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Include the bug fixes by Oliver in the TR simulation
[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
16/*
17$Log$
842287f2 18Revision 1.41 2003/04/23 15:19:48 cblume
19Fix bug in absorbtion length of photons
20
541f5ca4 21Revision 1.40 2003/04/08 08:14:53 morsch
22AddTrackReference moved to AliModule.
23
151f4c41 24Revision 1.39 2003/02/11 16:54:07 hristov
25Updated AliTrackReference class (S.Radomski)
26
2d74ba4f 27Revision 1.38 2003/01/31 11:41:06 cblume
28Fix bug in StepManager in treating geometry with holes
29
e644678a 30Revision 1.37 2003/01/28 14:38:18 cblume
31Add track length to track references
32
87128f38 33Revision 1.36 2002/11/21 22:38:47 alibrary
34Removing AliMC and AliMCProcess
35
4c475d27 36Revision 1.35 2002/10/14 14:57:44 hristov
37Merging the VirtualMC branch to the main development branch (HEAD)
38
b9d0a01d 39Revision 1.33.6.2 2002/07/24 10:09:31 alibrary
40Updating VirtualMC
41
42Revision 1.34 2002/06/13 08:11:56 cblume
43Add the track references
44
c61f1a66 45Revision 1.33 2002/02/20 14:01:40 hristov
46Compare a TString with a string, otherwise the conversion cannot be done on Sun
47
e6674585 48Revision 1.32 2002/02/13 16:58:37 cblume
49Bug fix reported by Jiri. Make atoi input zero terminated in StepManager()
50
593a9fc3 51Revision 1.31 2002/02/11 14:25:27 cblume
52Geometry update, compressed hit structure
53
332e9569 54Revision 1.30 2001/05/21 16:45:47 hristov
55Last minute changes (C.Blume)
56
db30bf0f 57Revision 1.29 2001/05/16 14:57:28 alibrary
58New files for folders and Stack
59
9e1a0ddb 60Revision 1.28 2001/05/07 08:03:22 cblume
61Generate also hits in the amplification region
62
f73816f5 63Revision 1.27 2001/03/30 14:40:15 cblume
64Update of the digitization parameter
65
a3c76cdc 66Revision 1.26 2000/11/30 17:38:08 cblume
67Changes to get in line with new STEER and EVGEN
68
1819f4bb 69Revision 1.25 2000/11/15 14:30:16 cblume
70Fixed bug in calculating detector no. of extra hit
71
990e4068 72Revision 1.24 2000/11/10 14:58:36 cblume
73Introduce additional hit with amplitude 0 at the chamber borders
74
769257f4 75Revision 1.23 2000/11/01 14:53:21 cblume
76Merge with TRD-develop
77
793ff80c 78Revision 1.17.2.5 2000/10/15 23:40:01 cblume
79Remove AliTRDconst
80
81Revision 1.17.2.4 2000/10/06 16:49:46 cblume
82Made Getters const
83
84Revision 1.17.2.3 2000/10/04 16:34:58 cblume
85Replace include files by forward declarations
86
87Revision 1.17.2.2 2000/09/18 13:50:17 cblume
88Include TR photon generation and adapt to new AliTRDhit
89
90Revision 1.22 2000/06/27 13:08:50 cblume
91Changed to Copy(TObject &A) to appease the HP-compiler
92
43da34c0 93Revision 1.21 2000/06/09 11:10:07 cblume
94Compiler warnings and coding conventions, next round
95
dd9a6ee3 96Revision 1.20 2000/06/08 18:32:58 cblume
97Make code compliant to coding conventions
98
8230f242 99Revision 1.19 2000/06/07 16:27:32 cblume
100Try to remove compiler warnings on Sun and HP
101
9d0b222b 102Revision 1.18 2000/05/08 16:17:27 cblume
103Merge TRD-develop
104
6f1e466d 105Revision 1.17.2.1 2000/05/08 14:59:16 cblume
106Made inline function non-virtual. Bug fix in setting sensitive chamber
107
108Revision 1.17 2000/02/28 19:10:26 cblume
109Include the new TRD classes
110
851d3db9 111Revision 1.16.4.1 2000/02/28 18:04:35 cblume
112Change to new hit version, introduce geometry class, and move digitization and clustering to AliTRDdigitizer/AliTRDclusterizerV1
113
114Revision 1.16 1999/11/05 22:50:28 fca
115Do not use Atan, removed from ROOT too
116
90f8d287 117Revision 1.15 1999/11/02 17:20:19 fca
118initialise nbytes before using it
119
036da493 120Revision 1.14 1999/11/02 17:15:54 fca
121Correct ansi scoping not accepted by HP compilers
122
0549c011 123Revision 1.13 1999/11/02 17:14:51 fca
124Correct ansi scoping not accepted by HP compilers
125
9c767df4 126Revision 1.12 1999/11/02 16:35:56 fca
127New version of TRD introduced
128
5c7f4665 129Revision 1.11 1999/11/01 20:41:51 fca
130Added protections against using the wrong version of FRAME
131
ab76897d 132Revision 1.10 1999/09/29 09:24:35 fca
133Introduction of the Copyright and cvs Log
134
4c039060 135*/
136
fe4da5cc 137///////////////////////////////////////////////////////////////////////////////
138// //
769257f4 139// Transition Radiation Detector version 1 -- slow simulator //
fe4da5cc 140// //
141//Begin_Html
142/*
5c7f4665 143<img src="picts/AliTRDfullClass.gif">
fe4da5cc 144*/
145//End_Html
146// //
147// //
148///////////////////////////////////////////////////////////////////////////////
149
769257f4 150#include <stdlib.h>
151
fe4da5cc 152#include <TMath.h>
fe4da5cc 153#include <TVector.h>
5c7f4665 154#include <TRandom.h>
793ff80c 155#include <TF1.h>
1819f4bb 156#include <TLorentzVector.h>
fe4da5cc 157
fe4da5cc 158#include "AliRun.h"
d3f347ff 159#include "AliConst.h"
5c7f4665 160
851d3db9 161#include "AliTRDv1.h"
793ff80c 162#include "AliTRDhit.h"
851d3db9 163#include "AliTRDmatrix.h"
164#include "AliTRDgeometry.h"
793ff80c 165#include "AliTRDsim.h"
851d3db9 166
fe4da5cc 167ClassImp(AliTRDv1)
8230f242 168
169//_____________________________________________________________________________
170AliTRDv1::AliTRDv1():AliTRD()
171{
172 //
173 // Default constructor
174 //
175
8230f242 176 fSensSelect = 0;
177 fSensPlane = -1;
178 fSensChamber = -1;
179 fSensSector = -1;
180 fSensSectorRange = 0;
181
182 fDeltaE = NULL;
793ff80c 183 fTR = NULL;
8230f242 184
185}
186
fe4da5cc 187//_____________________________________________________________________________
188AliTRDv1::AliTRDv1(const char *name, const char *title)
189 :AliTRD(name, title)
190{
191 //
851d3db9 192 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 193 //
82bbf98a 194
9d0b222b 195 fSensSelect = 0;
196 fSensPlane = -1;
197 fSensChamber = -1;
198 fSensSector = -1;
8230f242 199 fSensSectorRange = 0;
5c7f4665 200
9d0b222b 201 fDeltaE = NULL;
793ff80c 202 fTR = NULL;
5c7f4665 203
204 SetBufferSize(128000);
205
206}
207
8230f242 208//_____________________________________________________________________________
dd9a6ee3 209AliTRDv1::AliTRDv1(const AliTRDv1 &trd)
8230f242 210{
211 //
212 // Copy constructor
213 //
214
dd9a6ee3 215 ((AliTRDv1 &) trd).Copy(*this);
8230f242 216
217}
218
5c7f4665 219//_____________________________________________________________________________
220AliTRDv1::~AliTRDv1()
221{
dd9a6ee3 222 //
223 // AliTRDv1 destructor
224 //
82bbf98a 225
5c7f4665 226 if (fDeltaE) delete fDeltaE;
793ff80c 227 if (fTR) delete fTR;
82bbf98a 228
fe4da5cc 229}
230
dd9a6ee3 231//_____________________________________________________________________________
232AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
233{
234 //
235 // Assignment operator
236 //
237
238 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
239 return *this;
240
241}
8230f242 242
243//_____________________________________________________________________________
43da34c0 244void AliTRDv1::Copy(TObject &trd)
8230f242 245{
246 //
247 // Copy function
248 //
249
43da34c0 250 ((AliTRDv1 &) trd).fSensSelect = fSensSelect;
251 ((AliTRDv1 &) trd).fSensPlane = fSensPlane;
252 ((AliTRDv1 &) trd).fSensChamber = fSensChamber;
253 ((AliTRDv1 &) trd).fSensSector = fSensSector;
254 ((AliTRDv1 &) trd).fSensSectorRange = fSensSectorRange;
8230f242 255
793ff80c 256 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
257 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 258
259}
260
fe4da5cc 261//_____________________________________________________________________________
262void AliTRDv1::CreateGeometry()
263{
264 //
851d3db9 265 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 266 // This version covers the full azimuth.
d3f347ff 267 //
268
82bbf98a 269 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 270 AliModule* frame = gAlice->GetModule("FRAME");
271 if (!frame) return;
d3f347ff 272
82bbf98a 273 // Define the chambers
274 AliTRD::CreateGeometry();
d3f347ff 275
fe4da5cc 276}
277
278//_____________________________________________________________________________
279void AliTRDv1::CreateMaterials()
280{
281 //
851d3db9 282 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 283 //
82bbf98a 284
d3f347ff 285 AliTRD::CreateMaterials();
82bbf98a 286
fe4da5cc 287}
288
793ff80c 289//_____________________________________________________________________________
290void AliTRDv1::CreateTRhit(Int_t det)
291{
292 //
293 // Creates an electron cluster from a TR photon.
294 // The photon is assumed to be created a the end of the radiator. The
295 // distance after which it deposits its energy takes into account the
296 // absorbtion of the entrance window and of the gas mixture in drift
297 // volume.
298 //
299
300 // PDG code electron
301 const Int_t kPdgElectron = 11;
302
303 // Ionization energy
304 const Float_t kWion = 22.04;
305
306 // Maximum number of TR photons per track
307 const Int_t kNTR = 50;
308
309 TLorentzVector mom, pos;
793ff80c 310
793ff80c 311 // Create TR at the entrance of the chamber
312 if (gMC->IsTrackEntering()) {
313
f73816f5 314 // Create TR only for electrons
315 Int_t iPdg = gMC->TrackPid();
316 if (TMath::Abs(iPdg) != kPdgElectron) return;
317
793ff80c 318 Float_t eTR[kNTR];
319 Int_t nTR;
320
321 // Create TR photons
322 gMC->TrackMomentum(mom);
323 Float_t pTot = mom.Rho();
324 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
325 if (nTR > kNTR) {
326 printf("AliTRDv1::CreateTRhit -- ");
327 printf("Boundary error: nTR = %d, kNTR = %d\n",nTR,kNTR);
328 exit(1);
329 }
330
331 // Loop through the TR photons
332 for (Int_t iTR = 0; iTR < nTR; iTR++) {
333
334 Float_t energyMeV = eTR[iTR] * 0.001;
335 Float_t energyeV = eTR[iTR] * 1000.0;
336 Float_t absLength = 0;
337 Float_t sigma = 0;
338
339 // Take the absorbtion in the entrance window into account
340 Double_t muMy = fTR->GetMuMy(energyMeV);
341 sigma = muMy * fFoilDensity;
842287f2 342 if (sigma > 0.0) {
343 absLength = gRandom->Exp(1.0/sigma);
344 if (absLength < AliTRDgeometry::MyThick()) continue;
345 }
346 else {
347 continue;
348 }
793ff80c 349
350 // The absorbtion cross sections in the drift gas
351 if (fGasMix == 1) {
352 // Gas-mixture (Xe/CO2)
353 Double_t muXe = fTR->GetMuXe(energyMeV);
354 Double_t muCO = fTR->GetMuCO(energyMeV);
842287f2 355 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
793ff80c 356 }
357 else {
358 // Gas-mixture (Xe/Isobutane)
359 Double_t muXe = fTR->GetMuXe(energyMeV);
360 Double_t muBu = fTR->GetMuBu(energyMeV);
842287f2 361 sigma = (0.97 * muXe + 0.03 * muBu) * fGasDensity * fTR->GetTemp();
793ff80c 362 }
363
364 // The distance after which the energy of the TR photon
365 // is deposited.
842287f2 366 if (sigma > 0.0) {
367 absLength = gRandom->Exp(1.0/sigma);
368 if (absLength > AliTRDgeometry::DrThick()) continue;
369 }
370 else {
371 continue;
372 }
793ff80c 373
374 // The position of the absorbtion
375 Float_t posHit[3];
376 gMC->TrackPosition(pos);
377 posHit[0] = pos[0] + mom[0] / pTot * absLength;
378 posHit[1] = pos[1] + mom[1] / pTot * absLength;
379 posHit[2] = pos[2] + mom[2] / pTot * absLength;
380
381 // Create the charge
382 Int_t q = ((Int_t) (energyeV / kWion));
383
384 // Add the hit to the array. TR photon hits are marked
385 // by negative charge
332e9569 386 AddHit(gAlice->CurrentTrack(),det,posHit,-q,kTRUE);
793ff80c 387
388 }
389
390 }
391
392}
393
5c7f4665 394//_____________________________________________________________________________
395void AliTRDv1::Init()
396{
397 //
398 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 399 //
400
401 AliTRD::Init();
402
9e1a0ddb 403 if(fDebug) printf("%s: Slow simulator\n",ClassName());
851d3db9 404 if (fSensSelect) {
405 if (fSensPlane >= 0)
406 printf(" Only plane %d is sensitive\n",fSensPlane);
407 if (fSensChamber >= 0)
408 printf(" Only chamber %d is sensitive\n",fSensChamber);
9d0b222b 409 if (fSensSector >= 0) {
410 Int_t sens1 = fSensSector;
411 Int_t sens2 = fSensSector + fSensSectorRange;
793ff80c 412 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
413 * AliTRDgeometry::Nsect();
9d0b222b 414 printf(" Only sectors %d - %d are sensitive\n",sens1,sens2-1);
415 }
851d3db9 416 }
793ff80c 417 if (fTR)
9e1a0ddb 418 printf("%s: TR simulation on\n",ClassName());
793ff80c 419 else
9e1a0ddb 420 printf("%s: TR simulation off\n",ClassName());
851d3db9 421 printf("\n");
5c7f4665 422
423 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
424 const Float_t kPoti = 12.1;
425 // Maximum energy (50 keV);
426 const Float_t kEend = 50000.0;
427 // Ermilova distribution for the delta-ray spectrum
8230f242 428 Float_t poti = TMath::Log(kPoti);
429 Float_t eEnd = TMath::Log(kEend);
793ff80c 430 fDeltaE = new TF1("deltae",Ermilova,poti,eEnd,0);
5c7f4665 431
9e1a0ddb 432 if(fDebug) {
433 printf("%s: ",ClassName());
434 for (Int_t i = 0; i < 80; i++) printf("*");
435 printf("\n");
436 }
5c7f4665 437
fe4da5cc 438}
439
793ff80c 440//_____________________________________________________________________________
441AliTRDsim *AliTRDv1::CreateTR()
442{
443 //
444 // Enables the simulation of TR
445 //
446
447 fTR = new AliTRDsim();
448 return fTR;
449
450}
451
5c7f4665 452//_____________________________________________________________________________
453void AliTRDv1::SetSensPlane(Int_t iplane)
454{
455 //
851d3db9 456 // Defines the hit-sensitive plane (0-5)
5c7f4665 457 //
82bbf98a 458
851d3db9 459 if ((iplane < 0) || (iplane > 5)) {
5c7f4665 460 printf("Wrong input value: %d\n",iplane);
461 printf("Use standard setting\n");
851d3db9 462 fSensPlane = -1;
463 fSensSelect = 0;
5c7f4665 464 return;
465 }
82bbf98a 466
5c7f4665 467 fSensSelect = 1;
468 fSensPlane = iplane;
82bbf98a 469
5c7f4665 470}
471
472//_____________________________________________________________________________
473void AliTRDv1::SetSensChamber(Int_t ichamber)
474{
475 //
851d3db9 476 // Defines the hit-sensitive chamber (0-4)
5c7f4665 477 //
478
851d3db9 479 if ((ichamber < 0) || (ichamber > 4)) {
5c7f4665 480 printf("Wrong input value: %d\n",ichamber);
481 printf("Use standard setting\n");
851d3db9 482 fSensChamber = -1;
483 fSensSelect = 0;
5c7f4665 484 return;
485 }
486
487 fSensSelect = 1;
488 fSensChamber = ichamber;
489
490}
491
492//_____________________________________________________________________________
493void AliTRDv1::SetSensSector(Int_t isector)
494{
495 //
851d3db9 496 // Defines the hit-sensitive sector (0-17)
5c7f4665 497 //
498
9d0b222b 499 SetSensSector(isector,1);
500
501}
502
503//_____________________________________________________________________________
504void AliTRDv1::SetSensSector(Int_t isector, Int_t nsector)
505{
506 //
507 // Defines a range of hit-sensitive sectors. The range is defined by
508 // <isector> (0-17) as the starting point and <nsector> as the number
509 // of sectors to be included.
510 //
511
851d3db9 512 if ((isector < 0) || (isector > 17)) {
9d0b222b 513 printf("Wrong input value <isector>: %d\n",isector);
5c7f4665 514 printf("Use standard setting\n");
9d0b222b 515 fSensSector = -1;
516 fSensSectorRange = 0;
517 fSensSelect = 0;
5c7f4665 518 return;
519 }
520
9d0b222b 521 if ((nsector < 1) || (nsector > 18)) {
522 printf("Wrong input value <nsector>: %d\n",nsector);
523 printf("Use standard setting\n");
524 fSensSector = -1;
525 fSensSectorRange = 0;
526 fSensSelect = 0;
527 return;
528 }
529
530 fSensSelect = 1;
531 fSensSector = isector;
532 fSensSectorRange = nsector;
5c7f4665 533
534}
535
536//_____________________________________________________________________________
537void AliTRDv1::StepManager()
538{
539 //
5c7f4665 540 // Slow simulator. Every charged track produces electron cluster as hits
541 // along its path across the drift volume. The step size is set acording
542 // to Bethe-Bloch. The energy distribution of the delta electrons follows
543 // a spectrum taken from Ermilova et al.
544 //
545
851d3db9 546 Int_t pla = 0;
547 Int_t cha = 0;
548 Int_t sec = 0;
793ff80c 549 Int_t det = 0;
851d3db9 550 Int_t iPdg;
793ff80c 551 Int_t qTot;
5c7f4665 552
793ff80c 553 Float_t hits[3];
b9d0a01d 554 Double_t random[1];
5c7f4665 555 Float_t charge;
556 Float_t aMass;
557
f73816f5 558 Double_t pTot = 0;
5c7f4665 559 Double_t eDelta;
560 Double_t betaGamma, pp;
f73816f5 561 Double_t stepSize;
5c7f4665 562
332e9569 563 Bool_t drRegion = kFALSE;
564 Bool_t amRegion = kFALSE;
565
566 TString cIdCurrent;
567 TString cIdSensDr = "J";
568 TString cIdSensAm = "K";
593a9fc3 569 Char_t cIdChamber[3];
570 cIdChamber[2] = 0;
332e9569 571
5c7f4665 572 TLorentzVector pos, mom;
82bbf98a 573
332e9569 574 const Int_t kNplan = AliTRDgeometry::Nplan();
e644678a 575 const Int_t kNcham = AliTRDgeometry::Ncham();
576 const Int_t kNdetsec = kNplan * kNcham;
577
332e9569 578 const Double_t kBig = 1.0E+12;
5c7f4665 579
580 // Ionization energy
a3c76cdc 581 const Float_t kWion = 22.04;
582 // Maximum momentum for e+ e- g
583 const Float_t kPTotMaxEl = 0.002;
f73816f5 584 // Minimum energy for the step size adjustment
585 const Float_t kEkinMinStep = 1.0e-5;
5c7f4665 586 // Plateau value of the energy-loss for electron in xenon
587 // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
588 //const Double_t kPlateau = 1.70;
589 // the averaged value (26/3/99)
a3c76cdc 590 const Float_t kPlateau = 1.55;
5c7f4665 591 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 592 const Float_t kPrim = 48.0;
5c7f4665 593 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 594 const Float_t kPoti = 12.1;
851d3db9 595
596 // PDG code electron
8230f242 597 const Int_t kPdgElectron = 11;
5c7f4665 598
599 // Set the maximum step size to a very large number for all
600 // neutral particles and those outside the driftvolume
601 gMC->SetMaxStep(kBig);
602
603 // Use only charged tracks
604 if (( gMC->TrackCharge() ) &&
605 (!gMC->IsTrackStop() ) &&
606 (!gMC->IsTrackDisappeared())) {
fe4da5cc 607
5c7f4665 608 // Inside a sensitive volume?
332e9569 609 drRegion = kFALSE;
610 amRegion = kFALSE;
611 cIdCurrent = gMC->CurrentVolName();
e6674585 612 if (cIdSensDr == cIdCurrent[1]) {
332e9569 613 drRegion = kTRUE;
614 }
e6674585 615 if (cIdSensAm == cIdCurrent[1]) {
332e9569 616 amRegion = kTRUE;
617 }
618 if (drRegion || amRegion) {
fe4da5cc 619
5c7f4665 620 // The hit coordinates and charge
621 gMC->TrackPosition(pos);
622 hits[0] = pos[0];
623 hits[1] = pos[1];
624 hits[2] = pos[2];
5c7f4665 625
851d3db9 626 // The sector number (0 - 17)
627 // The numbering goes clockwise and starts at y = 0
628 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
629 if (phi < 90.)
630 phi = phi + 270.;
631 else
632 phi = phi - 90.;
633 sec = ((Int_t) (phi / 20));
82bbf98a 634
332e9569 635 // The plane and chamber number
636 cIdChamber[0] = cIdCurrent[2];
637 cIdChamber[1] = cIdCurrent[3];
e644678a 638 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
332e9569 639 cha = ((Int_t) idChamber / kNplan);
640 pla = ((Int_t) idChamber % kNplan);
82bbf98a 641
5c7f4665 642 // Check on selected volumes
643 Int_t addthishit = 1;
644 if (fSensSelect) {
6f1e466d 645 if ((fSensPlane >= 0) && (pla != fSensPlane )) addthishit = 0;
646 if ((fSensChamber >= 0) && (cha != fSensChamber)) addthishit = 0;
9d0b222b 647 if (fSensSector >= 0) {
648 Int_t sens1 = fSensSector;
649 Int_t sens2 = fSensSector + fSensSectorRange;
793ff80c 650 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
651 * AliTRDgeometry::Nsect();
9d0b222b 652 if (sens1 < sens2) {
653 if ((sec < sens1) || (sec >= sens2)) addthishit = 0;
654 }
655 else {
656 if ((sec < sens1) && (sec >= sens2)) addthishit = 0;
657 }
658 }
5c7f4665 659 }
660
661 // Add this hit
662 if (addthishit) {
663
f73816f5 664 // The detector number
793ff80c 665 det = fGeometry->GetDetector(pla,cha,sec);
666
f73816f5 667 // Special hits and TR photons only in the drift region
332e9569 668 if (drRegion) {
f73816f5 669
c61f1a66 670 // Create a track reference at the entrance and
671 // exit of each chamber that contain the
672 // momentum components of the particle
f73816f5 673 if (gMC->IsTrackEntering() || gMC->IsTrackExiting()) {
674 gMC->TrackMomentum(mom);
151f4c41 675 AddTrackReference(gAlice->CurrentTrack());
f73816f5 676 }
677
678 // Create the hits from TR photons
679 if (fTR) CreateTRhit(det);
680
681 }
682
683 // Calculate the energy of the delta-electrons
684 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
685 eDelta = TMath::Max(eDelta,0.0);
686
687 // The number of secondary electrons created
688 qTot = ((Int_t) (eDelta / kWion) + 1);
689
690 // Create a new dEdx hit
332e9569 691 if (drRegion) {
692 AddHit(gAlice->CurrentTrack(),det,hits,qTot,kTRUE);
f73816f5 693 }
5c7f4665 694 else {
332e9569 695 AddHit(gAlice->CurrentTrack(),det,hits,qTot,kFALSE);
f73816f5 696 }
697
5c7f4665 698 // Calculate the maximum step size for the next tracking step
f73816f5 699 // Produce only one hit if Ekin is below cutoff
700 aMass = gMC->TrackMass();
701 if ((gMC->Etot() - aMass) > kEkinMinStep) {
702
703 // The energy loss according to Bethe Bloch
704 iPdg = TMath::Abs(gMC->TrackPid());
705 if ( (iPdg != kPdgElectron) ||
706 ((iPdg == kPdgElectron) && (pTot < kPTotMaxEl))) {
707 gMC->TrackMomentum(mom);
708 pTot = mom.Rho();
709 betaGamma = pTot / aMass;
710 pp = kPrim * BetheBloch(betaGamma);
711 // Take charge > 1 into account
712 charge = gMC->TrackCharge();
713 if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
714 }
715 // Electrons above 20 Mev/c are at the plateau
716 else {
717 pp = kPrim * kPlateau;
718 }
719
720 if (pp > 0) {
721 do
b9d0a01d 722 gMC->GetRandom()->RndmArray(1, random);
f73816f5 723 while ((random[0] == 1.) || (random[0] == 0.));
724 stepSize = - TMath::Log(random[0]) / pp;
725 gMC->SetMaxStep(stepSize);
726 }
727
5c7f4665 728 }
729
730 }
d3f347ff 731
732 }
733
5c7f4665 734 }
735
736}
737
738//_____________________________________________________________________________
739Double_t AliTRDv1::BetheBloch(Double_t bg)
740{
741 //
742 // Parametrization of the Bethe-Bloch-curve
743 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
744 //
745
746 // This parameters have been adjusted to averaged values from GEANT
747 const Double_t kP1 = 7.17960e-02;
748 const Double_t kP2 = 8.54196;
749 const Double_t kP3 = 1.38065e-06;
750 const Double_t kP4 = 5.30972;
751 const Double_t kP5 = 2.83798;
752
753 // This parameters have been adjusted to Xe-data found in:
754 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
755 //const Double_t kP1 = 0.76176E-1;
756 //const Double_t kP2 = 10.632;
757 //const Double_t kP3 = 3.17983E-6;
758 //const Double_t kP4 = 1.8631;
759 //const Double_t kP5 = 1.9479;
760
f73816f5 761 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
762 const Double_t kBgMin = 0.8;
763 const Double_t kBBMax = 6.83298;
764 //const Double_t kBgMin = 0.6;
765 //const Double_t kBBMax = 17.2809;
766 //const Double_t kBgMin = 0.4;
767 //const Double_t kBBMax = 82.0;
768
769 if (bg > kBgMin) {
5c7f4665 770 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
771 Double_t aa = TMath::Power(yy,kP4);
772 Double_t bb = TMath::Power((1./bg),kP5);
773 bb = TMath::Log(kP3 + bb);
774 return ((kP2 - aa - bb)*kP1 / aa);
775 }
f73816f5 776 else {
777 return kBBMax;
778 }
d3f347ff 779
fe4da5cc 780}
5c7f4665 781
782//_____________________________________________________________________________
783Double_t Ermilova(Double_t *x, Double_t *)
784{
785 //
786 // Calculates the delta-ray energy distribution according to Ermilova.
787 // Logarithmic scale !
788 //
789
790 Double_t energy;
791 Double_t dpos;
792 Double_t dnde;
793
794 Int_t pos1, pos2;
795
8230f242 796 const Int_t kNv = 31;
5c7f4665 797
8230f242 798 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
799 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
800 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
801 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
802 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
803 , 9.4727, 9.9035,10.3735,10.5966,10.8198
804 ,11.5129 };
5c7f4665 805
8230f242 806 Float_t vye[kNv] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
807 , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
808 , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
809 , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
810 , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
811 , 0.04 , 0.023, 0.015, 0.011, 0.01
812 , 0.004 };
5c7f4665 813
814 energy = x[0];
815
816 // Find the position
817 pos1 = pos2 = 0;
818 dpos = 0;
819 do {
820 dpos = energy - vxe[pos2++];
821 }
822 while (dpos > 0);
823 pos2--;
f73816f5 824 if (pos2 > kNv) pos2 = kNv - 1;
5c7f4665 825 pos1 = pos2 - 1;
826
827 // Differentiate between the sampling points
828 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
829
830 return dnde;
831
832}