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4c039060 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$Log$
5c7f4665 18Revision 1.11 1999/11/01 20:41:51 fca
19Added protections against using the wrong version of FRAME
20
ab76897d 21Revision 1.10 1999/09/29 09:24:35 fca
22Introduction of the Copyright and cvs Log
23
4c039060 24*/
25
fe4da5cc 26///////////////////////////////////////////////////////////////////////////////
27// //
5c7f4665 28// Transition Radiation Detector version 2 -- slow simulator //
fe4da5cc 29// //
30//Begin_Html
31/*
5c7f4665 32<img src="picts/AliTRDfullClass.gif">
fe4da5cc 33*/
34//End_Html
35// //
36// //
37///////////////////////////////////////////////////////////////////////////////
38
39#include <TMath.h>
fe4da5cc 40#include <TVector.h>
5c7f4665 41#include <TRandom.h>
fe4da5cc 42
fe4da5cc 43#include "AliTRDv1.h"
5c7f4665 44#include "AliTRDmatrix.h"
fe4da5cc 45#include "AliRun.h"
fe4da5cc 46#include "AliMC.h"
d3f347ff 47#include "AliConst.h"
5c7f4665 48
fe4da5cc 49ClassImp(AliTRDv1)
50
51//_____________________________________________________________________________
52AliTRDv1::AliTRDv1(const char *name, const char *title)
53 :AliTRD(name, title)
54{
55 //
5c7f4665 56 // Standard constructor for Transition Radiation Detector version 2
fe4da5cc 57 //
82bbf98a 58
5c7f4665 59 fIdSens = 0;
60
61 fIdChamber1 = 0;
62 fIdChamber2 = 0;
63 fIdChamber3 = 0;
64
65 fSensSelect = 0;
66 fSensPlane = 0;
67 fSensChamber = 0;
68 fSensSector = 0;
82bbf98a 69
5c7f4665 70 fGasGain = 0;
71 fNoise = 0;
72 fChipGain = 0;
73 fADCoutRange = 0;
74 fADCinRange = 0;
75 fADCthreshold = 0;
76
77 fDiffusionT = 0;
78 fDiffusionL = 0;
79
80 fClusMaxThresh = 0;
81 fClusSigThresh = 0;
82 fClusMethod = 0;
83
84 fDeltaE = NULL;
85
86 SetBufferSize(128000);
87
88}
89
90//_____________________________________________________________________________
91AliTRDv1::~AliTRDv1()
92{
82bbf98a 93
5c7f4665 94 if (fDeltaE) delete fDeltaE;
82bbf98a 95
fe4da5cc 96}
97
98//_____________________________________________________________________________
99void AliTRDv1::CreateGeometry()
100{
101 //
5c7f4665 102 // Create the GEANT geometry for the Transition Radiation Detector - Version 2
103 // This version covers the full azimuth.
d3f347ff 104 //
105
82bbf98a 106 // Check that FRAME is there otherwise we have no place where to put the TRD
107 AliModule* FRAME = gAlice->GetModule("FRAME");
108 if (!FRAME) return;
d3f347ff 109
82bbf98a 110 // Define the chambers
111 AliTRD::CreateGeometry();
d3f347ff 112
fe4da5cc 113}
114
115//_____________________________________________________________________________
116void AliTRDv1::CreateMaterials()
117{
118 //
5c7f4665 119 // Create materials for the Transition Radiation Detector version 2
fe4da5cc 120 //
82bbf98a 121
d3f347ff 122 AliTRD::CreateMaterials();
82bbf98a 123
fe4da5cc 124}
125
126//_____________________________________________________________________________
5c7f4665 127void AliTRDv1::Diffusion(Float_t driftlength, Float_t *xyz)
fe4da5cc 128{
129 //
5c7f4665 130 // Applies the diffusion smearing to the position of a single electron
fe4da5cc 131 //
82bbf98a 132
5c7f4665 133 if ((driftlength > 0) &&
134 (driftlength < kDrThick)) {
135 Float_t driftSqrt = TMath::Sqrt(driftlength);
136 Float_t sigmaT = driftSqrt * fDiffusionT;
137 Float_t sigmaL = driftSqrt * fDiffusionL;
138 xyz[0] = gRandom->Gaus(xyz[0], sigmaL);
139 xyz[1] = gRandom->Gaus(xyz[1], sigmaT);
140 xyz[2] = gRandom->Gaus(xyz[2], sigmaT);
141 }
142 else {
143 xyz[0] = 0.0;
144 xyz[1] = 0.0;
145 xyz[2] = 0.0;
146 }
ab76897d 147
5c7f4665 148}
82bbf98a 149
5c7f4665 150//_____________________________________________________________________________
151void AliTRDv1::Hits2Digits()
152{
153 //
154 // Creates TRD digits from hits. This procedure includes the following:
155 // - Diffusion
156 // - Gas gain including fluctuations
157 // - Pad-response (simple Gaussian approximation)
158 // - Electronics noise
159 // - Electronics gain
160 // - Digitization
161 // - ADC threshold
162 // The corresponding parameter can be adjusted via the various Set-functions.
163 // If these parameters are not explicitly set, default values are used (see
164 // Init-function).
165 // To produce digits from a root-file with TRD-hits use the
166 // slowDigitsCreate.C macro.
ab76897d 167 //
5c7f4665 168
169 printf("AliTRDv1::Hits2Digits -- Start creating digits\n");
170
171 ///////////////////////////////////////////////////////////////
172 // Parameter
173 ///////////////////////////////////////////////////////////////
174
175 // Converts number of electrons to fC
176 const Float_t el2fC = 1.602E-19 * 1.0E15;
177
178 ///////////////////////////////////////////////////////////////
179
180 Int_t nBytes = 0;
181
182 AliTRDhit *TRDhit;
183
184 // Get the pointer to the hit tree
185 TTree *HitTree = gAlice->TreeH();
186 // Get the pointer to the digits tree
187 TTree *DigitsTree = gAlice->TreeD();
188
189 // Get the number of entries in the hit tree
190 // (Number of primary particles creating a hit somewhere)
191 Int_t nTrack = (Int_t) HitTree->GetEntries();
192
193 Int_t chamBeg = 0;
194 Int_t chamEnd = kNcham;
195 if (fSensChamber) chamEnd = chamBeg = fSensChamber;
196 Int_t planBeg = 0;
197 Int_t planEnd = kNplan;
198 if (fSensPlane) planEnd = planBeg = fSensPlane;
199 Int_t sectBeg = 0;
200 Int_t sectEnd = kNsect;
201 if (fSensSector) sectEnd = sectBeg = fSensSector;
202
203 // Loop through all the chambers
204 for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
205 for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
206 for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
207
208 Int_t nDigits = 0;
209
210 printf("AliTRDv1::Hits2Digits -- Digitizing chamber %d, plane %d, sector %d\n"
211 ,icham+1,iplan+1,isect+1);
212
213 // Create a detector matrix to keep the signal and track numbers
214 AliTRDmatrix *matrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
215 ,fColMax[iplan]
216 ,fTimeMax
217 ,isect+1,icham+1,iplan+1);
218
219 // Loop through all entries in the tree
220 for (Int_t iTrack = 0; iTrack < nTrack; iTrack++) {
221
222 gAlice->ResetHits();
223 nBytes += HitTree->GetEvent(iTrack);
224
225 // Get the number of hits in the TRD created by this particle
226 Int_t nHit = fHits->GetEntriesFast();
227
228 // Loop through the TRD hits
229 for (Int_t iHit = 0; iHit < nHit; iHit++) {
230
231 if (!(TRDhit = (AliTRDhit *) fHits->UncheckedAt(iHit)))
232 continue;
233
234 Float_t x = TRDhit->fX;
235 Float_t y = TRDhit->fY;
236 Float_t z = TRDhit->fZ;
237 Float_t q = TRDhit->fQ;
238 Int_t track = TRDhit->fTrack;
239 Int_t plane = TRDhit->fPlane;
240 Int_t sector = TRDhit->fSector;
241 Int_t chamber = TRDhit->fChamber;
242
243 if ((sector != isect+1) ||
244 (plane != iplan+1) ||
245 (chamber != icham+1))
246 continue;
247
248 // Rotate the sectors on top of each other
249 Float_t phi = 2.0 * kPI / (Float_t) kNsect
250 * ((Float_t) sector - 0.5);
251 Float_t xRot = -x * TMath::Cos(phi) + y * TMath::Sin(phi);
252 Float_t yRot = x * TMath::Sin(phi) + y * TMath::Cos(phi);
253 Float_t zRot = z;
254
255 // The hit position in pad coordinates (center pad)
256 // The pad row (z-direction)
257 Int_t rowH = (Int_t) ((zRot - fRow0[iplan][icham][isect]) / fRowPadSize);
258 // The pad column (rphi-direction)
259 Int_t colH = (Int_t) ((yRot - fCol0[iplan] ) / fColPadSize);
260 // The time bucket
261 Int_t timeH = (Int_t) ((xRot - fTime0[iplan] ) / fTimeBinSize);
262
263 // Array to sum up the signal in a box surrounding the
264 // hit postition
265 const Int_t timeBox = 5;
266 const Int_t colBox = 7;
267 const Int_t rowBox = 5;
268 Float_t signalSum[rowBox][colBox][timeBox];
269 for (Int_t iRow = 0; iRow < rowBox; iRow++ ) {
270 for (Int_t iCol = 0; iCol < colBox; iCol++ ) {
271 for (Int_t iTime = 0; iTime < timeBox; iTime++) {
272 signalSum[iRow][iCol][iTime] = 0;
273 }
274 }
275 }
276
277 // Loop over all electrons of this hit
278 Int_t nEl = (Int_t) q;
279 for (Int_t iEl = 0; iEl < nEl; iEl++) {
280
281 // Apply the diffusion smearing
282 Float_t driftlength = xRot - fTime0[iplan];
283 Float_t xyz[3];
284 xyz[0] = xRot;
285 xyz[1] = yRot;
286 xyz[2] = zRot;
287 Diffusion(driftlength,xyz);
288
289 // At this point absorption effects that depend on the
290 // driftlength could be taken into account.
291
292 // The electron position and the distance to the hit position
293 // in pad units
294 // The pad row (z-direction)
295 Int_t rowE = (Int_t) ((xyz[2] - fRow0[iplan][icham][isect]) / fRowPadSize);
296 Int_t rowD = rowH - rowE;
297 // The pad column (rphi-direction)
298 Int_t colE = (Int_t) ((xyz[1] - fCol0[iplan] ) / fColPadSize);
299 Int_t colD = colH - colE;
300 // The time bucket
301 Int_t timeE = (Int_t) ((xyz[0] - fTime0[iplan] ) / fTimeBinSize);
302 Int_t timeD = timeH - timeE;
303
304 // Apply the gas gain including fluctuations
305 Int_t signal = (Int_t) (-fGasGain * TMath::Log(gRandom->Rndm()));
306
307 // The distance of the electron to the center of the pad
308 // in units of pad width
309 Float_t dist = (xyz[1] - fCol0[iplan] - (colE + 0.5) * fColPadSize)
310 / fColPadSize;
311
312 // Sum up the signal in the different pixels
313 // and apply the pad response
314 Int_t rowIdx = rowD + (Int_t) ( rowBox / 2);
315 Int_t colIdx = colD + (Int_t) ( colBox / 2);
316 Int_t timeIdx = timeD + (Int_t) (timeBox / 2);
317 signalSum[rowIdx][colIdx-1][timeIdx] += PadResponse(dist-1.) * signal;
318 signalSum[rowIdx][colIdx ][timeIdx] += PadResponse(dist ) * signal;
319 signalSum[rowIdx][colIdx+1][timeIdx] += PadResponse(dist+1.) * signal;
320
321 }
322
323 // Add the padcluster to the detector matrix
324 for (Int_t iRow = 0; iRow < rowBox; iRow++ ) {
325 for (Int_t iCol = 0; iCol < colBox; iCol++ ) {
326 for (Int_t iTime = 0; iTime < timeBox; iTime++) {
327
328 Int_t rowB = rowH + iRow - (Int_t) ( rowBox / 2);
329 Int_t colB = colH + iCol - (Int_t) ( colBox / 2);
330 Int_t timeB = timeH + iTime - (Int_t) (timeBox / 2);
331
332 Float_t signalB = signalSum[iRow][iCol][iTime];
333 if (signalB > 0.0) {
334 matrix->AddSignal(rowB,colB,timeB,signalB);
335 if (!(matrix->AddTrack(rowB,colB,timeB,track)))
336 printf(" More than three tracks in a pixel!\n");
337 }
338
339 }
340 }
341 }
342
343 }
344
345 }
346
347 // Create the hits for this chamber
348 for (Int_t iRow = 0; iRow < fRowMax[iplan][icham][isect]; iRow++ ) {
349 for (Int_t iCol = 0; iCol < fColMax[iplan] ; iCol++ ) {
350 for (Int_t iTime = 0; iTime < fTimeMax ; iTime++) {
351
352 Float_t signalAmp = matrix->GetSignal(iRow,iCol,iTime);
353
354 // Add the noise
355 signalAmp = TMath::Max(gRandom->Gaus(signalAmp,fNoise),(Float_t) 0.0);
356 // Convert to fC
357 signalAmp *= el2fC;
358 // Convert to mV
359 signalAmp *= fChipGain;
360 // Convert to ADC counts
361 Int_t adc = (Int_t) (signalAmp * (fADCoutRange / fADCinRange));
362
363 // Apply threshold on ADC value
364 if (adc > fADCthreshold) {
365
366 Int_t trackSave[3];
367 for (Int_t ii = 0; ii < 3; ii++) {
368 trackSave[ii] = matrix->GetTrack(iRow,iCol,iTime,ii);
369 }
370
371 Int_t digits[7];
372 digits[0] = matrix->GetSector();
373 digits[1] = matrix->GetChamber();
374 digits[2] = matrix->GetPlane();
375 digits[3] = iRow;
376 digits[4] = iCol;
377 digits[5] = iTime;
378 digits[6] = adc;
379
380 // Add this digit to the TClonesArray
381 AddDigit(trackSave,digits);
382 nDigits++;
383
384 }
385
386 }
387 }
388 }
389
390 printf("AliTRDv1::Hits2Digits -- Number of digits found: %d\n",nDigits);
391
392 // Clean up
393 delete matrix;
394
395 }
ab76897d 396 }
5c7f4665 397 }
ab76897d 398
5c7f4665 399 // Fill the digits-tree
400 printf("AliTRDv1::Hits2Digits -- Fill the digits tree\n");
401 DigitsTree->Fill();
402
403}
404
405//_____________________________________________________________________________
406void AliTRDv1::Digits2Clusters()
407{
408
409 //
410 // Method to convert AliTRDdigits created by AliTRDv1::Hits2Digits()
411 // into AliTRDclusters
412 // To produce cluster from a root-file with TRD-digits use the
413 // slowClusterCreate.C macro.
414 //
415
416 printf("AliTRDv1::Digits2Clusters -- Start creating clusters\n");
417
418 AliTRDdigit *TRDdigit;
419 TClonesArray *TRDDigits;
420
421 // Parameters
422 Float_t maxThresh = fClusMaxThresh; // threshold value for maximum
423 Float_t signalThresh = fClusSigThresh; // threshold value for digit signal
424 Int_t clusteringMethod = fClusMethod; // clustering method option (for testing)
425
426 const Float_t epsilon = 0.01; // iteration limit for unfolding procedure
427
428 // Get the pointer to the digits tree
429 TTree *DigitTree = gAlice->TreeD();
430 // Get the pointer to the cluster tree
431 TTree *ClusterTree = gAlice->TreeD();
432
433 // Get the pointer to the digits container
434 TRDDigits = Digits();
435
436 Int_t chamBeg = 0;
437 Int_t chamEnd = kNcham;
438 if (fSensChamber) chamEnd = chamBeg = fSensChamber;
439 Int_t planBeg = 0;
440 Int_t planEnd = kNplan;
441 if (fSensPlane) planEnd = planBeg = fSensPlane;
442 Int_t sectBeg = 0;
443 Int_t sectEnd = kNsect;
444 if (fSensSector) sectEnd = sectBeg = fSensSector;
445
446 // Import the digit tree
447 gAlice->ResetDigits();
448 Int_t nbytes;
449 nbytes += DigitTree->GetEvent(1);
450
451 // Get the number of digits in the detector
452 Int_t nTRDDigits = TRDDigits->GetEntriesFast();
453
454 // *** Start clustering *** in every chamber
455 for (Int_t icham = chamBeg; icham < chamEnd; icham++) {
456 for (Int_t iplan = planBeg; iplan < planEnd; iplan++) {
457 for (Int_t isect = sectBeg; isect < sectEnd; isect++) {
458
459 Int_t nClusters = 0;
460 printf("AliTRDv1::Digits2Clusters -- Finding clusters in chamber %d, plane %d, sector %d\n"
461 ,icham+1,iplan+1,isect+1);
462
463 // Create a detector matrix to keep maxima
464 AliTRDmatrix *digitMatrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
465 ,fColMax[iplan]
466 ,fTimeMax,isect+1
467 ,icham+1,iplan+1);
468 // Create a matrix to contain maximum flags
469 AliTRDmatrix *maximaMatrix = new AliTRDmatrix(fRowMax[iplan][icham][isect]
470 ,fColMax[iplan]
471 ,fTimeMax
472 ,isect+1,icham+1,iplan+1);
473
474 // Loop through all TRD digits
475 for (Int_t iTRDDigits = 0; iTRDDigits < nTRDDigits; iTRDDigits++) {
476
477 // Get the information for this digit
478 TRDdigit = (AliTRDdigit*) TRDDigits->UncheckedAt(iTRDDigits);
479 Int_t signal = TRDdigit->fSignal;
480 Int_t sector = TRDdigit->fSector;
481 Int_t chamber = TRDdigit->fChamber;
482 Int_t plane = TRDdigit->fPlane;
483 Int_t row = TRDdigit->fRow;
484 Int_t col = TRDdigit->fCol;
485 Int_t time = TRDdigit->fTime;
486
487 Int_t track[3];
488 for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
489 track[iTrack] = TRDdigit->AliDigit::fTracks[iTrack];
490 }
491
492 if ((sector != isect+1) ||
493 (plane != iplan+1) ||
494 (chamber != icham+1))
495 continue;
496
497 // Fill the detector matrix
498 if (signal > signalThresh) {
499 digitMatrix->SetSignal(row,col,time,signal);
500 for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
501 if (track[iTrack] > 0) {
502 digitMatrix->AddTrack(row,col,time,track[iTrack]);
503 }
504 }
505 }
506
507 }
508
509 // Loop chamber and find maxima in digitMatrix
510 for (Int_t row = 0; row < fRowMax[iplan][icham][isect]; row++) {
511 for (Int_t col = 1; col < fColMax[iplan] ; col++) {
512 for (Int_t time = 0; time < fTimeMax ; time++) {
513
514 if (digitMatrix->GetSignal(row,col,time)
515 < digitMatrix->GetSignal(row,col - 1,time)) {
516 // really maximum?
517 if (col > 1) {
518 if (digitMatrix->GetSignal(row,col - 2,time)
519 < digitMatrix->GetSignal(row,col - 1,time)) {
520 // yes, so set maximum flag
521 maximaMatrix->SetSignal(row,col - 1,time,1);
522 }
523 else maximaMatrix->SetSignal(row,col - 1,time,0);
524 }
525 }
526
527 } // time
528 } // col
529 } // row
530
531 // now check maxima and calculate cluster position
532 for (Int_t row = 0; row < fRowMax[iplan][icham][isect]; row++) {
533 for (Int_t col = 1; col < fColMax[iplan] ; col++) {
534 for (Int_t time = 0; time < fTimeMax ; time++) {
535
536 if ((maximaMatrix->GetSignal(row,col,time) > 0)
537 && (digitMatrix->GetSignal(row,col,time) > maxThresh)) {
538
539 Int_t clusters[5] = {0}; // cluster-object data
540
541 Float_t ratio = 0; // ratio resulting from unfolding
542 Float_t padSignal[5] = {0}; // signals on max and neighbouring pads
543 Float_t clusterSignal[3] = {0}; // signals from cluster
544 Float_t clusterPos[3] = {0}; // cluster in ALICE refFrame coords
545 Float_t clusterPads[6] = {0}; // cluster pad info
546
547 // setting values
548 clusters[0] = isect+1; // = isect ????
549 clusters[1] = icham+1; // = ichamber ????
550 clusters[2] = iplan+1; // = iplane ????
551 clusters[3] = time;
552
553 clusterPads[0] = icham+1;
554 clusterPads[1] = isect+1;
555 clusterPads[2] = iplan+1;
556
557 for (Int_t iPad = 0; iPad < 3; iPad++) {
558 clusterSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
559 }
560
561 // neighbouring maximum on right side?
562 if (col < fColMax[iplan] - 2) {
563 if (maximaMatrix->GetSignal(row,col + 2,time) > 0) {
564 for (Int_t iPad = 0; iPad < 5; iPad++) {
565 padSignal[iPad] = digitMatrix->GetSignal(row,col-1+iPad,time);
566 }
567
568 // unfold:
569 ratio = Unfold(epsilon, padSignal);
570
571 // set signal on overlapping pad to ratio
572 clusterSignal[2] *= ratio;
573 }
574 }
575
576 switch (clusteringMethod) {
577 case 1:
578 // method 1: simply center of mass
579 clusterPads[3] = row + 0.5;
580 clusterPads[4] = col - 0.5 + (clusterSignal[2] - clusterSignal[0]) /
581 (clusterSignal[1] + clusterSignal[2] + clusterSignal[3]);
582 clusterPads[5] = time + 0.5;
583
584 nClusters++;
585 break;
586 case 2:
587 // method 2: integral gauss fit on 3 pads
588 TH1F *hPadCharges = new TH1F("hPadCharges", "Charges on center 3 pads"
589 , 5, -1.5, 3.5);
590 for (Int_t iCol = -1; iCol <= 3; iCol++) {
591 if (clusterSignal[iCol] < 1) clusterSignal[iCol] = 1;
592 hPadCharges->Fill(iCol, clusterSignal[iCol]);
593 }
594 hPadCharges->Fit("gaus", "IQ", "SAME", -0.5, 2.5);
595 TF1 *fPadChargeFit = hPadCharges->GetFunction("gaus");
596 Double_t colMean = fPadChargeFit->GetParameter(1);
597
598 clusterPads[3] = row + 0.5;
599 clusterPads[4] = col - 1.5 + colMean;
600 clusterPads[5] = time + 0.5;
601
602 delete hPadCharges;
603
604 nClusters++;
605 break;
606 }
607
608 Float_t clusterCharge = clusterSignal[0]
609 + clusterSignal[1]
610 + clusterSignal[2];
611 clusters[4] = (Int_t)clusterCharge;
612
613 Int_t trackSave[3];
614 for (Int_t iTrack = 0; iTrack < 3; iTrack++) {
615 trackSave[iTrack] = digitMatrix->GetTrack(row,col,time,iTrack);
616 }
617
618 // Calculate cluster position in ALICE refFrame coords
619 // and set array clusterPos to calculated values
620 Pads2XYZ(clusterPads, clusterPos);
621
622 // Add cluster to reconstruction tree
623 AddCluster(trackSave,clusters,clusterPos);
624
625 }
82bbf98a 626
5c7f4665 627 } // time
628 } // col
629 } // row
630
631 printf("AliTRDv1::Digits2Clusters -- Number of clusters found: %d\n",nClusters);
632
633 delete digitMatrix;
634 delete maximaMatrix;
635
636 } // isect
637 } // iplan
638 } // icham
639
640 // Fill the cluster-tree
641 printf("AliTRDv1::Digits2Clusters -- Total number of clusters found: %d\n"
642 ,fClusters->GetEntries());
643 printf("AliTRDv1::Digits2Clusters -- Fill the cluster tree\n");
644 ClusterTree->Fill();
645
646}
647
648//_____________________________________________________________________________
649void AliTRDv1::Init()
650{
651 //
652 // Initialise Transition Radiation Detector after geometry has been built.
653 // Includes the default settings of all parameter for the digitization.
654 //
655
656 AliTRD::Init();
657
658 printf(" Slow simulator\n");
659 if (fSensPlane)
660 printf(" Only plane %d is sensitive\n",fSensPlane);
661 if (fSensChamber)
662 printf(" Only chamber %d is sensitive\n",fSensChamber);
663 if (fSensSector)
664 printf(" Only sector %d is sensitive\n",fSensSector);
665
666 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
667 const Float_t kPoti = 12.1;
668 // Maximum energy (50 keV);
669 const Float_t kEend = 50000.0;
670 // Ermilova distribution for the delta-ray spectrum
671 Float_t Poti = TMath::Log(kPoti);
672 Float_t Eend = TMath::Log(kEend);
673 fDeltaE = new TF1("deltae",Ermilova,Poti,Eend,0);
674
675 // Identifier of the sensitive volume (drift region)
676 fIdSens = gMC->VolId("UL05");
82bbf98a 677
678 // Identifier of the TRD-driftchambers
679 fIdChamber1 = gMC->VolId("UCIO");
680 fIdChamber2 = gMC->VolId("UCIM");
681 fIdChamber3 = gMC->VolId("UCII");
682
5c7f4665 683 // The default parameter for the digitization
684 if (!(fGasGain)) fGasGain = 2.0E3;
685 if (!(fNoise)) fNoise = 3000.;
686 if (!(fChipGain)) fChipGain = 10.;
687 if (!(fADCoutRange)) fADCoutRange = 255.;
688 if (!(fADCinRange)) fADCinRange = 2000.;
689 if (!(fADCthreshold)) fADCthreshold = 1;
690
691 // Transverse and longitudinal diffusion coefficients (Xe/Isobutane)
692 if (!(fDiffusionT)) fDiffusionT = 0.060;
693 if (!(fDiffusionL)) fDiffusionL = 0.017;
694
695 // The default parameter for the clustering
696 if (!(fClusMaxThresh)) fClusMaxThresh = 5.0;
697 if (!(fClusSigThresh)) fClusSigThresh = 2.0;
698 if (!(fClusMethod)) fClusMethod = 1;
699
700 for (Int_t i = 0; i < 80; i++) printf("*");
701 printf("\n");
702
fe4da5cc 703}
704
705//_____________________________________________________________________________
5c7f4665 706Float_t AliTRDv1::PadResponse(Float_t x)
fe4da5cc 707{
708 //
5c7f4665 709 // The pad response for the chevron pads.
710 // We use a simple Gaussian approximation which should be good
711 // enough for our purpose.
fe4da5cc 712 //
d3f347ff 713
5c7f4665 714 // The parameters for the response function
715 const Float_t aa = 0.8872;
716 const Float_t bb = -0.00573;
717 const Float_t cc = 0.454;
718 const Float_t cc2 = cc*cc;
719
720 Float_t pr = aa * (bb + TMath::Exp(-x*x / (2. * cc2)));
721
722 return (pr);
723
724}
725
726//_____________________________________________________________________________
727void AliTRDv1::SetSensPlane(Int_t iplane)
728{
729 //
730 // Defines the hit-sensitive plane (1-6)
731 //
82bbf98a 732
5c7f4665 733 if ((iplane < 0) || (iplane > 6)) {
734 printf("Wrong input value: %d\n",iplane);
735 printf("Use standard setting\n");
736 fSensPlane = 0;
737 fSensSelect = 0;
738 return;
739 }
82bbf98a 740
5c7f4665 741 fSensSelect = 1;
742 fSensPlane = iplane;
82bbf98a 743
5c7f4665 744}
745
746//_____________________________________________________________________________
747void AliTRDv1::SetSensChamber(Int_t ichamber)
748{
749 //
750 // Defines the hit-sensitive chamber (1-5)
751 //
752
753 if ((ichamber < 0) || (ichamber > 5)) {
754 printf("Wrong input value: %d\n",ichamber);
755 printf("Use standard setting\n");
756 fSensChamber = 0;
757 fSensSelect = 0;
758 return;
759 }
760
761 fSensSelect = 1;
762 fSensChamber = ichamber;
763
764}
765
766//_____________________________________________________________________________
767void AliTRDv1::SetSensSector(Int_t isector)
768{
769 //
770 // Defines the hit-sensitive sector (1-18)
771 //
772
773 if ((isector < 0) || (isector > 18)) {
774 printf("Wrong input value: %d\n",isector);
775 printf("Use standard setting\n");
776 fSensSector = 0;
777 fSensSelect = 0;
778 return;
779 }
780
781 fSensSelect = 1;
782 fSensSector = isector;
783
784}
785
786//_____________________________________________________________________________
787void AliTRDv1::StepManager()
788{
789 //
790 // Called at every step in the Transition Radiation Detector version 2.
791 // Slow simulator. Every charged track produces electron cluster as hits
792 // along its path across the drift volume. The step size is set acording
793 // to Bethe-Bloch. The energy distribution of the delta electrons follows
794 // a spectrum taken from Ermilova et al.
795 //
796
797 Int_t iIdSens, icSens;
798 Int_t iIdSpace, icSpace;
799 Int_t iIdChamber, icChamber;
800 Int_t vol[3];
801 Int_t iPid;
802
803 Float_t hits[4];
804 Float_t random[1];
805 Float_t charge;
806 Float_t aMass;
807
808 Double_t pTot;
809 Double_t qTot;
810 Double_t eDelta;
811 Double_t betaGamma, pp;
812
813 TLorentzVector pos, mom;
82bbf98a 814 TClonesArray &lhits = *fHits;
815
5c7f4665 816 const Double_t kBig = 1.0E+12;
817
818 // Ionization energy
819 const Float_t kWion = 22.04;
820 // Maximum energy for e+ e- g for the step-size calculation
821 const Float_t kPTotMax = 0.002;
822 // Plateau value of the energy-loss for electron in xenon
823 // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
824 //const Double_t kPlateau = 1.70;
825 // the averaged value (26/3/99)
826 const Float_t kPlateau = 1.55;
827 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
828 const Float_t kPrim = 48.0;
829 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
830 const Float_t kPoti = 12.1;
831
832 // Set the maximum step size to a very large number for all
833 // neutral particles and those outside the driftvolume
834 gMC->SetMaxStep(kBig);
835
836 // Use only charged tracks
837 if (( gMC->TrackCharge() ) &&
838 (!gMC->IsTrackStop() ) &&
839 (!gMC->IsTrackDisappeared())) {
fe4da5cc 840
5c7f4665 841 // Inside a sensitive volume?
82bbf98a 842 iIdSens = gMC->CurrentVolID(icSens);
843 if (iIdSens == fIdSens) {
844
82bbf98a 845 iIdSpace = gMC->CurrentVolOffID(4,icSpace );
846 iIdChamber = gMC->CurrentVolOffID(1,icChamber);
fe4da5cc 847
5c7f4665 848 // Calculate the energy of the delta-electrons
849 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
850 eDelta = TMath::Max(eDelta,0.0);
851
852 // The number of secondary electrons created
853 qTot = (Double_t) ((Int_t) (eDelta / kWion) + 1);
854
855 // The hit coordinates and charge
856 gMC->TrackPosition(pos);
857 hits[0] = pos[0];
858 hits[1] = pos[1];
859 hits[2] = pos[2];
860 hits[3] = qTot;
861
fe4da5cc 862 // The sector number
5c7f4665 863 Float_t phi = pos[1] != 0 ? TMath::Atan2(pos[0],pos[1]) : (pos[0] > 0 ? 180. : 0.);
864 vol[0] = ((Int_t) (phi / 20)) + 1;
82bbf98a 865
d3f347ff 866 // The chamber number
867 // 1: outer left
82bbf98a 868 // 2: middle left
d3f347ff 869 // 3: inner
82bbf98a 870 // 4: middle right
d3f347ff 871 // 5: outer right
82bbf98a 872 if (iIdChamber == fIdChamber1)
873 vol[1] = (hits[2] < 0 ? 1 : 5);
874 else if (iIdChamber == fIdChamber2)
875 vol[1] = (hits[2] < 0 ? 2 : 4);
876 else if (iIdChamber == fIdChamber3)
d3f347ff 877 vol[1] = 3;
82bbf98a 878
fe4da5cc 879 // The plane number
82bbf98a 880 vol[2] = icChamber - TMath::Nint((Float_t) (icChamber / 7)) * 6;
881
5c7f4665 882 // Check on selected volumes
883 Int_t addthishit = 1;
884 if (fSensSelect) {
885 if ((fSensPlane) && (vol[2] != fSensPlane )) addthishit = 0;
886 if ((fSensChamber) && (vol[1] != fSensChamber)) addthishit = 0;
887 if ((fSensSector) && (vol[0] != fSensSector )) addthishit = 0;
888 }
889
890 // Add this hit
891 if (addthishit) {
892
893 new(lhits[fNhits++]) AliTRDhit(fIshunt,gAlice->CurrentTrack(),vol,hits);
894
895 // The energy loss according to Bethe Bloch
896 gMC->TrackMomentum(mom);
897 pTot = mom.Rho();
898 iPid = gMC->TrackPid();
899 if ( (iPid > 3) ||
900 ((iPid <= 3) && (pTot < kPTotMax))) {
901 aMass = gMC->TrackMass();
902 betaGamma = pTot / aMass;
903 pp = kPrim * BetheBloch(betaGamma);
904 // Take charge > 1 into account
905 charge = gMC->TrackCharge();
906 if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
907 }
908 // Electrons above 20 Mev/c are at the plateau
909 else {
910 pp = kPrim * kPlateau;
911 }
912
913 // Calculate the maximum step size for the next tracking step
914 if (pp > 0) {
915 do
916 gMC->Rndm(random,1);
917 while ((random[0] == 1.) || (random[0] == 0.));
918 gMC->SetMaxStep( - TMath::Log(random[0]) / pp);
919 }
920
921 }
922 else {
923 // set step size to maximal value
924 gMC->SetMaxStep(kBig);
925 }
d3f347ff 926
927 }
928
5c7f4665 929 }
930
931}
932
933//_____________________________________________________________________________
934Double_t AliTRDv1::BetheBloch(Double_t bg)
935{
936 //
937 // Parametrization of the Bethe-Bloch-curve
938 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
939 //
940
941 // This parameters have been adjusted to averaged values from GEANT
942 const Double_t kP1 = 7.17960e-02;
943 const Double_t kP2 = 8.54196;
944 const Double_t kP3 = 1.38065e-06;
945 const Double_t kP4 = 5.30972;
946 const Double_t kP5 = 2.83798;
947
948 // This parameters have been adjusted to Xe-data found in:
949 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
950 //const Double_t kP1 = 0.76176E-1;
951 //const Double_t kP2 = 10.632;
952 //const Double_t kP3 = 3.17983E-6;
953 //const Double_t kP4 = 1.8631;
954 //const Double_t kP5 = 1.9479;
955
956 if (bg > 0) {
957 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
958 Double_t aa = TMath::Power(yy,kP4);
959 Double_t bb = TMath::Power((1./bg),kP5);
960 bb = TMath::Log(kP3 + bb);
961 return ((kP2 - aa - bb)*kP1 / aa);
962 }
963 else
964 return 0;
d3f347ff 965
fe4da5cc 966}
5c7f4665 967
968//_____________________________________________________________________________
969Double_t Ermilova(Double_t *x, Double_t *)
970{
971 //
972 // Calculates the delta-ray energy distribution according to Ermilova.
973 // Logarithmic scale !
974 //
975
976 Double_t energy;
977 Double_t dpos;
978 Double_t dnde;
979
980 Int_t pos1, pos2;
981
982 const Int_t nV = 31;
983
984 Float_t vxe[nV] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
985 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
986 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
987 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
988 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
989 , 9.4727, 9.9035,10.3735,10.5966,10.8198
990 ,11.5129 };
991
992 Float_t vye[nV] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
993 , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
994 , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
995 , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
996 , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
997 , 0.04 , 0.023, 0.015, 0.011, 0.01
998 , 0.004 };
999
1000 energy = x[0];
1001
1002 // Find the position
1003 pos1 = pos2 = 0;
1004 dpos = 0;
1005 do {
1006 dpos = energy - vxe[pos2++];
1007 }
1008 while (dpos > 0);
1009 pos2--;
1010 if (pos2 > nV) pos2 = nV;
1011 pos1 = pos2 - 1;
1012
1013 // Differentiate between the sampling points
1014 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1015
1016 return dnde;
1017
1018}
1019
1020//_____________________________________________________________________________
1021void AliTRDv1::Pads2XYZ(Float_t *pads, Float_t *pos)
1022{
1023 // Method to convert pad coordinates (row,col,time)
1024 // into ALICE reference frame coordinates (x,y,z)
1025
1026 Int_t chamber = (Int_t) pads[0]; // chamber info (1-5)
1027 Int_t sector = (Int_t) pads[1]; // sector info (1-18)
1028 Int_t plane = (Int_t) pads[2]; // plane info (1-6)
1029
1030 Int_t icham = chamber - 1; // chamber info (0-4)
1031 Int_t isect = sector - 1; // sector info (0-17)
1032 Int_t iplan = plane - 1; // plane info (0-5)
1033
1034 Float_t padRow = pads[3]; // Pad Row position
1035 Float_t padCol = pads[4]; // Pad Column position
1036 Float_t timeSlice = pads[5]; // Time "position"
1037
1038 // calculate (x,y) position in rotated chamber
1039 Float_t yRot = fCol0[iplan] + padCol * fColPadSize;
1040 Float_t xRot = fTime0[iplan] + timeSlice * fTimeBinSize;
1041 // calculate z-position:
1042 Float_t z = fRow0[iplan][icham][isect] + padRow * fRowPadSize;
1043
1044 /**
1045 rotate chamber back to original position
1046 1. mirror at y-axis, 2. rotate back to position (-phi)
1047 / cos(phi) -sin(phi) \ / -1 0 \ / -cos(phi) -sin(phi) \
1048 \ sin(phi) cos(phi) / * \ 0 1 / = \ -sin(phi) cos(phi) /
1049 **/
1050 //Float_t phi = 2*kPI / kNsect * ((Float_t) sector - 0.5);
1051 //Float_t x = -xRot * TMath::Cos(phi) - yRot * TMath::Sin(phi);
1052 //Float_t y = -xRot * TMath::Sin(phi) + yRot * TMath::Cos(phi);
1053 Float_t phi = 2*kPI / kNsect * ((Float_t) sector - 0.5);
1054 Float_t x = -xRot * TMath::Cos(phi) + yRot * TMath::Sin(phi);
1055 Float_t y = xRot * TMath::Sin(phi) + yRot * TMath::Cos(phi);
1056
1057 // Setting values
1058 pos[0] = x;
1059 pos[1] = y;
1060 pos[2] = z;
1061
1062}
1063
1064//_____________________________________________________________________________
1065Float_t AliTRDv1::Unfold(Float_t eps, Float_t* padSignal)
1066{
1067 // Method to unfold neighbouring maxima.
1068 // The charge ratio on the overlapping pad is calculated
1069 // until there is no more change within the range given by eps.
1070 // The resulting ratio is then returned to the calling method.
1071
1072 Int_t itStep = 0; // count iteration steps
1073
1074 Float_t ratio = 0.5; // start value for ratio
1075 Float_t prevRatio = 0; // store previous ratio
1076
1077 Float_t newLeftSignal[3] = {0}; // array to store left cluster signal
1078 Float_t newRightSignal[3] = {0}; // array to store right cluster signal
1079
1080 // start iteration:
1081 while ((TMath::Abs(prevRatio - ratio) > eps) && (itStep < 10)) {
1082
1083 itStep++;
1084 prevRatio = ratio;
1085
1086 // cluster position according to charge ratio
1087 Float_t maxLeft = (ratio*padSignal[2] - padSignal[0]) /
1088 (padSignal[0] + padSignal[1] + ratio*padSignal[2]);
1089 Float_t maxRight = (padSignal[4] - (1-ratio)*padSignal[2]) /
1090 ((1-ratio)*padSignal[2] + padSignal[3] + padSignal[4]);
1091
1092 // set cluster charge ratio
1093 Float_t ampLeft = padSignal[1];
1094 Float_t ampRight = padSignal[3];
1095
1096 // apply pad response to parameters
1097 newLeftSignal[0] = ampLeft*PadResponse(-1 - maxLeft);
1098 newLeftSignal[1] = ampLeft*PadResponse( 0 - maxLeft);
1099 newLeftSignal[2] = ampLeft*PadResponse( 1 - maxLeft);
1100
1101 newRightSignal[0] = ampRight*PadResponse(-1 - maxRight);
1102 newRightSignal[1] = ampRight*PadResponse( 0 - maxRight);
1103 newRightSignal[2] = ampRight*PadResponse( 1 - maxRight);
1104
1105 // calculate new overlapping ratio
1106 ratio = newLeftSignal[2]/(newLeftSignal[2] + newRightSignal[0]);
1107
1108 }
1109
1110 return ratio;
1111
1112}
1113