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[u/mrichter/AliRoot.git] / TRD / AliTRDv1.cxx
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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
88cb7938 16/* $Id$ */
4c039060 17
030b4415 18////////////////////////////////////////////////////////////////////////////
19// //
20// Transition Radiation Detector version 1 -- slow simulator //
21// //
22////////////////////////////////////////////////////////////////////////////
fe4da5cc 23
769257f4 24#include <stdlib.h>
25
793ff80c 26#include <TF1.h>
1819f4bb 27#include <TLorentzVector.h>
88cb7938 28#include <TMath.h>
29#include <TRandom.h>
30#include <TVector.h>
31#include <TVirtualMC.h>
f57bb418 32#include <TGeoManager.h>
170c35f1 33#include <TGeoPhysicalNode.h>
fe4da5cc 34
d3f347ff 35#include "AliConst.h"
45160b1f 36#include "AliLog.h"
e6add757 37#include "AliTrackReference.h"
45160b1f 38#include "AliMC.h"
88cb7938 39#include "AliRun.h"
030b4415 40
88cb7938 41#include "AliTRDgeometry.h"
793ff80c 42#include "AliTRDhit.h"
cb2f9e9b 43#include "AliTRDsimTR.h"
88cb7938 44#include "AliTRDv1.h"
851d3db9 45
fe4da5cc 46ClassImp(AliTRDv1)
8230f242 47
48//_____________________________________________________________________________
030b4415 49AliTRDv1::AliTRDv1()
50 :AliTRD()
51 ,fTRon(kFALSE)
52 ,fTR(NULL)
53 ,fTypeOfStepManager(0)
54 ,fStepSize(0)
55 ,fDeltaE(NULL)
56 ,fDeltaG(NULL)
57 ,fTrackLength0(0)
58 ,fPrimaryTrackPid(0)
8230f242 59{
60 //
61 // Default constructor
62 //
63
8230f242 64}
65
fe4da5cc 66//_____________________________________________________________________________
67AliTRDv1::AliTRDv1(const char *name, const char *title)
030b4415 68 :AliTRD(name,title)
69 ,fTRon(kTRUE)
70 ,fTR(NULL)
67c47633 71 ,fTypeOfStepManager(2)
030b4415 72 ,fStepSize(0.1)
73 ,fDeltaE(NULL)
74 ,fDeltaG(NULL)
75 ,fTrackLength0(0)
76 ,fPrimaryTrackPid(0)
fe4da5cc 77{
78 //
851d3db9 79 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 80 //
82bbf98a 81
5c7f4665 82 SetBufferSize(128000);
83
84}
85
86//_____________________________________________________________________________
87AliTRDv1::~AliTRDv1()
88{
dd9a6ee3 89 //
90 // AliTRDv1 destructor
91 //
82bbf98a 92
030b4415 93 if (fDeltaE) {
94 delete fDeltaE;
95 fDeltaE = 0;
96 }
97
98 if (fDeltaG) {
99 delete fDeltaG;
100 fDeltaG = 0;
101 }
102
103 if (fTR) {
104 delete fTR;
105 fTR = 0;
106 }
82bbf98a 107
fe4da5cc 108}
109
dd9a6ee3 110//_____________________________________________________________________________
f57bb418 111void AliTRDv1::AddAlignableVolumes() const
112{
113 //
114 // Create entries for alignable volumes associating the symbolic volume
115 // name with the corresponding volume path. Needs to be syncronized with
116 // eventual changes in the geometry.
117 //
118
119 TString volPath;
120 TString symName;
121
122 TString vpStr = "ALIC_1/B077_1/BSEGMO";
123 TString vpApp1 = "_1/BTRD";
124 TString vpApp2 = "_1";
125 TString vpApp3 = "/UTR1_1/UTS1_1/UTI1_1/UT";
126
127 TString snStr = "TRD/sm";
128 TString snApp1 = "/st";
129 TString snApp2 = "/pl";
130
131 //
132 // The super modules
133 // The symbolic names are: TRD/sm00
134 // ...
135 // TRD/sm17
136 //
137 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
138
139 volPath = vpStr;
140 volPath += isect;
141 volPath += vpApp1;
142 volPath += isect;
143 volPath += vpApp2;
144
145 symName = snStr;
146 symName += Form("%02d",isect);
147
148 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
149
150 }
151
152 //
153 // The readout chambers
154 // The symbolic names are: TRD/sm00/st0/pl0
155 // ...
156 // TRD/sm17/st4/pl5
157 //
158 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
159 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
160 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
161
162 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
163
164 volPath = vpStr;
165 volPath += isect;
166 volPath += vpApp1;
167 volPath += isect;
168 volPath += vpApp2;
169 volPath += vpApp3;
170 volPath += Form("%02d",idet);
171 volPath += vpApp2;
172
173 symName = snStr;
174 symName += Form("%02d",isect);
175 symName += snApp1;
176 symName += icham;
177 symName += snApp2;
178 symName += iplan;
179
51a5f1d0 180 TGeoPNEntry *alignableEntry =
181 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
f57bb418 182
170c35f1 183 // Add the tracking to local matrix following the TPC example
170c35f1 184
51a5f1d0 185 if (alignableEntry) {
186 const char *path = alignableEntry->GetTitle();
187 if (!gGeoManager->cd(path)) {
188 AliFatal(Form("Volume path %s not valid!",path));
189 }
190 TGeoHMatrix *globMatrix = gGeoManager->GetCurrentMatrix();
191 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
192 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
193 t2lMatrix->RotateZ(sectorAngle);
194 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
195 alignableEntry->SetMatrix(t2lMatrix);
196 }
197 else {
198 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
199 }
f57bb418 200 }
201 }
202 }
203
204}
205
206//_____________________________________________________________________________
fe4da5cc 207void AliTRDv1::CreateGeometry()
208{
209 //
851d3db9 210 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 211 // This version covers the full azimuth.
d3f347ff 212 //
213
82bbf98a 214 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 215 AliModule* frame = gAlice->GetModule("FRAME");
030b4415 216 if (!frame) {
217 AliError("TRD needs FRAME to be present\n");
218 return;
219 }
d3f347ff 220
82bbf98a 221 // Define the chambers
222 AliTRD::CreateGeometry();
d3f347ff 223
fe4da5cc 224}
225
226//_____________________________________________________________________________
227void AliTRDv1::CreateMaterials()
228{
229 //
851d3db9 230 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 231 //
82bbf98a 232
d3f347ff 233 AliTRD::CreateMaterials();
82bbf98a 234
fe4da5cc 235}
236
237//_____________________________________________________________________________
793ff80c 238void AliTRDv1::CreateTRhit(Int_t det)
239{
240 //
241 // Creates an electron cluster from a TR photon.
242 // The photon is assumed to be created a the end of the radiator. The
243 // distance after which it deposits its energy takes into account the
244 // absorbtion of the entrance window and of the gas mixture in drift
245 // volume.
246 //
247
793ff80c 248 // Ionization energy
bc327ce2 249 const Float_t kWion = 23.53;
793ff80c 250
251 // Maximum number of TR photons per track
252 const Int_t kNTR = 50;
253
030b4415 254 TLorentzVector mom;
255 TLorentzVector pos;
793ff80c 256
ce0d6231 257 Float_t eTR[kNTR];
258 Int_t nTR;
793ff80c 259
ce0d6231 260 // Create TR photons
261 gMC->TrackMomentum(mom);
262 Float_t pTot = mom.Rho();
263 fTR->CreatePhotons(11,pTot,nTR,eTR);
264 if (nTR > kNTR) {
265 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
266 }
f73816f5 267
ce0d6231 268 // Loop through the TR photons
269 for (Int_t iTR = 0; iTR < nTR; iTR++) {
793ff80c 270
ce0d6231 271 Float_t energyMeV = eTR[iTR] * 0.001;
272 Float_t energyeV = eTR[iTR] * 1000.0;
273 Float_t absLength = 0.0;
274 Float_t sigma = 0.0;
793ff80c 275
ce0d6231 276 // Take the absorbtion in the entrance window into account
277 Double_t muMy = fTR->GetMuMy(energyMeV);
278 sigma = muMy * fFoilDensity;
279 if (sigma > 0.0) {
280 absLength = gRandom->Exp(1.0/sigma);
281 if (absLength < AliTRDgeometry::MyThick()) {
842287f2 282 continue;
283 }
ce0d6231 284 }
285 else {
286 continue;
287 }
793ff80c 288
ce0d6231 289 // The absorbtion cross sections in the drift gas
290 // Gas-mixture (Xe/CO2)
291 Double_t muXe = fTR->GetMuXe(energyMeV);
292 Double_t muCO = fTR->GetMuCO(energyMeV);
293 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
294
295 // The distance after which the energy of the TR photon
296 // is deposited.
297 if (sigma > 0.0) {
298 absLength = gRandom->Exp(1.0/sigma);
299 if (absLength > (AliTRDgeometry::DrThick()
300 + AliTRDgeometry::AmThick())) {
842287f2 301 continue;
302 }
ce0d6231 303 }
304 else {
305 continue;
306 }
793ff80c 307
ce0d6231 308 // The position of the absorbtion
309 Float_t posHit[3];
310 gMC->TrackPosition(pos);
311 posHit[0] = pos[0] + mom[0] / pTot * absLength;
312 posHit[1] = pos[1] + mom[1] / pTot * absLength;
313 posHit[2] = pos[2] + mom[2] / pTot * absLength;
793ff80c 314
ce0d6231 315 // Create the charge
316 Int_t q = ((Int_t) (energyeV / kWion));
793ff80c 317
ce0d6231 318 // Add the hit to the array. TR photon hits are marked
319 // by negative charge
320 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
321 ,det
322 ,posHit
323 ,-q
25ca55ce 324 ,gMC->TrackTime()*1.0e06
d4c6453d 325 ,kTRUE);
793ff80c 326
327 }
328
329}
330
331//_____________________________________________________________________________
5c7f4665 332void AliTRDv1::Init()
333{
334 //
335 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 336 //
337
338 AliTRD::Init();
339
45160b1f 340 AliDebug(1,"Slow simulator\n");
bd0f8685 341
342 // Switch on TR simulation as default
343 if (!fTRon) {
45160b1f 344 AliInfo("TR simulation off");
bd0f8685 345 }
346 else {
cb2f9e9b 347 fTR = new AliTRDsimTR();
bd0f8685 348 }
5c7f4665 349
350 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
351 const Float_t kPoti = 12.1;
352 // Maximum energy (50 keV);
353 const Float_t kEend = 50000.0;
354 // Ermilova distribution for the delta-ray spectrum
030b4415 355 Float_t poti = TMath::Log(kPoti);
356 Float_t eEnd = TMath::Log(kEend);
a328fff9 357
358 // Ermilova distribution for the delta-ray spectrum
c4214bc0 359 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
a328fff9 360
361 // Geant3 distribution for the delta-ray spectrum
c4214bc0 362 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
5c7f4665 363
45160b1f 364 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
5c7f4665 365
fe4da5cc 366}
367
368//_____________________________________________________________________________
5c7f4665 369void AliTRDv1::StepManager()
370{
371 //
c4214bc0 372 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 373 // along its path across the drift volume.
374 //
375
376 switch (fTypeOfStepManager) {
a6dd11e9 377 case 0:
378 StepManagerErmilova();
379 break;
380 case 1:
381 StepManagerGeant();
382 break;
383 case 2:
384 StepManagerFixedStep();
385 break;
386 default:
387 AliWarning("Not a valid Step Manager.");
a328fff9 388 }
389
390}
391
392//_____________________________________________________________________________
393void AliTRDv1::SelectStepManager(Int_t t)
394{
395 //
396 // Selects a step manager type:
397 // 0 - Ermilova
398 // 1 - Geant3
399 // 2 - Fixed step size
400 //
401
a328fff9 402 fTypeOfStepManager = t;
45160b1f 403 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
a328fff9 404
405}
406
407//_____________________________________________________________________________
408void AliTRDv1::StepManagerGeant()
409{
410 //
c4214bc0 411 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 412 // along its path across the drift volume. The step size is set acording
413 // to Bethe-Bloch. The energy distribution of the delta electrons follows
414 // a spectrum taken from Geant3.
415 //
f2e3a0b5 416 // Version by A. Bercuci
417 //
418
c4214bc0 419 Int_t pla = 0;
420 Int_t cha = 0;
421 Int_t sec = 0;
422 Int_t det = 0;
423 Int_t iPdg;
424 Int_t qTot;
425
426 Float_t hits[3];
427 Float_t charge;
428 Float_t aMass;
429
030b4415 430 Double_t pTot = 0;
c4214bc0 431 Double_t eDelta;
030b4415 432 Double_t betaGamma;
433 Double_t pp;
f2e3a0b5 434 Double_t stepSize = 0;
c4214bc0 435
436 Bool_t drRegion = kFALSE;
437 Bool_t amRegion = kFALSE;
438
2c8bf4aa 439 TString cIdPath;
440 Char_t cIdSector[3];
441 cIdSector[2] = 0;
442
c4214bc0 443 TString cIdCurrent;
444 TString cIdSensDr = "J";
445 TString cIdSensAm = "K";
446 Char_t cIdChamber[3];
447 cIdChamber[2] = 0;
448
030b4415 449 TLorentzVector pos;
450 TLorentzVector mom;
c4214bc0 451
030b4415 452 TArrayI processes;
f2e3a0b5 453
c4214bc0 454 const Int_t kNplan = AliTRDgeometry::Nplan();
455 const Int_t kNcham = AliTRDgeometry::Ncham();
456 const Int_t kNdetsec = kNplan * kNcham;
457
030b4415 458 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 459 const Float_t kWion = 23.53; // Ionization energy
c4214bc0 460 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
461
462 // Minimum energy for the step size adjustment
463 const Float_t kEkinMinStep = 1.0e-5;
464 // energy threshold for production of delta electrons
f2e3a0b5 465 const Float_t kECut = 1.0e4;
466 // Parameters entering the parametrized range for delta electrons
030b4415 467 const Float_t kRa = 5.37e-4;
f2e3a0b5 468 const Float_t kRb = 0.9815;
030b4415 469 const Float_t kRc = 3.123e-3;
f2e3a0b5 470 // Gas density -> To be made user adjustable !
030b4415 471 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
472 const Float_t kRho = 0.004945 ;
a328fff9 473
c4214bc0 474 // Plateau value of the energy-loss for electron in xenon
030b4415 475 // The averaged value (26/3/99)
c4214bc0 476 const Float_t kPlateau = 1.55;
030b4415 477 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
478 const Float_t kPrim = 19.34;
c4214bc0 479 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
480 const Float_t kPoti = 12.1;
030b4415 481 // PDG code electron
482 const Int_t kPdgElectron = 11;
c4214bc0 483
484 // Set the maximum step size to a very large number for all
485 // neutral particles and those outside the driftvolume
486 gMC->SetMaxStep(kBig);
487
488 // Use only charged tracks
489 if (( gMC->TrackCharge() ) &&
c4214bc0 490 (!gMC->IsTrackDisappeared())) {
491
492 // Inside a sensitive volume?
493 drRegion = kFALSE;
494 amRegion = kFALSE;
495 cIdCurrent = gMC->CurrentVolName();
496 if (cIdSensDr == cIdCurrent[1]) {
497 drRegion = kTRUE;
498 }
499 if (cIdSensAm == cIdCurrent[1]) {
500 amRegion = kTRUE;
501 }
502 if (drRegion || amRegion) {
a328fff9 503
c4214bc0 504 // The hit coordinates and charge
505 gMC->TrackPosition(pos);
506 hits[0] = pos[0];
507 hits[1] = pos[1];
508 hits[2] = pos[2];
509
2c8bf4aa 510 // The sector number (0 - 17), according to standard coordinate system
511 cIdPath = gGeoManager->GetPath();
512 cIdSector[0] = cIdPath[21];
513 cIdSector[1] = cIdPath[22];
514 sec = atoi(cIdSector);
c4214bc0 515
516 // The plane and chamber number
030b4415 517 cIdChamber[0] = cIdCurrent[2];
518 cIdChamber[1] = cIdCurrent[3];
c4214bc0 519 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 520 cha = ((Int_t) idChamber / kNplan);
c4214bc0 521 pla = ((Int_t) idChamber % kNplan);
522
ce0d6231 523 // The detector number
524 det = fGeometry->GetDetector(pla,cha,sec);
c4214bc0 525
ce0d6231 526 // Special hits only in the drift region
527 if ((drRegion) &&
528 (gMC->IsTrackEntering())) {
c4214bc0 529
ce0d6231 530 // Create a track reference at the entrance of each
531 // chamber that contains the momentum components of the particle
532 gMC->TrackMomentum(mom);
e6add757 533 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
c4214bc0 534
ce0d6231 535 // Create the hits from TR photons if electron/positron is
536 // entering the drift volume
537 if ((fTR) &&
538 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
539 CreateTRhit(det);
540 }
f2e3a0b5 541
ce0d6231 542 }
543 else if ((amRegion) &&
544 (gMC->IsTrackExiting())) {
f2e3a0b5 545
ce0d6231 546 // Create a track reference at the exit of each
547 // chamber that contains the momentum components of the particle
548 gMC->TrackMomentum(mom);
e6add757 549 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
c4214bc0 550
ce0d6231 551 }
c4214bc0 552
ce0d6231 553 // Calculate the energy of the delta-electrons
554 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
555 // take into account correlation with the underlying GEANT tracking
556 // mechanism. see
557 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
558 //
559 // determine the most significant process (last on the processes list)
560 // which caused this hit
561 gMC->StepProcesses(processes);
562 Int_t nofprocesses = processes.GetSize();
563 Int_t pid;
564 if (!nofprocesses) {
565 pid = 0;
566 }
567 else {
568 pid = processes[nofprocesses-1];
569 }
f2e3a0b5 570
ce0d6231 571 // Generate Edep according to GEANT parametrisation
572 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
573 eDelta = TMath::Max(eDelta,0.0);
574 Float_t prRange = 0.0;
575 Float_t range = gMC->TrackLength() - fTrackLength0;
576 // merge GEANT tracker information with locally cooked one
577 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
578 if (pid == 27) {
579 if (eDelta >= kECut) {
580 prRange = kRa * eDelta * 0.001
581 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
582 if (prRange >= (3.7 - range)) {
583 eDelta *= 0.1;
584 }
585 }
586 }
587 else if (pid == 1) {
588 if (eDelta < kECut) {
589 eDelta *= 0.5;
590 }
591 else {
592 prRange = kRa * eDelta * 0.001
593 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
594 if (prRange >= ((AliTRDgeometry::DrThick()
595 + AliTRDgeometry::AmThick()) - range)) {
596 eDelta *= 0.05;
597 }
598 else {
f2e3a0b5 599 eDelta *= 0.5;
ce0d6231 600 }
601 }
602 }
f2e3a0b5 603 else {
604 eDelta = 0.0;
ce0d6231 605 }
606 }
607 else {
608 eDelta = 0.0;
609 }
c4214bc0 610
ce0d6231 611 // Generate the electron cluster size
612 if (eDelta > 0.0) {
f2e3a0b5 613
ce0d6231 614 qTot = ((Int_t) (eDelta / kWion) + 1);
615
616 // Create a new dEdx hit
030b4415 617 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
618 ,det
619 ,hits
620 ,qTot
25ca55ce 621 ,gMC->TrackTime()*1.0e06
030b4415 622 ,drRegion);
c4214bc0 623
ce0d6231 624 }
625
626 // Calculate the maximum step size for the next tracking step
627 // Produce only one hit if Ekin is below cutoff
628 aMass = gMC->TrackMass();
629 if ((gMC->Etot() - aMass) > kEkinMinStep) {
630
631 // The energy loss according to Bethe Bloch
632 iPdg = TMath::Abs(gMC->TrackPid());
633 if ((iPdg != kPdgElectron) ||
634 ((iPdg == kPdgElectron) &&
635 (pTot < kPTotMaxEl))) {
636 gMC->TrackMomentum(mom);
637 pTot = mom.Rho();
638 betaGamma = pTot / aMass;
639 pp = BetheBlochGeant(betaGamma);
640 // Take charge > 1 into account
641 charge = gMC->TrackCharge();
642 if (TMath::Abs(charge) > 1) {
643 pp = pp * charge*charge;
644 }
645 }
646 else {
647 // Electrons above 20 Mev/c are at the plateau
648 pp = kPrim * kPlateau;
649 }
f2e3a0b5 650
ce0d6231 651 Int_t nsteps = 0;
652 do {
653 nsteps = gRandom->Poisson(pp);
654 } while(!nsteps);
655 stepSize = 1.0 / nsteps;
656 gMC->SetMaxStep(stepSize);
f2e3a0b5 657
c4214bc0 658 }
f2e3a0b5 659
c4214bc0 660 }
f2e3a0b5 661
c4214bc0 662 }
f2e3a0b5 663
a328fff9 664}
665
666//_____________________________________________________________________________
667void AliTRDv1::StepManagerErmilova()
668{
669 //
670 // Slow simulator. Every charged track produces electron cluster as hits
5c7f4665 671 // along its path across the drift volume. The step size is set acording
672 // to Bethe-Bloch. The energy distribution of the delta electrons follows
673 // a spectrum taken from Ermilova et al.
674 //
675
851d3db9 676 Int_t pla = 0;
677 Int_t cha = 0;
678 Int_t sec = 0;
793ff80c 679 Int_t det = 0;
851d3db9 680 Int_t iPdg;
793ff80c 681 Int_t qTot;
5c7f4665 682
793ff80c 683 Float_t hits[3];
a5cadd36 684 Double_t random[1];
5c7f4665 685 Float_t charge;
686 Float_t aMass;
687
030b4415 688 Double_t pTot = 0.0;
5c7f4665 689 Double_t eDelta;
030b4415 690 Double_t betaGamma;
691 Double_t pp;
f73816f5 692 Double_t stepSize;
5c7f4665 693
332e9569 694 Bool_t drRegion = kFALSE;
695 Bool_t amRegion = kFALSE;
696
2c8bf4aa 697 TString cIdPath;
698 Char_t cIdSector[3];
699 cIdSector[2] = 0;
700
332e9569 701 TString cIdCurrent;
702 TString cIdSensDr = "J";
703 TString cIdSensAm = "K";
593a9fc3 704 Char_t cIdChamber[3];
705 cIdChamber[2] = 0;
332e9569 706
030b4415 707 TLorentzVector pos;
708 TLorentzVector mom;
82bbf98a 709
332e9569 710 const Int_t kNplan = AliTRDgeometry::Nplan();
e644678a 711 const Int_t kNcham = AliTRDgeometry::Ncham();
712 const Int_t kNdetsec = kNplan * kNcham;
713
030b4415 714 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 715 const Float_t kWion = 23.53; // Ionization energy
a328fff9 716 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
5c7f4665 717
f73816f5 718 // Minimum energy for the step size adjustment
719 const Float_t kEkinMinStep = 1.0e-5;
a328fff9 720
5c7f4665 721 // Plateau value of the energy-loss for electron in xenon
030b4415 722 // The averaged value (26/3/99)
a3c76cdc 723 const Float_t kPlateau = 1.55;
030b4415 724 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
725 const Float_t kPrim = 48.0;
5c7f4665 726 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 727 const Float_t kPoti = 12.1;
030b4415 728 // PDG code electron
729 const Int_t kPdgElectron = 11;
5c7f4665 730
731 // Set the maximum step size to a very large number for all
732 // neutral particles and those outside the driftvolume
733 gMC->SetMaxStep(kBig);
734
735 // Use only charged tracks
736 if (( gMC->TrackCharge() ) &&
5c7f4665 737 (!gMC->IsTrackDisappeared())) {
fe4da5cc 738
5c7f4665 739 // Inside a sensitive volume?
332e9569 740 drRegion = kFALSE;
741 amRegion = kFALSE;
742 cIdCurrent = gMC->CurrentVolName();
e6674585 743 if (cIdSensDr == cIdCurrent[1]) {
332e9569 744 drRegion = kTRUE;
745 }
e6674585 746 if (cIdSensAm == cIdCurrent[1]) {
332e9569 747 amRegion = kTRUE;
748 }
749 if (drRegion || amRegion) {
fe4da5cc 750
5c7f4665 751 // The hit coordinates and charge
752 gMC->TrackPosition(pos);
753 hits[0] = pos[0];
754 hits[1] = pos[1];
755 hits[2] = pos[2];
5c7f4665 756
2c8bf4aa 757 // The sector number (0 - 17), according to standard coordinate system
758 cIdPath = gGeoManager->GetPath();
759 cIdSector[0] = cIdPath[21];
760 cIdSector[1] = cIdPath[22];
761 sec = atoi(cIdSector);
82bbf98a 762
332e9569 763 // The plane and chamber number
764 cIdChamber[0] = cIdCurrent[2];
765 cIdChamber[1] = cIdCurrent[3];
e644678a 766 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 767 cha = ((Int_t) idChamber / kNplan);
332e9569 768 pla = ((Int_t) idChamber % kNplan);
82bbf98a 769
ce0d6231 770 // The detector number
771 det = fGeometry->GetDetector(pla,cha,sec);
5c7f4665 772
ce0d6231 773 // Special hits only in the drift region
774 if ((drRegion) &&
775 (gMC->IsTrackEntering())) {
5c7f4665 776
ce0d6231 777 // Create a track reference at the entrance of each
778 // chamber that contains the momentum components of the particle
779 gMC->TrackMomentum(mom);
e6add757 780 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
793ff80c 781
ce0d6231 782 // Create the hits from TR photons if electron/positron is
783 // entering the drift volume
784 if ((fTR) &&
785 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
786 CreateTRhit(det);
787 }
f73816f5 788
ce0d6231 789 }
790 else if ((amRegion) &&
791 (gMC->IsTrackExiting())) {
f73816f5 792
ce0d6231 793 // Create a track reference at the exit of each
794 // chamber that contains the momentum components of the particle
795 gMC->TrackMomentum(mom);
e6add757 796 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
f73816f5 797
ce0d6231 798 }
799
800 // Calculate the energy of the delta-electrons
801 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
802 eDelta = TMath::Max(eDelta,0.0);
803
804 // Generate the electron cluster size
805 if (eDelta > 0.0) {
806
807 qTot = ((Int_t) (eDelta / kWion) + 1);
f73816f5 808
030b4415 809 // Create a new dEdx hit
332e9569 810 if (drRegion) {
a328fff9 811 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 812 ,det
813 ,hits
814 ,qTot
25ca55ce 815 ,gMC->TrackTime()*1.0e06
030b4415 816 ,kTRUE);
817 }
5c7f4665 818 else {
a328fff9 819 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 820 ,det
821 ,hits
822 ,qTot
25ca55ce 823 ,gMC->TrackTime()*1.0e06
030b4415 824 ,kFALSE);
825 }
f73816f5 826
ce0d6231 827 }
828
829 // Calculate the maximum step size for the next tracking step
830 // Produce only one hit if Ekin is below cutoff
831 aMass = gMC->TrackMass();
832 if ((gMC->Etot() - aMass) > kEkinMinStep) {
833
834 // The energy loss according to Bethe Bloch
835 iPdg = TMath::Abs(gMC->TrackPid());
836 if ((iPdg != kPdgElectron) ||
837 ((iPdg == kPdgElectron) &&
838 (pTot < kPTotMaxEl))) {
839 gMC->TrackMomentum(mom);
840 pTot = mom.Rho();
841 betaGamma = pTot / aMass;
842 pp = kPrim * BetheBloch(betaGamma);
843 // Take charge > 1 into account
844 charge = gMC->TrackCharge();
845 if (TMath::Abs(charge) > 1) {
846 pp = pp * charge*charge;
f73816f5 847 }
ce0d6231 848 }
849 else {
850 // Electrons above 20 Mev/c are at the plateau
851 pp = kPrim * kPlateau;
852 }
f73816f5 853
ce0d6231 854 if (pp > 0.0) {
855 do {
856 gMC->GetRandom()->RndmArray(1,random);
030b4415 857 }
ce0d6231 858 while ((random[0] == 1.0) ||
859 (random[0] == 0.0));
860 stepSize = - TMath::Log(random[0]) / pp;
861 gMC->SetMaxStep(stepSize);
862 }
030b4415 863
5c7f4665 864 }
030b4415 865
d3f347ff 866 }
030b4415 867
5c7f4665 868 }
030b4415 869
5c7f4665 870}
871
872//_____________________________________________________________________________
a328fff9 873void AliTRDv1::StepManagerFixedStep()
874{
875 //
876 // Slow simulator. Every charged track produces electron cluster as hits
877 // along its path across the drift volume. The step size is fixed in
878 // this version of the step manager.
879 //
880
ce0d6231 881 // PDG code electron
882 const Int_t kPdgElectron = 11;
883
a328fff9 884 Int_t pla = 0;
885 Int_t cha = 0;
886 Int_t sec = 0;
887 Int_t det = 0;
888 Int_t qTot;
889
890 Float_t hits[3];
891 Double_t eDep;
892
893 Bool_t drRegion = kFALSE;
894 Bool_t amRegion = kFALSE;
895
2c8bf4aa 896 TString cIdPath;
897 Char_t cIdSector[3];
898 cIdSector[2] = 0;
899
a328fff9 900 TString cIdCurrent;
901 TString cIdSensDr = "J";
902 TString cIdSensAm = "K";
903 Char_t cIdChamber[3];
2c8bf4aa 904 cIdChamber[2] = 0;
a328fff9 905
030b4415 906 TLorentzVector pos;
907 TLorentzVector mom;
a328fff9 908
909 const Int_t kNplan = AliTRDgeometry::Nplan();
910 const Int_t kNcham = AliTRDgeometry::Ncham();
911 const Int_t kNdetsec = kNplan * kNcham;
912
030b4415 913 const Double_t kBig = 1.0e+12;
a328fff9 914
bc327ce2 915 const Float_t kWion = 23.53; // Ionization energy
a328fff9 916 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
917
918 // Set the maximum step size to a very large number for all
919 // neutral particles and those outside the driftvolume
920 gMC->SetMaxStep(kBig);
921
922 // If not charged track or already stopped or disappeared, just return.
923 if ((!gMC->TrackCharge()) ||
ce0d6231 924 gMC->IsTrackDisappeared()) {
925 return;
926 }
a328fff9 927
928 // Inside a sensitive volume?
929 cIdCurrent = gMC->CurrentVolName();
930
ce0d6231 931 if (cIdSensDr == cIdCurrent[1]) {
932 drRegion = kTRUE;
933 }
934 if (cIdSensAm == cIdCurrent[1]) {
935 amRegion = kTRUE;
936 }
a328fff9 937
030b4415 938 if ((!drRegion) &&
939 (!amRegion)) {
940 return;
941 }
a328fff9 942
943 // The hit coordinates and charge
944 gMC->TrackPosition(pos);
945 hits[0] = pos[0];
946 hits[1] = pos[1];
947 hits[2] = pos[2];
948
2c8bf4aa 949 // The sector number (0 - 17), according to standard coordinate system
950 cIdPath = gGeoManager->GetPath();
951 cIdSector[0] = cIdPath[21];
952 cIdSector[1] = cIdPath[22];
953 sec = atoi(cIdSector);
a328fff9 954
955 // The plane and chamber number
030b4415 956 cIdChamber[0] = cIdCurrent[2];
957 cIdChamber[1] = cIdCurrent[3];
a328fff9 958 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 959 cha = ((Int_t) idChamber / kNplan);
a328fff9 960 pla = ((Int_t) idChamber % kNplan);
e0d47c25 961
030b4415 962 // The detector number
963 det = fGeometry->GetDetector(pla,cha,sec);
964
25ca55ce 965 // 0: InFlight 1:Entering 2:Exiting
030b4415 966 Int_t trkStat = 0;
a328fff9 967
968 // Special hits only in the drift region
ce0d6231 969 if ((drRegion) &&
970 (gMC->IsTrackEntering())) {
a328fff9 971
ce0d6231 972 // Create a track reference at the entrance of each
973 // chamber that contains the momentum components of the particle
974 gMC->TrackMomentum(mom);
e6add757 975 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
ce0d6231 976 trkStat = 1;
a328fff9 977
ce0d6231 978 // Create the hits from TR photons if electron/positron is
979 // entering the drift volume
980 if ((fTR) &&
981 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
030b4415 982 CreateTRhit(det);
983 }
a328fff9 984
985 }
ce0d6231 986 else if ((amRegion) &&
987 (gMC->IsTrackExiting())) {
988
989 // Create a track reference at the exit of each
990 // chamber that contains the momentum components of the particle
991 gMC->TrackMomentum(mom);
e6add757 992 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
ce0d6231 993 trkStat = 2;
994
995 }
a328fff9 996
997 // Calculate the charge according to GEANT Edep
998 // Create a new dEdx hit
999 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1000 qTot = (Int_t) (eDep / kWion);
ce0d6231 1001 if ((qTot) ||
1002 (trkStat)) {
1003 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1004 ,det
1005 ,hits
1006 ,qTot
25ca55ce 1007 ,gMC->TrackTime()*1.0e06
ce0d6231 1008 ,drRegion);
1009 }
a328fff9 1010
1011 // Set Maximum Step Size
1012 // Produce only one hit if Ekin is below cutoff
030b4415 1013 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1014 return;
1015 }
a328fff9 1016 gMC->SetMaxStep(fStepSize);
1017
1018}
1019
1020//_____________________________________________________________________________
5c7f4665 1021Double_t AliTRDv1::BetheBloch(Double_t bg)
1022{
1023 //
1024 // Parametrization of the Bethe-Bloch-curve
1025 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1026 //
1027
1028 // This parameters have been adjusted to averaged values from GEANT
f57bb418 1029 const Double_t kP1 = 7.17960e-02;
1030 const Double_t kP2 = 8.54196;
1031 const Double_t kP3 = 1.38065e-06;
1032 const Double_t kP4 = 5.30972;
1033 const Double_t kP5 = 2.83798;
5c7f4665 1034
f73816f5 1035 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1036 const Double_t kBgMin = 0.8;
1037 const Double_t kBBMax = 6.83298;
f73816f5 1038
1039 if (bg > kBgMin) {
030b4415 1040 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
5c7f4665 1041 Double_t aa = TMath::Power(yy,kP4);
030b4415 1042 Double_t bb = TMath::Power((1.0/bg),kP5);
5c7f4665 1043 bb = TMath::Log(kP3 + bb);
030b4415 1044 return ((kP2 - aa - bb) * kP1 / aa);
5c7f4665 1045 }
f73816f5 1046 else {
1047 return kBBMax;
1048 }
d3f347ff 1049
fe4da5cc 1050}
5c7f4665 1051
1052//_____________________________________________________________________________
c4214bc0 1053Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
a328fff9 1054{
1055 //
1056 // Return dN/dx (number of primary collisions per centimeter)
1057 // for given beta*gamma factor.
1058 //
1059 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1060 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1061 // This must be used as a set with IntSpecGeant.
1062 //
1063
030b4415 1064 Int_t i = 0;
a328fff9 1065
030b4415 1066 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1067 , 1.800000, 2.000000, 2.500000, 3.000000
1068 , 4.000000, 7.000000, 10.000000, 20.000000
1069 , 40.000000, 70.000000, 100.000000, 300.000000
1070 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
a328fff9 1071
030b4415 1072 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1073 , 22.734999, 21.411915, 19.934095, 19.449375
1074 , 19.344431, 20.185553, 21.027925, 22.912676
1075 , 24.933352, 26.504053, 27.387468, 29.566597
1076 , 30.353779, 30.787134, 31.129285, 31.157350 };
1077
1078 // Betagamma to gamma
1079 Double_t g = TMath::Sqrt(1.0 + bg*bg);
a328fff9 1080
1081 // Find the index just before the point we need.
030b4415 1082 for (i = 0; i < 18; i++) {
1083 if ((arrG[i] < g) &&
1084 (arrG[i+1] > g)) {
a328fff9 1085 break;
030b4415 1086 }
1087 }
a328fff9 1088
1089 // Simple interpolation.
030b4415 1090 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1091 * (g - arrG[i]) + arrNC[i];
a328fff9 1092
030b4415 1093 return pp;
a328fff9 1094
1095}
1096
1097//_____________________________________________________________________________
5c7f4665 1098Double_t Ermilova(Double_t *x, Double_t *)
1099{
1100 //
1101 // Calculates the delta-ray energy distribution according to Ermilova.
1102 // Logarithmic scale !
1103 //
1104
1105 Double_t energy;
1106 Double_t dpos;
1107 Double_t dnde;
1108
030b4415 1109 Int_t pos1;
1110 Int_t pos2;
5c7f4665 1111
8230f242 1112 const Int_t kNv = 31;
5c7f4665 1113
030b4415 1114 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1115 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1116 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1117 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1118 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1119 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1120 , 11.5129 };
1121
1122 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1123 , 20.9, 20.8, 20.0, 16.0, 11.0
1124 , 8.0, 6.0, 5.2, 4.6, 4.0
1125 , 3.5, 3.0, 1.4, 0.67, 0.44
1126 , 0.3, 0.18, 0.12, 0.08, 0.056
1127 , 0.04, 0.023, 0.015, 0.011, 0.01
1128 , 0.004 };
5c7f4665 1129
1130 energy = x[0];
1131
1132 // Find the position
030b4415 1133 pos1 = 0;
1134 pos2 = 0;
5c7f4665 1135 dpos = 0;
1136 do {
1137 dpos = energy - vxe[pos2++];
1138 }
1139 while (dpos > 0);
1140 pos2--;
030b4415 1141 if (pos2 > kNv) {
1142 pos2 = kNv - 1;
1143 }
5c7f4665 1144 pos1 = pos2 - 1;
1145
1146 // Differentiate between the sampling points
1147 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1148
1149 return dnde;
1150
1151}
a328fff9 1152
1153//_____________________________________________________________________________
1154Double_t IntSpecGeant(Double_t *x, Double_t *)
1155{
1156 //
1157 // Integrated spectrum from Geant3
1158 //
1159
96efaf83 1160 const Int_t npts = 83;
030b4415 1161 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1162 , 2.672067, 2.813299, 3.015059, 3.216819
1163 , 3.418579, 3.620338, 3.868209, 3.920198
1164 , 3.978284, 4.063923, 4.186264, 4.308605
1165 , 4.430946, 4.553288, 4.724261, 4.837736
1166 , 4.999842, 5.161949, 5.324056, 5.486163
1167 , 5.679688, 5.752998, 5.857728, 5.962457
1168 , 6.067185, 6.171914, 6.315653, 6.393674
1169 , 6.471694, 6.539689, 6.597658, 6.655627
1170 , 6.710957, 6.763648, 6.816338, 6.876198
1171 , 6.943227, 7.010257, 7.106285, 7.252151
1172 , 7.460531, 7.668911, 7.877290, 8.085670
1173 , 8.302979, 8.353585, 8.413120, 8.483500
1174 , 8.541030, 8.592857, 8.668865, 8.820485
1175 , 9.037086, 9.253686, 9.470286, 9.686887
1176 , 9.930838, 9.994655, 10.085822, 10.176990
1177 , 10.268158, 10.359325, 10.503614, 10.627565
1178 , 10.804637, 10.981709, 11.158781, 11.335854
1179 , 11.593397, 11.781165, 12.049404, 12.317644
1180 , 12.585884, 12.854123, 14.278421, 16.975889
1181 , 20.829416, 24.682943, 28.536469 };
1182
1183 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1184 , 9.1601500, 8.206670, 6.919630, 5.655430
1185 , 4.6221300, 3.777610, 3.019560, 2.591950
1186 , 2.5414600, 2.712920, 3.327460, 4.928240
1187 , 7.6185300, 10.966700, 12.225800, 8.094750
1188 , 3.3586900, 1.553650, 1.209600, 1.263840
1189 , 1.3241100, 1.312140, 1.255130, 1.165770
1190 , 1.0594500, 0.945450, 0.813231, 0.699837
1191 , 0.6235580, 2.260990, 2.968350, 2.240320
1192 , 1.7988300, 1.553300, 1.432070, 1.535520
1193 , 1.4429900, 1.247990, 1.050750, 0.829549
1194 , 0.5900280, 0.395897, 0.268741, 0.185320
1195 , 0.1292120, 0.103545, 0.0949525, 0.101535
1196 , 0.1276380, 0.134216, 0.123816, 0.104557
1197 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1198 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1199 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1200 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1201 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1202 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1203 , 3.63304e-06, 0.0000000, 0.0000000 };
1204
1205 Int_t i;
a328fff9 1206 Double_t energy = x[0];
a328fff9 1207
225211c8 1208 if (energy >= arre[npts-1]) {
1209 return 0.0;
1210 }
1211
030b4415 1212 for (i = 0; i < npts; i++) {
1213 if (energy < arre[i]) {
1214 break;
1215 }
1216 }
a328fff9 1217
030b4415 1218 if (i == 0) {
1219 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");
1220 }
a328fff9 1221
f57bb418 1222 return arrdnde[i];
a328fff9 1223
1224}