Coding rule violations corrected (A. de Falco)
[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>
fe4da5cc 32
d3f347ff 33#include "AliConst.h"
45160b1f 34#include "AliLog.h"
35#include "AliMC.h"
88cb7938 36#include "AliRun.h"
030b4415 37
88cb7938 38#include "AliTRDgeometry.h"
793ff80c 39#include "AliTRDhit.h"
793ff80c 40#include "AliTRDsim.h"
88cb7938 41#include "AliTRDv1.h"
851d3db9 42
fe4da5cc 43ClassImp(AliTRDv1)
8230f242 44
45//_____________________________________________________________________________
030b4415 46AliTRDv1::AliTRDv1()
47 :AliTRD()
48 ,fTRon(kFALSE)
49 ,fTR(NULL)
50 ,fTypeOfStepManager(0)
51 ,fStepSize(0)
52 ,fDeltaE(NULL)
53 ,fDeltaG(NULL)
54 ,fTrackLength0(0)
55 ,fPrimaryTrackPid(0)
8230f242 56{
57 //
58 // Default constructor
59 //
60
8230f242 61}
62
fe4da5cc 63//_____________________________________________________________________________
64AliTRDv1::AliTRDv1(const char *name, const char *title)
030b4415 65 :AliTRD(name,title)
66 ,fTRon(kTRUE)
67 ,fTR(NULL)
68 ,fTypeOfStepManager(1)
69 ,fStepSize(0.1)
70 ,fDeltaE(NULL)
71 ,fDeltaG(NULL)
72 ,fTrackLength0(0)
73 ,fPrimaryTrackPid(0)
fe4da5cc 74{
75 //
851d3db9 76 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 77 //
82bbf98a 78
5c7f4665 79 SetBufferSize(128000);
80
81}
82
83//_____________________________________________________________________________
030b4415 84AliTRDv1::AliTRDv1(const AliTRDv1 &trd)
85 :AliTRD(trd)
86 ,fTRon(trd.fTRon)
87 ,fTR(NULL)
88 ,fTypeOfStepManager(trd.fTypeOfStepManager)
89 ,fStepSize(trd.fStepSize)
90 ,fDeltaE(NULL)
91 ,fDeltaG(NULL)
92 ,fTrackLength0(trd.fTrackLength0)
93 ,fPrimaryTrackPid(trd.fPrimaryTrackPid)
8230f242 94{
95 //
96 // Copy constructor
97 //
98
030b4415 99 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
100 fDeltaG->Copy(*((AliTRDv1 &) trd).fDeltaG);
101 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 102
103}
104
105//_____________________________________________________________________________
5c7f4665 106AliTRDv1::~AliTRDv1()
107{
dd9a6ee3 108 //
109 // AliTRDv1 destructor
110 //
82bbf98a 111
030b4415 112 if (fDeltaE) {
113 delete fDeltaE;
114 fDeltaE = 0;
115 }
116
117 if (fDeltaG) {
118 delete fDeltaG;
119 fDeltaG = 0;
120 }
121
122 if (fTR) {
123 delete fTR;
124 fTR = 0;
125 }
82bbf98a 126
fe4da5cc 127}
128
dd9a6ee3 129//_____________________________________________________________________________
130AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
131{
132 //
133 // Assignment operator
134 //
135
136 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
030b4415 137
dd9a6ee3 138 return *this;
139
140}
8230f242 141
142//_____________________________________________________________________________
e0d47c25 143void AliTRDv1::Copy(TObject &trd) const
8230f242 144{
145 //
146 // Copy function
147 //
148
a328fff9 149 ((AliTRDv1 &) trd).fTypeOfStepManager = fTypeOfStepManager;
150 ((AliTRDv1 &) trd).fStepSize = fStepSize;
bd0f8685 151 ((AliTRDv1 &) trd).fTRon = fTRon;
030b4415 152 ((AliTRDv1 &) trd).fTrackLength0 = fTrackLength0;
153 ((AliTRDv1 &) trd).fPrimaryTrackPid = fPrimaryTrackPid;
bd0f8685 154
793ff80c 155 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
a328fff9 156 fDeltaG->Copy(*((AliTRDv1 &) trd).fDeltaG);
793ff80c 157 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 158
159}
160
fe4da5cc 161//_____________________________________________________________________________
162void AliTRDv1::CreateGeometry()
163{
164 //
851d3db9 165 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 166 // This version covers the full azimuth.
d3f347ff 167 //
168
82bbf98a 169 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 170 AliModule* frame = gAlice->GetModule("FRAME");
030b4415 171 if (!frame) {
172 AliError("TRD needs FRAME to be present\n");
173 return;
174 }
d3f347ff 175
82bbf98a 176 // Define the chambers
177 AliTRD::CreateGeometry();
d3f347ff 178
fe4da5cc 179}
180
181//_____________________________________________________________________________
182void AliTRDv1::CreateMaterials()
183{
184 //
851d3db9 185 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 186 //
82bbf98a 187
d3f347ff 188 AliTRD::CreateMaterials();
82bbf98a 189
fe4da5cc 190}
191
192//_____________________________________________________________________________
793ff80c 193void AliTRDv1::CreateTRhit(Int_t det)
194{
195 //
196 // Creates an electron cluster from a TR photon.
197 // The photon is assumed to be created a the end of the radiator. The
198 // distance after which it deposits its energy takes into account the
199 // absorbtion of the entrance window and of the gas mixture in drift
200 // volume.
201 //
202
203 // PDG code electron
204 const Int_t kPdgElectron = 11;
205
206 // Ionization energy
bc327ce2 207 const Float_t kWion = 23.53;
793ff80c 208
209 // Maximum number of TR photons per track
210 const Int_t kNTR = 50;
211
030b4415 212 TLorentzVector mom;
213 TLorentzVector pos;
793ff80c 214
793ff80c 215 // Create TR at the entrance of the chamber
216 if (gMC->IsTrackEntering()) {
217
f73816f5 218 // Create TR only for electrons
219 Int_t iPdg = gMC->TrackPid();
030b4415 220 if (TMath::Abs(iPdg) != kPdgElectron) {
221 return;
222 }
f73816f5 223
793ff80c 224 Float_t eTR[kNTR];
225 Int_t nTR;
226
227 // Create TR photons
228 gMC->TrackMomentum(mom);
229 Float_t pTot = mom.Rho();
230 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
231 if (nTR > kNTR) {
45160b1f 232 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
793ff80c 233 }
234
235 // Loop through the TR photons
236 for (Int_t iTR = 0; iTR < nTR; iTR++) {
237
238 Float_t energyMeV = eTR[iTR] * 0.001;
239 Float_t energyeV = eTR[iTR] * 1000.0;
030b4415 240 Float_t absLength = 0.0;
241 Float_t sigma = 0.0;
793ff80c 242
243 // Take the absorbtion in the entrance window into account
244 Double_t muMy = fTR->GetMuMy(energyMeV);
030b4415 245 sigma = muMy * fFoilDensity;
842287f2 246 if (sigma > 0.0) {
247 absLength = gRandom->Exp(1.0/sigma);
030b4415 248 if (absLength < AliTRDgeometry::MyThick()) {
249 continue;
250 }
842287f2 251 }
252 else {
253 continue;
254 }
793ff80c 255
256 // The absorbtion cross sections in the drift gas
3dac2b2d 257 // Gas-mixture (Xe/CO2)
258 Double_t muXe = fTR->GetMuXe(energyMeV);
259 Double_t muCO = fTR->GetMuCO(energyMeV);
260 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
793ff80c 261
262 // The distance after which the energy of the TR photon
263 // is deposited.
842287f2 264 if (sigma > 0.0) {
265 absLength = gRandom->Exp(1.0/sigma);
a328fff9 266 if (absLength > (AliTRDgeometry::DrThick()
267 + AliTRDgeometry::AmThick())) {
268 continue;
269 }
842287f2 270 }
271 else {
272 continue;
273 }
793ff80c 274
275 // The position of the absorbtion
276 Float_t posHit[3];
277 gMC->TrackPosition(pos);
278 posHit[0] = pos[0] + mom[0] / pTot * absLength;
279 posHit[1] = pos[1] + mom[1] / pTot * absLength;
c4214bc0 280 posHit[2] = pos[2] + mom[2] / pTot * absLength;
793ff80c 281
282 // Create the charge
283 Int_t q = ((Int_t) (energyeV / kWion));
284
285 // Add the hit to the array. TR photon hits are marked
286 // by negative charge
030b4415 287 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
288 ,det
289 ,posHit
290 ,-q
291 ,kTRUE);
793ff80c 292
293 }
294
295 }
296
297}
298
299//_____________________________________________________________________________
5c7f4665 300void AliTRDv1::Init()
301{
302 //
303 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 304 //
305
306 AliTRD::Init();
307
45160b1f 308 AliDebug(1,"Slow simulator\n");
bd0f8685 309
310 // Switch on TR simulation as default
311 if (!fTRon) {
45160b1f 312 AliInfo("TR simulation off");
bd0f8685 313 }
314 else {
315 fTR = new AliTRDsim();
316 }
5c7f4665 317
318 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
319 const Float_t kPoti = 12.1;
320 // Maximum energy (50 keV);
321 const Float_t kEend = 50000.0;
322 // Ermilova distribution for the delta-ray spectrum
030b4415 323 Float_t poti = TMath::Log(kPoti);
324 Float_t eEnd = TMath::Log(kEend);
a328fff9 325
326 // Ermilova distribution for the delta-ray spectrum
c4214bc0 327 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
a328fff9 328
329 // Geant3 distribution for the delta-ray spectrum
c4214bc0 330 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
5c7f4665 331
45160b1f 332 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
5c7f4665 333
fe4da5cc 334}
335
336//_____________________________________________________________________________
5c7f4665 337void AliTRDv1::StepManager()
338{
339 //
c4214bc0 340 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 341 // along its path across the drift volume.
342 //
343
344 switch (fTypeOfStepManager) {
345 case 0 : StepManagerErmilova(); break; // 0 is Ermilova
346 case 1 : StepManagerGeant(); break; // 1 is Geant
347 case 2 : StepManagerFixedStep(); break; // 2 is fixed step
45160b1f 348 default : AliWarning("Not a valid Step Manager.");
a328fff9 349 }
350
351}
352
353//_____________________________________________________________________________
354void AliTRDv1::SelectStepManager(Int_t t)
355{
356 //
357 // Selects a step manager type:
358 // 0 - Ermilova
359 // 1 - Geant3
360 // 2 - Fixed step size
361 //
362
a328fff9 363 fTypeOfStepManager = t;
45160b1f 364 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
a328fff9 365
366}
367
368//_____________________________________________________________________________
369void AliTRDv1::StepManagerGeant()
370{
371 //
c4214bc0 372 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 373 // along its path across the drift volume. The step size is set acording
374 // to Bethe-Bloch. The energy distribution of the delta electrons follows
375 // a spectrum taken from Geant3.
376 //
f2e3a0b5 377 // Version by A. Bercuci
378 //
379
c4214bc0 380 Int_t pla = 0;
381 Int_t cha = 0;
382 Int_t sec = 0;
383 Int_t det = 0;
384 Int_t iPdg;
385 Int_t qTot;
386
387 Float_t hits[3];
388 Float_t charge;
389 Float_t aMass;
390
030b4415 391 Double_t pTot = 0;
c4214bc0 392 Double_t eDelta;
030b4415 393 Double_t betaGamma;
394 Double_t pp;
f2e3a0b5 395 Double_t stepSize = 0;
c4214bc0 396
397 Bool_t drRegion = kFALSE;
398 Bool_t amRegion = kFALSE;
399
400 TString cIdCurrent;
401 TString cIdSensDr = "J";
402 TString cIdSensAm = "K";
403 Char_t cIdChamber[3];
404 cIdChamber[2] = 0;
405
030b4415 406 TLorentzVector pos;
407 TLorentzVector mom;
c4214bc0 408
030b4415 409 TArrayI processes;
f2e3a0b5 410
c4214bc0 411 const Int_t kNplan = AliTRDgeometry::Nplan();
412 const Int_t kNcham = AliTRDgeometry::Ncham();
413 const Int_t kNdetsec = kNplan * kNcham;
414
030b4415 415 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 416 const Float_t kWion = 23.53; // Ionization energy
c4214bc0 417 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
418
419 // Minimum energy for the step size adjustment
420 const Float_t kEkinMinStep = 1.0e-5;
421 // energy threshold for production of delta electrons
f2e3a0b5 422 const Float_t kECut = 1.0e4;
423 // Parameters entering the parametrized range for delta electrons
030b4415 424 const Float_t kRa = 5.37e-4;
f2e3a0b5 425 const Float_t kRb = 0.9815;
030b4415 426 const Float_t kRc = 3.123e-3;
f2e3a0b5 427 // Gas density -> To be made user adjustable !
030b4415 428 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
429 const Float_t kRho = 0.004945 ;
a328fff9 430
c4214bc0 431 // Plateau value of the energy-loss for electron in xenon
030b4415 432 // The averaged value (26/3/99)
c4214bc0 433 const Float_t kPlateau = 1.55;
030b4415 434 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
435 const Float_t kPrim = 19.34;
c4214bc0 436 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
437 const Float_t kPoti = 12.1;
030b4415 438 // PDG code electron
439 const Int_t kPdgElectron = 11;
c4214bc0 440
441 // Set the maximum step size to a very large number for all
442 // neutral particles and those outside the driftvolume
443 gMC->SetMaxStep(kBig);
444
445 // Use only charged tracks
446 if (( gMC->TrackCharge() ) &&
c4214bc0 447 (!gMC->IsTrackDisappeared())) {
448
449 // Inside a sensitive volume?
450 drRegion = kFALSE;
451 amRegion = kFALSE;
452 cIdCurrent = gMC->CurrentVolName();
453 if (cIdSensDr == cIdCurrent[1]) {
454 drRegion = kTRUE;
455 }
456 if (cIdSensAm == cIdCurrent[1]) {
457 amRegion = kTRUE;
458 }
459 if (drRegion || amRegion) {
a328fff9 460
c4214bc0 461 // The hit coordinates and charge
462 gMC->TrackPosition(pos);
463 hits[0] = pos[0];
464 hits[1] = pos[1];
465 hits[2] = pos[2];
466
467 // The sector number (0 - 17)
468 // The numbering goes clockwise and starts at y = 0
469 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
030b4415 470 if (phi < 90.0) {
471 phi = phi + 270.0;
472 }
473 else {
474 phi = phi - 90.0;
475 }
476 sec = ((Int_t) (phi / 20.0));
c4214bc0 477
478 // The plane and chamber number
030b4415 479 cIdChamber[0] = cIdCurrent[2];
480 cIdChamber[1] = cIdCurrent[3];
c4214bc0 481 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
482 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
483 pla = ((Int_t) idChamber % kNplan);
484
485 // Check on selected volumes
486 Int_t addthishit = 1;
c4214bc0 487
488 // Add this hit
489 if (addthishit) {
490
491 // The detector number
492 det = fGeometry->GetDetector(pla,cha,sec);
493
494 // Special hits only in the drift region
495 if (drRegion) {
f2e3a0b5 496
c4214bc0 497 // Create a track reference at the entrance and
498 // exit of each chamber that contain the
f2e3a0b5 499 // momentum components of the particle
030b4415 500 if (gMC->IsTrackEntering() ||
501 gMC->IsTrackExiting()) {
c4214bc0 502 gMC->TrackMomentum(mom);
503 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
504 }
f2e3a0b5 505
030b4415 506 if (gMC->IsTrackEntering() &&
507 !gMC->IsNewTrack()) {
f2e3a0b5 508 // determine if hit belong to primary track
509 fPrimaryTrackPid = gAlice->GetMCApp()->GetCurrentTrackNumber();
510 // determine track length when entering the detector
511 fTrackLength0 = gMC->TrackLength();
512 }
c4214bc0 513
f2e3a0b5 514 // Create the hits from TR photons
c4214bc0 515 if (fTR) CreateTRhit(det);
c4214bc0 516
f2e3a0b5 517 }
c4214bc0 518
f2e3a0b5 519 // Calculate the energy of the delta-electrons
520 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
521 // take into account correlation with the underlying GEANT tracking
522 // mechanism. see
523 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
524 //
525 // determine the most significant process (last on the processes list)
526 // which caused this hit
c4214bc0 527 gMC->StepProcesses(processes);
f2e3a0b5 528 Int_t nofprocesses = processes.GetSize();
529 Int_t pid;
530 if (!nofprocesses) {
531 pid = 0;
532 }
533 else {
534 pid = processes[nofprocesses-1];
535 }
536
537 // generate Edep according to GEANT parametrisation
538 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
539 eDelta = TMath::Max(eDelta,0.0);
030b4415 540 Float_t prRange = 0.0;
541 Float_t range = gMC->TrackLength() - fTrackLength0;
f2e3a0b5 542 // merge GEANT tracker information with locally cooked one
543 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
f2e3a0b5 544 if (pid == 27) {
545 if (eDelta >= kECut) {
030b4415 546 prRange = kRa * eDelta * 0.001
547 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
548 if (prRange >= (3.7 - range)) {
549 eDelta *= 0.1;
550 }
f2e3a0b5 551 }
552 }
553 else if (pid == 1) {
554 if (eDelta < kECut) {
555 eDelta *= 0.5;
556 }
557 else {
030b4415 558 prRange = kRa * eDelta * 0.001
559 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
560 if (prRange >= ((AliTRDgeometry::DrThick()
561 + AliTRDgeometry::AmThick()) - range)) {
f2e3a0b5 562 eDelta *= 0.05;
563 }
564 else {
565 eDelta *= 0.5;
566 }
567 }
568 }
569 else {
570 eDelta = 0.0;
571 }
572 }
573 else {
574 eDelta = 0.0;
575 }
c4214bc0 576
577 // Generate the electron cluster size
f2e3a0b5 578 if (eDelta == 0.0) {
579 qTot = 0;
580 }
581 else {
582 qTot = ((Int_t) (eDelta / kWion) + 1);
583 }
584
585 // Create a new dEdx hit
030b4415 586 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
587 ,det
588 ,hits
589 ,qTot
590 ,drRegion);
c4214bc0 591
592 // Calculate the maximum step size for the next tracking step
593 // Produce only one hit if Ekin is below cutoff
594 aMass = gMC->TrackMass();
595 if ((gMC->Etot() - aMass) > kEkinMinStep) {
596
597 // The energy loss according to Bethe Bloch
f2e3a0b5 598 iPdg = TMath::Abs(gMC->TrackPid());
599 if ((iPdg != kPdgElectron) ||
030b4415 600 ((iPdg == kPdgElectron) &&
601 (pTot < kPTotMaxEl))) {
c4214bc0 602 gMC->TrackMomentum(mom);
603 pTot = mom.Rho();
604 betaGamma = pTot / aMass;
605 pp = BetheBlochGeant(betaGamma);
f2e3a0b5 606 // Take charge > 1 into account
030b4415 607 charge = gMC->TrackCharge();
f2e3a0b5 608 if (TMath::Abs(charge) > 1) {
609 pp = pp * charge*charge;
610 }
611 }
612 else {
613 // Electrons above 20 Mev/c are at the plateau
614 pp = kPrim * kPlateau;
c4214bc0 615 }
616
1b775a44 617 Int_t nsteps = 0;
030b4415 618 do {
619 nsteps = gRandom->Poisson(pp);
620 } while(!nsteps);
621 stepSize = 1.0 / nsteps;
1b775a44 622 gMC->SetMaxStep(stepSize);
f2e3a0b5 623
1b775a44 624 }
f2e3a0b5 625
c4214bc0 626 }
f2e3a0b5 627
c4214bc0 628 }
f2e3a0b5 629
c4214bc0 630 }
f2e3a0b5 631
a328fff9 632}
633
634//_____________________________________________________________________________
635void AliTRDv1::StepManagerErmilova()
636{
637 //
638 // Slow simulator. Every charged track produces electron cluster as hits
5c7f4665 639 // along its path across the drift volume. The step size is set acording
640 // to Bethe-Bloch. The energy distribution of the delta electrons follows
641 // a spectrum taken from Ermilova et al.
642 //
643
851d3db9 644 Int_t pla = 0;
645 Int_t cha = 0;
646 Int_t sec = 0;
793ff80c 647 Int_t det = 0;
851d3db9 648 Int_t iPdg;
793ff80c 649 Int_t qTot;
5c7f4665 650
793ff80c 651 Float_t hits[3];
a5cadd36 652 Double_t random[1];
5c7f4665 653 Float_t charge;
654 Float_t aMass;
655
030b4415 656 Double_t pTot = 0.0;
5c7f4665 657 Double_t eDelta;
030b4415 658 Double_t betaGamma;
659 Double_t pp;
f73816f5 660 Double_t stepSize;
5c7f4665 661
332e9569 662 Bool_t drRegion = kFALSE;
663 Bool_t amRegion = kFALSE;
664
665 TString cIdCurrent;
666 TString cIdSensDr = "J";
667 TString cIdSensAm = "K";
593a9fc3 668 Char_t cIdChamber[3];
669 cIdChamber[2] = 0;
332e9569 670
030b4415 671 TLorentzVector pos;
672 TLorentzVector mom;
82bbf98a 673
332e9569 674 const Int_t kNplan = AliTRDgeometry::Nplan();
e644678a 675 const Int_t kNcham = AliTRDgeometry::Ncham();
676 const Int_t kNdetsec = kNplan * kNcham;
677
030b4415 678 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 679 const Float_t kWion = 23.53; // Ionization energy
a328fff9 680 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
5c7f4665 681
f73816f5 682 // Minimum energy for the step size adjustment
683 const Float_t kEkinMinStep = 1.0e-5;
a328fff9 684
5c7f4665 685 // Plateau value of the energy-loss for electron in xenon
030b4415 686 // The averaged value (26/3/99)
a3c76cdc 687 const Float_t kPlateau = 1.55;
030b4415 688 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
689 const Float_t kPrim = 48.0;
5c7f4665 690 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 691 const Float_t kPoti = 12.1;
030b4415 692 // PDG code electron
693 const Int_t kPdgElectron = 11;
5c7f4665 694
695 // Set the maximum step size to a very large number for all
696 // neutral particles and those outside the driftvolume
697 gMC->SetMaxStep(kBig);
698
699 // Use only charged tracks
700 if (( gMC->TrackCharge() ) &&
5c7f4665 701 (!gMC->IsTrackDisappeared())) {
fe4da5cc 702
5c7f4665 703 // Inside a sensitive volume?
332e9569 704 drRegion = kFALSE;
705 amRegion = kFALSE;
706 cIdCurrent = gMC->CurrentVolName();
e6674585 707 if (cIdSensDr == cIdCurrent[1]) {
332e9569 708 drRegion = kTRUE;
709 }
e6674585 710 if (cIdSensAm == cIdCurrent[1]) {
332e9569 711 amRegion = kTRUE;
712 }
713 if (drRegion || amRegion) {
fe4da5cc 714
5c7f4665 715 // The hit coordinates and charge
716 gMC->TrackPosition(pos);
717 hits[0] = pos[0];
718 hits[1] = pos[1];
719 hits[2] = pos[2];
5c7f4665 720
851d3db9 721 // The sector number (0 - 17)
722 // The numbering goes clockwise and starts at y = 0
e15eb584 723 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
030b4415 724 if (phi < 90.0) {
725 phi = phi + 270.0;
726 }
727 else {
728 phi = phi - 90.0;
729 }
730 sec = ((Int_t) (phi / 20.0));
82bbf98a 731
332e9569 732 // The plane and chamber number
733 cIdChamber[0] = cIdCurrent[2];
734 cIdChamber[1] = cIdCurrent[3];
e644678a 735 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
a5cadd36 736 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
332e9569 737 pla = ((Int_t) idChamber % kNplan);
82bbf98a 738
5c7f4665 739 // Check on selected volumes
740 Int_t addthishit = 1;
5c7f4665 741
742 // Add this hit
743 if (addthishit) {
744
f73816f5 745 // The detector number
793ff80c 746 det = fGeometry->GetDetector(pla,cha,sec);
747
a328fff9 748 // Special hits only in the drift region
332e9569 749 if (drRegion) {
f73816f5 750
c61f1a66 751 // Create a track reference at the entrance and
752 // exit of each chamber that contain the
753 // momentum components of the particle
030b4415 754 if (gMC->IsTrackEntering() ||
755 gMC->IsTrackExiting()) {
f73816f5 756 gMC->TrackMomentum(mom);
5d12ce38 757 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
f73816f5 758 }
f73816f5 759 // Create the hits from TR photons
030b4415 760 if (fTR) {
761 CreateTRhit(det);
762 }
f73816f5 763
030b4415 764 }
f73816f5 765
766 // Calculate the energy of the delta-electrons
767 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
768 eDelta = TMath::Max(eDelta,0.0);
c4214bc0 769 // Generate the electron cluster size
030b4415 770 if (eDelta == 0.0) {
771 qTot = 0;
772 }
773 else {
774 qTot = ((Int_t) (eDelta / kWion) + 1);
775 }
f73816f5 776
030b4415 777 // Create a new dEdx hit
332e9569 778 if (drRegion) {
a328fff9 779 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 780 ,det
781 ,hits
782 ,qTot
783 ,kTRUE);
784 }
5c7f4665 785 else {
a328fff9 786 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 787 ,det
788 ,hits
789 ,qTot
790 ,kFALSE);
791 }
f73816f5 792
5c7f4665 793 // Calculate the maximum step size for the next tracking step
f73816f5 794 // Produce only one hit if Ekin is below cutoff
795 aMass = gMC->TrackMass();
796 if ((gMC->Etot() - aMass) > kEkinMinStep) {
797
798 // The energy loss according to Bethe Bloch
799 iPdg = TMath::Abs(gMC->TrackPid());
030b4415 800 if ((iPdg != kPdgElectron) ||
801 ((iPdg == kPdgElectron) &&
802 (pTot < kPTotMaxEl))) {
f73816f5 803 gMC->TrackMomentum(mom);
804 pTot = mom.Rho();
805 betaGamma = pTot / aMass;
806 pp = kPrim * BetheBloch(betaGamma);
807 // Take charge > 1 into account
808 charge = gMC->TrackCharge();
030b4415 809 if (TMath::Abs(charge) > 1) {
810 pp = pp * charge*charge;
811 }
812 }
813 else {
814 // Electrons above 20 Mev/c are at the plateau
815 pp = kPrim * kPlateau;
f73816f5 816 }
817
030b4415 818 if (pp > 0.0) {
819 do {
820 gMC->GetRandom()->RndmArray(1,random);
821 }
822 while ((random[0] == 1.0) ||
823 (random[0] == 0.0));
f73816f5 824 stepSize = - TMath::Log(random[0]) / pp;
825 gMC->SetMaxStep(stepSize);
030b4415 826 }
827
828 }
829
5c7f4665 830 }
030b4415 831
d3f347ff 832 }
030b4415 833
5c7f4665 834 }
030b4415 835
5c7f4665 836}
837
838//_____________________________________________________________________________
a328fff9 839void AliTRDv1::StepManagerFixedStep()
840{
841 //
842 // Slow simulator. Every charged track produces electron cluster as hits
843 // along its path across the drift volume. The step size is fixed in
844 // this version of the step manager.
845 //
846
847 Int_t pla = 0;
848 Int_t cha = 0;
849 Int_t sec = 0;
850 Int_t det = 0;
851 Int_t qTot;
852
853 Float_t hits[3];
854 Double_t eDep;
855
856 Bool_t drRegion = kFALSE;
857 Bool_t amRegion = kFALSE;
858
859 TString cIdCurrent;
860 TString cIdSensDr = "J";
861 TString cIdSensAm = "K";
862 Char_t cIdChamber[3];
863 cIdChamber[2] = 0;
864
030b4415 865 TLorentzVector pos;
866 TLorentzVector mom;
a328fff9 867
868 const Int_t kNplan = AliTRDgeometry::Nplan();
869 const Int_t kNcham = AliTRDgeometry::Ncham();
870 const Int_t kNdetsec = kNplan * kNcham;
871
030b4415 872 const Double_t kBig = 1.0e+12;
a328fff9 873
bc327ce2 874 const Float_t kWion = 23.53; // Ionization energy
a328fff9 875 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
876
877 // Set the maximum step size to a very large number for all
878 // neutral particles and those outside the driftvolume
879 gMC->SetMaxStep(kBig);
880
881 // If not charged track or already stopped or disappeared, just return.
882 if ((!gMC->TrackCharge()) ||
a328fff9 883 gMC->IsTrackDisappeared()) return;
884
885 // Inside a sensitive volume?
886 cIdCurrent = gMC->CurrentVolName();
887
888 if (cIdSensDr == cIdCurrent[1]) drRegion = kTRUE;
889 if (cIdSensAm == cIdCurrent[1]) amRegion = kTRUE;
890
030b4415 891 if ((!drRegion) &&
892 (!amRegion)) {
893 return;
894 }
a328fff9 895
896 // The hit coordinates and charge
897 gMC->TrackPosition(pos);
898 hits[0] = pos[0];
899 hits[1] = pos[1];
900 hits[2] = pos[2];
901
902 // The sector number (0 - 17)
903 // The numbering goes clockwise and starts at y = 0
904 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
030b4415 905 if (phi < 90.0) {
906 phi = phi + 270.0;
907 }
908 else {
909 phi = phi - 90.0;
910 }
911 sec = ((Int_t) (phi / 20.0));
a328fff9 912
913 // The plane and chamber number
030b4415 914 cIdChamber[0] = cIdCurrent[2];
915 cIdChamber[1] = cIdCurrent[3];
a328fff9 916 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
a5cadd36 917 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
a328fff9 918 pla = ((Int_t) idChamber % kNplan);
e0d47c25 919
a328fff9 920 // Check on selected volumes
921 Int_t addthishit = 1;
a328fff9 922
030b4415 923 if (!addthishit) {
924 return;
925 }
a328fff9 926
030b4415 927 // The detector number
928 det = fGeometry->GetDetector(pla,cha,sec);
929
930 // 0: InFlight 1:Entering 2:Exiting
931 Int_t trkStat = 0;
a328fff9 932
933 // Special hits only in the drift region
934 if (drRegion) {
935
936 // Create a track reference at the entrance and exit of each
937 // chamber that contain the momentum components of the particle
938
939 if (gMC->IsTrackEntering()) {
940 gMC->TrackMomentum(mom);
941 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
942 trkStat = 1;
943 }
944 if (gMC->IsTrackExiting()) {
945 gMC->TrackMomentum(mom);
946 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
947 trkStat = 2;
948 }
949
950 // Create the hits from TR photons
030b4415 951 if (fTR) {
952 CreateTRhit(det);
953 }
a328fff9 954
955 }
956
957 // Calculate the charge according to GEANT Edep
958 // Create a new dEdx hit
959 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
960 qTot = (Int_t) (eDep / kWion);
c4214bc0 961 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 962 ,det
963 ,hits
964 ,qTot
965 ,drRegion);
a328fff9 966
967 // Set Maximum Step Size
968 // Produce only one hit if Ekin is below cutoff
030b4415 969 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
970 return;
971 }
a328fff9 972 gMC->SetMaxStep(fStepSize);
973
974}
975
976//_____________________________________________________________________________
5c7f4665 977Double_t AliTRDv1::BetheBloch(Double_t bg)
978{
979 //
980 // Parametrization of the Bethe-Bloch-curve
981 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
982 //
983
984 // This parameters have been adjusted to averaged values from GEANT
985 const Double_t kP1 = 7.17960e-02;
986 const Double_t kP2 = 8.54196;
987 const Double_t kP3 = 1.38065e-06;
988 const Double_t kP4 = 5.30972;
989 const Double_t kP5 = 2.83798;
990
f73816f5 991 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
992 const Double_t kBgMin = 0.8;
993 const Double_t kBBMax = 6.83298;
f73816f5 994
995 if (bg > kBgMin) {
030b4415 996 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
5c7f4665 997 Double_t aa = TMath::Power(yy,kP4);
030b4415 998 Double_t bb = TMath::Power((1.0/bg),kP5);
5c7f4665 999 bb = TMath::Log(kP3 + bb);
030b4415 1000 return ((kP2 - aa - bb) * kP1 / aa);
5c7f4665 1001 }
f73816f5 1002 else {
1003 return kBBMax;
1004 }
d3f347ff 1005
fe4da5cc 1006}
5c7f4665 1007
1008//_____________________________________________________________________________
c4214bc0 1009Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
a328fff9 1010{
1011 //
1012 // Return dN/dx (number of primary collisions per centimeter)
1013 // for given beta*gamma factor.
1014 //
1015 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1016 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1017 // This must be used as a set with IntSpecGeant.
1018 //
1019
030b4415 1020 Int_t i = 0;
a328fff9 1021
030b4415 1022 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1023 , 1.800000, 2.000000, 2.500000, 3.000000
1024 , 4.000000, 7.000000, 10.000000, 20.000000
1025 , 40.000000, 70.000000, 100.000000, 300.000000
1026 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
a328fff9 1027
030b4415 1028 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1029 , 22.734999, 21.411915, 19.934095, 19.449375
1030 , 19.344431, 20.185553, 21.027925, 22.912676
1031 , 24.933352, 26.504053, 27.387468, 29.566597
1032 , 30.353779, 30.787134, 31.129285, 31.157350 };
1033
1034 // Betagamma to gamma
1035 Double_t g = TMath::Sqrt(1.0 + bg*bg);
a328fff9 1036
1037 // Find the index just before the point we need.
030b4415 1038 for (i = 0; i < 18; i++) {
1039 if ((arrG[i] < g) &&
1040 (arrG[i+1] > g)) {
a328fff9 1041 break;
030b4415 1042 }
1043 }
a328fff9 1044
1045 // Simple interpolation.
030b4415 1046 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1047 * (g - arrG[i]) + arrNC[i];
a328fff9 1048
030b4415 1049 return pp;
a328fff9 1050
1051}
1052
1053//_____________________________________________________________________________
5c7f4665 1054Double_t Ermilova(Double_t *x, Double_t *)
1055{
1056 //
1057 // Calculates the delta-ray energy distribution according to Ermilova.
1058 // Logarithmic scale !
1059 //
1060
1061 Double_t energy;
1062 Double_t dpos;
1063 Double_t dnde;
1064
030b4415 1065 Int_t pos1;
1066 Int_t pos2;
5c7f4665 1067
8230f242 1068 const Int_t kNv = 31;
5c7f4665 1069
030b4415 1070 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1071 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1072 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1073 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1074 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1075 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1076 , 11.5129 };
1077
1078 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1079 , 20.9, 20.8, 20.0, 16.0, 11.0
1080 , 8.0, 6.0, 5.2, 4.6, 4.0
1081 , 3.5, 3.0, 1.4, 0.67, 0.44
1082 , 0.3, 0.18, 0.12, 0.08, 0.056
1083 , 0.04, 0.023, 0.015, 0.011, 0.01
1084 , 0.004 };
5c7f4665 1085
1086 energy = x[0];
1087
1088 // Find the position
030b4415 1089 pos1 = 0;
1090 pos2 = 0;
5c7f4665 1091 dpos = 0;
1092 do {
1093 dpos = energy - vxe[pos2++];
1094 }
1095 while (dpos > 0);
1096 pos2--;
030b4415 1097 if (pos2 > kNv) {
1098 pos2 = kNv - 1;
1099 }
5c7f4665 1100 pos1 = pos2 - 1;
1101
1102 // Differentiate between the sampling points
1103 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1104
1105 return dnde;
1106
1107}
a328fff9 1108
1109//_____________________________________________________________________________
1110Double_t IntSpecGeant(Double_t *x, Double_t *)
1111{
1112 //
1113 // Integrated spectrum from Geant3
1114 //
1115
96efaf83 1116 const Int_t npts = 83;
030b4415 1117 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1118 , 2.672067, 2.813299, 3.015059, 3.216819
1119 , 3.418579, 3.620338, 3.868209, 3.920198
1120 , 3.978284, 4.063923, 4.186264, 4.308605
1121 , 4.430946, 4.553288, 4.724261, 4.837736
1122 , 4.999842, 5.161949, 5.324056, 5.486163
1123 , 5.679688, 5.752998, 5.857728, 5.962457
1124 , 6.067185, 6.171914, 6.315653, 6.393674
1125 , 6.471694, 6.539689, 6.597658, 6.655627
1126 , 6.710957, 6.763648, 6.816338, 6.876198
1127 , 6.943227, 7.010257, 7.106285, 7.252151
1128 , 7.460531, 7.668911, 7.877290, 8.085670
1129 , 8.302979, 8.353585, 8.413120, 8.483500
1130 , 8.541030, 8.592857, 8.668865, 8.820485
1131 , 9.037086, 9.253686, 9.470286, 9.686887
1132 , 9.930838, 9.994655, 10.085822, 10.176990
1133 , 10.268158, 10.359325, 10.503614, 10.627565
1134 , 10.804637, 10.981709, 11.158781, 11.335854
1135 , 11.593397, 11.781165, 12.049404, 12.317644
1136 , 12.585884, 12.854123, 14.278421, 16.975889
1137 , 20.829416, 24.682943, 28.536469 };
1138
1139 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1140 , 9.1601500, 8.206670, 6.919630, 5.655430
1141 , 4.6221300, 3.777610, 3.019560, 2.591950
1142 , 2.5414600, 2.712920, 3.327460, 4.928240
1143 , 7.6185300, 10.966700, 12.225800, 8.094750
1144 , 3.3586900, 1.553650, 1.209600, 1.263840
1145 , 1.3241100, 1.312140, 1.255130, 1.165770
1146 , 1.0594500, 0.945450, 0.813231, 0.699837
1147 , 0.6235580, 2.260990, 2.968350, 2.240320
1148 , 1.7988300, 1.553300, 1.432070, 1.535520
1149 , 1.4429900, 1.247990, 1.050750, 0.829549
1150 , 0.5900280, 0.395897, 0.268741, 0.185320
1151 , 0.1292120, 0.103545, 0.0949525, 0.101535
1152 , 0.1276380, 0.134216, 0.123816, 0.104557
1153 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1154 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1155 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1156 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1157 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1158 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1159 , 3.63304e-06, 0.0000000, 0.0000000 };
1160
1161 Int_t i;
a328fff9 1162 Double_t energy = x[0];
a328fff9 1163
030b4415 1164 for (i = 0; i < npts; i++) {
1165 if (energy < arre[i]) {
1166 break;
1167 }
1168 }
a328fff9 1169
030b4415 1170 if (i == 0) {
1171 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");
1172 }
a328fff9 1173
96efaf83 1174 return arrdnde[i];
a328fff9 1175
1176}