRDgeometry::Ncham();
 232   Int_t    planBeg    = 0;
 233   Int_t    planEnd    = AliTRDgeometry::Nplan();
 234   Int_t    sectBeg    = 0;
 235   Int_t    sectEnd    = AliTRDgeometry::Nsect();
 236   Int_t    nTimeTotal = calibration->GetNumberOfTimeBins();
 237
 238   AliDebug(1,Form("Number of Time Bins = %d.\n",nTimeTotal));
 239
 240   // Start clustering in every chamber
 241   for (icham = chamBeg; icham < chamEnd; icham++) {
 242     for (iplan = planBeg; iplan < planEnd; iplan++) {
 243       for (isect = sectBeg; isect < sectEnd; isect++) {
 244
 245         Int_t idet    = geo->GetDetector(iplan,icham,isect);
 246
 247         Int_t nRowMax = commonParam->GetRowMax(iplan,icham,isect);
 248         Int_t nColMax = commonParam->GetColMax(iplan);
 249
 250         AliTRDpadPlane *padPlane = commonParam->GetPadPlane(iplan,icham);
 251
 252         Int_t nClusters      = 0;
 253         Int_t nClusters2pad  = 0;
 254         Int_t nClusters3pad  = 0;
 255         Int_t nClusters4pad  = 0;
 256         Int_t nClusters5pad  = 0;
 257         Int_t nClustersLarge = 0;
 258
 259         AliDebug(1,Form("Analyzing chamber %d, plane %d, sector %d.\n"
 260                        ,icham,iplan,isect));
 261
 262         // Get the digits
 263         digitsIn = fDigitsManager->GetDigits(idet);
 264         digitsIn->Expand();
 265         track0   = fDigitsManager->GetDictionary(idet,0);
 266         track0->Expand();
 267         track1   = fDigitsManager->GetDictionary(idet,1);
 268         track1->Expand();
 269         track2   = fDigitsManager->GetDictionary(idet,2);
 270         track2->Expand();
 271
 272         AliTRDdataArrayF *digitsOut = new AliTRDdataArrayF(digitsIn->GetNrow()
 273                                                           ,digitsIn->GetNcol()
 274                                                           ,digitsIn->GetNtime());
 275         Transform(digitsIn, digitsOut,idet,nRowMax,nColMax,nTimeTotal,ADCthreshold);
 276
 277         // Loop through the chamber and find the maxima
 278         for ( row = 0;  row <  nRowMax;    row++) {
 279           for ( col = 2;  col <  nColMax;    col++) {
 280             for (time = 0; time < nTimeTotal; time++) {
 281
 282               Float_t signalL = TMath::Abs(digitsOut->GetDataUnchecked(row,col  ,time));
 283               Float_t signalM = TMath::Abs(digitsOut->GetDataUnchecked(row,col-1,time));
 284               Float_t signalR = TMath::Abs(digitsOut->GetDataUnchecked(row,col-2,time));
 285
 286               // Look for the maximum
 287               if (signalM >= maxThresh) {
 288                 if ((TMath::Abs(signalL) <= signalM) &&
 289                     (TMath::Abs(signalR) <= signalM) &&
 290                     ((TMath::Abs(signalL) + TMath::Abs(signalR)) > sigThresh)) {
 291                   // Maximum found, mark the position by a negative signal
 292                   digitsOut->SetDataUnchecked(row,col-1,time,-signalM);
 293                 }
 294               }
 295
 296             }
 297           }
 298         }
 299
 300         // Now check the maxima and calculate the cluster position
 301         for ( row = 0;  row <  nRowMax  ;  row++) {
 302           for (time = 0; time < nTimeTotal; time++) {
 303             for ( col = 1;  col <  nColMax-1;  col++) {
 304
 305               // Maximum found ?
 306               if (digitsOut->GetDataUnchecked(row,col,time) < 0) {
 307
 308                 for (iPad = 0; iPad < kNclus; iPad++) {
 309                   Int_t iPadCol = col - 1 + iPad;
 310                   clusterSignal[iPad]     = TMath::Abs(digitsOut->GetDataUnchecked(row
 311                                                                                   ,iPadCol
 312                                                                                    ,time));
 313                   clusterTracks[3*iPad  ] = track0->GetDataUnchecked(row,iPadCol,time) - 1;
 314                   clusterTracks[3*iPad+1] = track1->GetDataUnchecked(row,iPadCol,time) - 1;
 315                   clusterTracks[3*iPad+2] = track2->GetDataUnchecked(row,iPadCol,time) - 1;
 316                 }
 317
 318                 // Count the number of pads in the cluster
 319                 Int_t nPadCount = 0;
 320                 Int_t ii        = 0;
 321                 while (TMath::Abs(digitsOut->GetDataUnchecked(row,col-ii  ,time)) >= sigThresh) {
 322                   nPadCount++;
 323                   ii++;
 324                   if (col-ii   <        0) break;
 325                 }
 326                 ii = 0;
 327                 while (TMath::Abs(digitsOut->GetDataUnchecked(row,col+ii+1,time)) >= sigThresh) {
 328                   nPadCount++;
 329                   ii++;
 330                   if (col+ii+1 >= nColMax) break;
 331                 }
 332
 333                 nClusters++;
 334                 switch (nPadCount) {
 335                 case 2:
 336                   iType = 0;
 337                   nClusters2pad++;
 338                   break;
 339                 case 3:
 340                   iType = 1;
 341                   nClusters3pad++;
 342                   break;
 343                 case 4:
 344                   iType = 2;
 345                   nClusters4pad++;
 346                   break;
 347                 case 5:
 348                   iType = 3;
 349                   nClusters5pad++;
 350                   break;
 351                 default:
 352                   iType = 4;
 353                   nClustersLarge++;
 354                   break;
 355                 };
 356
 357                 // Look for 5 pad cluster with minimum in the middle
 358                 Bool_t fivePadCluster = kFALSE;
 359                 if (col < (nColMax - 3)) {
 360                   if (digitsOut->GetDataUnchecked(row,col+2,time) < 0) {
 361                     fivePadCluster = kTRUE;
 362                   }
 363                   if ((fivePadCluster) && (col < (nColMax - 5))) {
 364                     if (digitsOut->GetDataUnchecked(row,col+4,time) >= sigThresh) {
 365                       fivePadCluster = kFALSE;
 366                     }
 367                   }
 368                   if ((fivePadCluster) && (col >             1)) {
 369                     if (digitsOut->GetDataUnchecked(row,col-2,time) >= sigThresh) {
 370                       fivePadCluster = kFALSE;
 371                     }
 372                   }
 373                 }
 374
 375                 // 5 pad cluster
 376                 // Modify the signal of the overlapping pad for the left part
 377                 // of the cluster which remains from a previous unfolding
 378                 if (iUnfold) {
 379                   clusterSignal[0] *= ratioLeft;
 380                   iType   = 5;
 381                   iUnfold = 0;
 382                 }
 383
 384                 // Unfold the 5 pad cluster
 385                 if (fivePadCluster) {
 386                   for (iPad = 0; iPad < kNsig; iPad++) {
 387                     padSignal[iPad] = TMath::Abs(digitsOut->GetDataUnchecked(row
 388                                                                              ,col-1+iPad
 389                                                                              ,time));
 390                   }
 391                   // Unfold the two maxima and set the signal on
 392                   // the overlapping pad to the ratio
 393                   ratioRight        = Unfold(kEpsilon,iplan,padSignal);
 394                   ratioLeft         = 1.0 - ratioRight;
 395                   clusterSignal[2] *= ratioRight;
 396                   iType   = 5;
 397                   iUnfold = 1;
 398                 }
 399
 400                 Double_t clusterCharge = clusterSignal[0]
 401                                        + clusterSignal[1]
 402                                        + clusterSignal[2];
 403
 404                 // The position of the cluster
 405                 clusterPads[0] = row + 0.5;
 406                 // Take the shift of the additional time bins into account
 407                 clusterPads[2] = time + 0.5;
 408
 409                 if (recParam->LUTOn()) {
 410                   // Calculate the position of the cluster by using the
 411                   // lookup table method
 412                   clusterPads[1] = recParam->LUTposition(iplan,clusterSignal[0]
 413                                                               ,clusterSignal[1]
 414                                                               ,clusterSignal[2]);
 415                 }
 416                 else {
 417                   // Calculate the position of the cluster by using the
 418                   // center of gravity method
 419                   for (Int_t i = 0; i < 5; i++) {
 420                     padSignal[i] = 0;
 421                   }
 422                   padSignal[2] = TMath::Abs(digitsOut->GetDataUnchecked(row,col  ,time)); // central  pad
 423                   padSignal[1] = TMath::Abs(digitsOut->GetDataUnchecked(row,col-1,time)); // left     pad
 424                   padSignal[3] = TMath::Abs(digitsOut->GetDataUnchecked(row,col+1,time)); // right    pad
 425                   if ((col >           2) &&
 426                       (TMath::Abs(digitsOut->GetDataUnchecked(row,col-2,time)) < padSignal[1])) {
 427                     padSignal[0] = TMath::Abs(digitsOut->GetDataUnchecked(row,col-2,time));
 428                   }
 429                   if ((col < nColMax - 3) &&
 430                       (TMath::Abs(digitsOut->GetDataUnchecked(row,col+2,time)) < padSignal[3])) {
 431                     padSignal[4] = TMath::Abs(digitsOut->GetDataUnchecked(row,col+2,time));
 432                   }
 433                   clusterPads[1] = GetCOG(padSignal);
 434                 }
 435
 436                 Double_t q0 = clusterSignal[0];
 437                 Double_t q1 = clusterSignal[1];
 438                 Double_t q2 = clusterSignal[2];
 439                 Double_t clusterSigmaY2 = (q1*(q0+q2)+4*q0*q2) /
 440                                           (clusterCharge*clusterCharge);
 441
 442                 //
 443                 // Calculate the position and the error
 444                 //
 445
 446                 // Correct for t0
 447                 Int_t    clusterTimeBin = TMath::Nint(time - calibration->GetT0(idet, col, row));
 448
 449                 Double_t colSize        = padPlane->GetColSize(col);
 450                 Double_t rowSize        = padPlane->GetRowSize(row);
 451
 452                 Double_t clusterPos[3];
 453                 clusterPos[0] = padPlane->GetColPos(col) - (clusterPads[1]+0.5)*colSize;
 454                 clusterPos[1] = padPlane->GetRowPos(row) - 0.5*rowSize;
 455                 clusterPos[2] = CalcXposFromTimebin(clusterPads[2],idet,col,row);
 456                 Double_t clusterSig[2];
 457                 clusterSig[0] = (clusterSigmaY2 + 1./12.) * colSize*colSize;
 458                 clusterSig[1] = rowSize * rowSize / 12.;
 459
 460
 461                 // Add the cluster to the output array
 462                 AliTRDcluster * cluster = AddCluster(clusterPos
 463                                                     ,clusterTimeBin
 464                                                     ,idet
 465                                                     ,clusterCharge
 466                                                     ,clusterTracks
 467                                                     ,clusterSig
 468                                                     ,iType
 469                                                     ,clusterPads[1]);
 470
 471                 Short_t signals[7]={ 0, 0, 0, 0, 0, 0, 0 };
 472                 for (Int_t jPad = col-3; jPad <= col+3; jPad++) {
 473                   if ((jPad < 0) || (jPad >= nColMax-1)) {
 474                     continue;
 475                   }
 476                   signals[jPad-col+3] = TMath::Nint(TMath::Abs(digitsOut->GetDataUnchecked(row,jPad,time)));
 477                 }
 478                 cluster->SetSignals(signals);
 479
 480               }
 481
 482             }
 483           }
 484         }
 485
 486         delete digitsOut;
 487
 488         // Compress the arrays
 489         track0->Compress(1,0);
 490         track1->Compress(1,0);
 491         track2->Compress(1,0);
 492
 493         // Write the cluster and reset the array
 494         WriteClusters(idet);
 495         ResetRecPoints();
 496
 497       }
 498     }
 499   }
 500
 501   return kTRUE;
 502
 503 }
 504
 505 //_____________________________________________________________________________
 506 Double_t AliTRDclusterizerV1::GetCOG(Double_t signal[5])
 507 {
 508   //
 509   // Get COG position
 510   // Used for clusters with more than 3 pads - where LUT not applicable
 511   //
 512
 513   Double_t sum = signal[0]+signal[1]+signal[2]+signal[3]+signal[4];
 514   Double_t res = (0.0*(-signal[0]+signal[4])+(-signal[1]+signal[3]))/sum;
 515
 516   return res;
 517
 518 }
 519
 520 //_____________________________________________________________________________
 521 Double_t AliTRDclusterizerV1::Unfold(Double_t eps, Int_t plane, Double_t* padSignal)
 522 {
 523   //
 524   // Method to unfold neighbouring maxima.
 525   // The charge ratio on the overlapping pad is calculated
 526   // until there is no more change within the range given by eps.
 527   // The resulting ratio is then returned to the calling method.
 528   //
 529
 530   AliTRDcalibDB* calibration = AliTRDcalibDB::Instance();
 531   if (!calibration) {
 532     AliError("No AliTRDcalibDB instance available\n");
 533     return kFALSE;
 534   }
 535
 536   Int_t   irc                = 0;
 537   Int_t   itStep             = 0;      // Count iteration steps
 538
 539   Double_t ratio             = 0.5;    // Start value for ratio
 540   Double_t prevRatio         = 0;      // Store previous ratio
 541
 542   Double_t newLeftSignal[3]  = {0};    // Array to store left cluster signal
 543   Double_t newRightSignal[3] = {0};    // Array to store right cluster signal
 544   Double_t newSignal[3]      = {0};
 545
 546   // Start the iteration
 547   while ((TMath::Abs(prevRatio - ratio) > eps) && (itStep < 10)) {
 548
 549     itStep++;
 550     prevRatio = ratio;
 551
 552     // Cluster position according to charge ratio
 553     Double_t maxLeft  = (ratio*padSignal[2] - padSignal[0])
 554                       / (padSignal[0] + padSignal[1] + ratio*padSignal[2]);
 555     Double_t maxRight = (padSignal[4] - (1-ratio)*padSignal[2])
 556                       / ((1-ratio)*padSignal[2] + padSignal[3] + padSignal[4]);
 557
 558     // Set cluster charge ratio
 559     irc = calibration->PadResponse(1.0,maxLeft ,plane,newSignal);
 560     Double_t ampLeft  = padSignal[1] / newSignal[1];
 561     irc = calibration->PadResponse(1.0,maxRight,plane,newSignal);
 562     Double_t ampRight = padSignal[3] / newSignal[1];
 563
 564     // Apply pad response to parameters
 565     irc = calibration->PadResponse(ampLeft ,maxLeft ,plane,newLeftSignal );
 566     irc = calibration->PadResponse(ampRight,maxRight,plane,newRightSignal);
 567
 568     // Calculate new overlapping ratio
 569     ratio = TMath::Min((Double_t)1.0,newLeftSignal[2] /
 570                           (newLeftSignal[2] + newRightSignal[0]));
 571
 572   }
 573
 574   return ratio;
 575
 576 }
 577
 578 //_____________________________________________________________________________
 579 void AliTRDclusterizerV1::Transform(AliTRDdataArrayI* digitsIn,
 580                                     AliTRDdataArrayF* digitsOut,
 581                                     Int_t idet, Int_t nRowMax,
 582                                     Int_t nColMax, Int_t nTimeTotal,
 583                                     Float_t ADCthreshold)
 584 {
 585   //
 586   // Apply gain factor
 587   // Apply tail cancellation: Transform digitsIn to digitsOut
 588   //
 589
 590   Int_t iRow  = 0;
 591   Int_t iCol  = 0;
 592   Int_t iTime = 0;
 593
 594   AliTRDRecParam* recParam = AliTRDRecParam::Instance();
 595   if (!recParam) {
 596     AliError("No AliTRDRecParam instance available\n");
 597     return;
 598   }
 599   AliTRDcalibDB* calibration = AliTRDcalibDB::Instance();
 600   if (!calibration) {
 601     AliError("No AliTRDcalibDB instance available\n");
 602     return;
 603   }
 604
 605   Double_t *inADC  = new Double_t[nTimeTotal];  // adc data before tail cancellation
 606   Double_t *outADC = new Double_t[nTimeTotal];  // adc data after tail cancellation
 607
 608   AliDebug(1,Form("Tail cancellation (nExp = %d) for detector %d.\n"
 609                  ,recParam->GetTCnexp(),idet));
 610
 611   for (iRow  = 0; iRow  <  nRowMax;   iRow++ ) {
 612     for (iCol  = 0; iCol  <  nColMax;   iCol++ ) {
 613       for (iTime = 0; iTime < nTimeTotal; iTime++) {
 614
 615         //
 616         // Add gain
 617         //
 618         Double_t gain = calibration->GetGainFactor(idet,iCol,iRow);
 619         if (gain == 0) {
 620           AliError("Not a valid gain\n");
 621         }
 622         inADC[iTime]  = digitsIn->GetDataUnchecked(iRow,iCol,iTime);
 623         inADC[iTime] /= gain;
 624         outADC[iTime] = inADC[iTime];
 625
 626       }
 627
 628       // Apply the tail cancelation via the digital filter
 629       if (recParam->TCOn()) {
 630         DeConvExp(inADC,outADC,nTimeTotal,recParam->GetTCnexp());
 631       }
 632
 633       for (iTime = 0; iTime < nTimeTotal; iTime++) {
 634
 635         // Store the amplitude of the digit if above threshold
 636         if (outADC[iTime] > ADCthreshold) {
 637           AliDebug(2,Form("  iRow = %d, iCol = %d, iTime = %d, adc = %f\n"
 638                          ,iRow,iCol,iTime,outADC[iTime]));
 639           digitsOut->SetDataUnchecked(iRow,iCol,iTime,outADC[iTime]);
 640         }
 641
 642       }
 643
 644     }
 645   }
 646
 647   delete [] inADC;
 648   delete [] outADC;
 649
 650   return;
 651
 652 }
 653
 654 //_____________________________________________________________________________
 655 void AliTRDclusterizerV1::DeConvExp(Double_t *source, Double_t *target,
 656                                     Int_t n, Int_t nexp)
 657 {
 658   //
 659   // Tail cancellation by deconvolution for PASA v4 TRF
 660   //
 661
 662   Double_t rates[2];
 663   Double_t coefficients[2];
 664
 665   // Initialization (coefficient = alpha, rates = lambda)
 666   Double_t R1 = 1.0;
 667   Double_t R2 = 1.0;
 668   Double_t C1 = 0.5;
 669   Double_t C2 = 0.5;
 670
 671   if (nexp == 1) {   // 1 Exponentials
 672     R1 = 1.156;
 673     R2 = 0.130;
 674     C1 = 0.066;
 675     C2 = 0.000;
 676   }
 677   if (nexp == 2) {   // 2 Exponentials
 678     R1 = 1.156;
 679     R2 = 0.130;
 680     C1 = 0.114;
 681     C2 = 0.624;
 682   }
 683
 684   coefficients[0] = C1;
 685   coefficients[1] = C2;
 686
 687   Double_t Dt = 0.100;
 688
 689   rates[0] = TMath::Exp(-Dt/(R1));
 690   rates[1] = TMath::Exp(-Dt/(R2));
 691
 692   Int_t i = 0;
 693   Int_t k = 0;
 694
 695   Double_t reminder[2];
 696   Double_t correction;
 697   Double_t result;
 698
 699   // Attention: computation order is important
 700   correction = 0.0;
 701   for (k = 0; k < nexp; k++) {
 702     reminder[k] = 0.0;
 703   }
 704   for (i = 0; i < n; i++) {
 705     result    = (source[i] - correction);    // no rescaling
 706     target[i] = result;
 707
 708     for (k = 0; k < nexp; k++) {
 709       reminder[k] = rates[k] * (reminder[k] + coefficients[k] * result);
 710     }
 711     correction = 0.0;
 712     for (k = 0; k < nexp; k++) {
 713       correction += reminder[k];
 714     }
 715   }
 716
 717 }