Minor changes (R.Barbera)
[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$Log$
f73816f5 18Revision 1.27 2001/03/30 14:40:15 cblume
19Update of the digitization parameter
20
a3c76cdc 21Revision 1.26 2000/11/30 17:38:08 cblume
22Changes to get in line with new STEER and EVGEN
23
1819f4bb 24Revision 1.25 2000/11/15 14:30:16 cblume
25Fixed bug in calculating detector no. of extra hit
26
990e4068 27Revision 1.24 2000/11/10 14:58:36 cblume
28Introduce additional hit with amplitude 0 at the chamber borders
29
769257f4 30Revision 1.23 2000/11/01 14:53:21 cblume
31Merge with TRD-develop
32
793ff80c 33Revision 1.17.2.5 2000/10/15 23:40:01 cblume
34Remove AliTRDconst
35
36Revision 1.17.2.4 2000/10/06 16:49:46 cblume
37Made Getters const
38
39Revision 1.17.2.3 2000/10/04 16:34:58 cblume
40Replace include files by forward declarations
41
42Revision 1.17.2.2 2000/09/18 13:50:17 cblume
43Include TR photon generation and adapt to new AliTRDhit
44
45Revision 1.22 2000/06/27 13:08:50 cblume
46Changed to Copy(TObject &A) to appease the HP-compiler
47
43da34c0 48Revision 1.21 2000/06/09 11:10:07 cblume
49Compiler warnings and coding conventions, next round
50
dd9a6ee3 51Revision 1.20 2000/06/08 18:32:58 cblume
52Make code compliant to coding conventions
53
8230f242 54Revision 1.19 2000/06/07 16:27:32 cblume
55Try to remove compiler warnings on Sun and HP
56
9d0b222b 57Revision 1.18 2000/05/08 16:17:27 cblume
58Merge TRD-develop
59
6f1e466d 60Revision 1.17.2.1 2000/05/08 14:59:16 cblume
61Made inline function non-virtual. Bug fix in setting sensitive chamber
62
63Revision 1.17 2000/02/28 19:10:26 cblume
64Include the new TRD classes
65
851d3db9 66Revision 1.16.4.1 2000/02/28 18:04:35 cblume
67Change to new hit version, introduce geometry class, and move digitization and clustering to AliTRDdigitizer/AliTRDclusterizerV1
68
69Revision 1.16 1999/11/05 22:50:28 fca
70Do not use Atan, removed from ROOT too
71
90f8d287 72Revision 1.15 1999/11/02 17:20:19 fca
73initialise nbytes before using it
74
036da493 75Revision 1.14 1999/11/02 17:15:54 fca
76Correct ansi scoping not accepted by HP compilers
77
0549c011 78Revision 1.13 1999/11/02 17:14:51 fca
79Correct ansi scoping not accepted by HP compilers
80
9c767df4 81Revision 1.12 1999/11/02 16:35:56 fca
82New version of TRD introduced
83
5c7f4665 84Revision 1.11 1999/11/01 20:41:51 fca
85Added protections against using the wrong version of FRAME
86
ab76897d 87Revision 1.10 1999/09/29 09:24:35 fca
88Introduction of the Copyright and cvs Log
89
4c039060 90*/
91
fe4da5cc 92///////////////////////////////////////////////////////////////////////////////
93// //
769257f4 94// Transition Radiation Detector version 1 -- slow simulator //
fe4da5cc 95// //
96//Begin_Html
97/*
5c7f4665 98<img src="picts/AliTRDfullClass.gif">
fe4da5cc 99*/
100//End_Html
101// //
102// //
103///////////////////////////////////////////////////////////////////////////////
104
769257f4 105#include <stdlib.h>
106
fe4da5cc 107#include <TMath.h>
fe4da5cc 108#include <TVector.h>
5c7f4665 109#include <TRandom.h>
793ff80c 110#include <TF1.h>
1819f4bb 111#include <TLorentzVector.h>
fe4da5cc 112
fe4da5cc 113#include "AliRun.h"
fe4da5cc 114#include "AliMC.h"
d3f347ff 115#include "AliConst.h"
5c7f4665 116
851d3db9 117#include "AliTRDv1.h"
793ff80c 118#include "AliTRDhit.h"
851d3db9 119#include "AliTRDmatrix.h"
120#include "AliTRDgeometry.h"
793ff80c 121#include "AliTRDsim.h"
851d3db9 122
fe4da5cc 123ClassImp(AliTRDv1)
8230f242 124
125//_____________________________________________________________________________
126AliTRDv1::AliTRDv1():AliTRD()
127{
128 //
129 // Default constructor
130 //
131
f73816f5 132 fIdSensDr = 0;
133 fIdSensAm = 0;
8230f242 134
135 fIdChamber1 = 0;
136 fIdChamber2 = 0;
137 fIdChamber3 = 0;
138
139 fSensSelect = 0;
140 fSensPlane = -1;
141 fSensChamber = -1;
142 fSensSector = -1;
143 fSensSectorRange = 0;
144
145 fDeltaE = NULL;
793ff80c 146 fTR = NULL;
8230f242 147
148}
149
fe4da5cc 150//_____________________________________________________________________________
151AliTRDv1::AliTRDv1(const char *name, const char *title)
152 :AliTRD(name, title)
153{
154 //
851d3db9 155 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 156 //
82bbf98a 157
f73816f5 158 fIdSensDr = 0;
159 fIdSensAm = 0;
82bbf98a 160
9d0b222b 161 fIdChamber1 = 0;
162 fIdChamber2 = 0;
163 fIdChamber3 = 0;
5c7f4665 164
9d0b222b 165 fSensSelect = 0;
166 fSensPlane = -1;
167 fSensChamber = -1;
168 fSensSector = -1;
8230f242 169 fSensSectorRange = 0;
5c7f4665 170
9d0b222b 171 fDeltaE = NULL;
793ff80c 172 fTR = NULL;
5c7f4665 173
174 SetBufferSize(128000);
175
176}
177
8230f242 178//_____________________________________________________________________________
dd9a6ee3 179AliTRDv1::AliTRDv1(const AliTRDv1 &trd)
8230f242 180{
181 //
182 // Copy constructor
183 //
184
dd9a6ee3 185 ((AliTRDv1 &) trd).Copy(*this);
8230f242 186
187}
188
5c7f4665 189//_____________________________________________________________________________
190AliTRDv1::~AliTRDv1()
191{
dd9a6ee3 192 //
193 // AliTRDv1 destructor
194 //
82bbf98a 195
5c7f4665 196 if (fDeltaE) delete fDeltaE;
793ff80c 197 if (fTR) delete fTR;
82bbf98a 198
fe4da5cc 199}
200
dd9a6ee3 201//_____________________________________________________________________________
202AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
203{
204 //
205 // Assignment operator
206 //
207
208 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
209 return *this;
210
211}
8230f242 212
213//_____________________________________________________________________________
43da34c0 214void AliTRDv1::Copy(TObject &trd)
8230f242 215{
216 //
217 // Copy function
218 //
219
f73816f5 220 ((AliTRDv1 &) trd).fIdSensDr = fIdSensDr;
221 ((AliTRDv1 &) trd).fIdSensAm = fIdSensAm;
8230f242 222
43da34c0 223 ((AliTRDv1 &) trd).fIdChamber1 = fIdChamber1;
224 ((AliTRDv1 &) trd).fIdChamber2 = fIdChamber2;
225 ((AliTRDv1 &) trd).fIdChamber3 = fIdChamber3;
8230f242 226
43da34c0 227 ((AliTRDv1 &) trd).fSensSelect = fSensSelect;
228 ((AliTRDv1 &) trd).fSensPlane = fSensPlane;
229 ((AliTRDv1 &) trd).fSensChamber = fSensChamber;
230 ((AliTRDv1 &) trd).fSensSector = fSensSector;
231 ((AliTRDv1 &) trd).fSensSectorRange = fSensSectorRange;
8230f242 232
793ff80c 233 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
234 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 235
236}
237
fe4da5cc 238//_____________________________________________________________________________
239void AliTRDv1::CreateGeometry()
240{
241 //
851d3db9 242 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 243 // This version covers the full azimuth.
d3f347ff 244 //
245
82bbf98a 246 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 247 AliModule* frame = gAlice->GetModule("FRAME");
248 if (!frame) return;
d3f347ff 249
82bbf98a 250 // Define the chambers
251 AliTRD::CreateGeometry();
d3f347ff 252
fe4da5cc 253}
254
255//_____________________________________________________________________________
256void AliTRDv1::CreateMaterials()
257{
258 //
851d3db9 259 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 260 //
82bbf98a 261
d3f347ff 262 AliTRD::CreateMaterials();
82bbf98a 263
fe4da5cc 264}
265
793ff80c 266//_____________________________________________________________________________
267void AliTRDv1::CreateTRhit(Int_t det)
268{
269 //
270 // Creates an electron cluster from a TR photon.
271 // The photon is assumed to be created a the end of the radiator. The
272 // distance after which it deposits its energy takes into account the
273 // absorbtion of the entrance window and of the gas mixture in drift
274 // volume.
275 //
276
277 // PDG code electron
278 const Int_t kPdgElectron = 11;
279
280 // Ionization energy
281 const Float_t kWion = 22.04;
282
283 // Maximum number of TR photons per track
284 const Int_t kNTR = 50;
285
286 TLorentzVector mom, pos;
287 TClonesArray &lhits = *fHits;
288
793ff80c 289 // Create TR at the entrance of the chamber
290 if (gMC->IsTrackEntering()) {
291
f73816f5 292 // Create TR only for electrons
293 Int_t iPdg = gMC->TrackPid();
294 if (TMath::Abs(iPdg) != kPdgElectron) return;
295
793ff80c 296 Float_t eTR[kNTR];
297 Int_t nTR;
298
299 // Create TR photons
300 gMC->TrackMomentum(mom);
301 Float_t pTot = mom.Rho();
302 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
303 if (nTR > kNTR) {
304 printf("AliTRDv1::CreateTRhit -- ");
305 printf("Boundary error: nTR = %d, kNTR = %d\n",nTR,kNTR);
306 exit(1);
307 }
308
309 // Loop through the TR photons
310 for (Int_t iTR = 0; iTR < nTR; iTR++) {
311
312 Float_t energyMeV = eTR[iTR] * 0.001;
313 Float_t energyeV = eTR[iTR] * 1000.0;
314 Float_t absLength = 0;
315 Float_t sigma = 0;
316
317 // Take the absorbtion in the entrance window into account
318 Double_t muMy = fTR->GetMuMy(energyMeV);
319 sigma = muMy * fFoilDensity;
320 absLength = gRandom->Exp(sigma);
321 if (absLength < AliTRDgeometry::MyThick()) continue;
322
323 // The absorbtion cross sections in the drift gas
324 if (fGasMix == 1) {
325 // Gas-mixture (Xe/CO2)
326 Double_t muXe = fTR->GetMuXe(energyMeV);
327 Double_t muCO = fTR->GetMuCO(energyMeV);
328 sigma = (0.90 * muXe + 0.10 * muCO) * fGasDensity;
329 }
330 else {
331 // Gas-mixture (Xe/Isobutane)
332 Double_t muXe = fTR->GetMuXe(energyMeV);
333 Double_t muBu = fTR->GetMuBu(energyMeV);
334 sigma = (0.97 * muXe + 0.03 * muBu) * fGasDensity;
335 }
336
337 // The distance after which the energy of the TR photon
338 // is deposited.
339 absLength = gRandom->Exp(sigma);
340 if (absLength > AliTRDgeometry::DrThick()) continue;
341
342 // The position of the absorbtion
343 Float_t posHit[3];
344 gMC->TrackPosition(pos);
345 posHit[0] = pos[0] + mom[0] / pTot * absLength;
346 posHit[1] = pos[1] + mom[1] / pTot * absLength;
347 posHit[2] = pos[2] + mom[2] / pTot * absLength;
348
349 // Create the charge
350 Int_t q = ((Int_t) (energyeV / kWion));
351
352 // Add the hit to the array. TR photon hits are marked
353 // by negative charge
f73816f5 354 AliTRDhit *hit = new(lhits[fNhits++]) AliTRDhit(fIshunt
355 ,gAlice->CurrentTrack()
356 ,det,posHit,-q);
357 hit->SetTRphoton();
793ff80c 358
359 }
360
361 }
362
363}
364
5c7f4665 365//_____________________________________________________________________________
366void AliTRDv1::Init()
367{
368 //
369 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 370 //
371
372 AliTRD::Init();
373
851d3db9 374 printf(" Slow simulator\n\n");
375 if (fSensSelect) {
376 if (fSensPlane >= 0)
377 printf(" Only plane %d is sensitive\n",fSensPlane);
378 if (fSensChamber >= 0)
379 printf(" Only chamber %d is sensitive\n",fSensChamber);
9d0b222b 380 if (fSensSector >= 0) {
381 Int_t sens1 = fSensSector;
382 Int_t sens2 = fSensSector + fSensSectorRange;
793ff80c 383 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
384 * AliTRDgeometry::Nsect();
9d0b222b 385 printf(" Only sectors %d - %d are sensitive\n",sens1,sens2-1);
386 }
851d3db9 387 }
793ff80c 388 if (fTR)
389 printf(" TR simulation on\n");
390 else
391 printf(" TR simulation off\n");
851d3db9 392 printf("\n");
5c7f4665 393
394 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
395 const Float_t kPoti = 12.1;
396 // Maximum energy (50 keV);
397 const Float_t kEend = 50000.0;
398 // Ermilova distribution for the delta-ray spectrum
8230f242 399 Float_t poti = TMath::Log(kPoti);
400 Float_t eEnd = TMath::Log(kEend);
793ff80c 401 fDeltaE = new TF1("deltae",Ermilova,poti,eEnd,0);
5c7f4665 402
403 // Identifier of the sensitive volume (drift region)
f73816f5 404 fIdSensDr = gMC->VolId("UL05");
405 // Identifier of the sensitive volume (amplification region)
406 fIdSensAm = gMC->VolId("UL06");
82bbf98a 407
408 // Identifier of the TRD-driftchambers
409 fIdChamber1 = gMC->VolId("UCIO");
410 fIdChamber2 = gMC->VolId("UCIM");
411 fIdChamber3 = gMC->VolId("UCII");
412
5c7f4665 413 for (Int_t i = 0; i < 80; i++) printf("*");
414 printf("\n");
415
fe4da5cc 416}
417
793ff80c 418//_____________________________________________________________________________
419AliTRDsim *AliTRDv1::CreateTR()
420{
421 //
422 // Enables the simulation of TR
423 //
424
425 fTR = new AliTRDsim();
426 return fTR;
427
428}
429
5c7f4665 430//_____________________________________________________________________________
431void AliTRDv1::SetSensPlane(Int_t iplane)
432{
433 //
851d3db9 434 // Defines the hit-sensitive plane (0-5)
5c7f4665 435 //
82bbf98a 436
851d3db9 437 if ((iplane < 0) || (iplane > 5)) {
5c7f4665 438 printf("Wrong input value: %d\n",iplane);
439 printf("Use standard setting\n");
851d3db9 440 fSensPlane = -1;
441 fSensSelect = 0;
5c7f4665 442 return;
443 }
82bbf98a 444
5c7f4665 445 fSensSelect = 1;
446 fSensPlane = iplane;
82bbf98a 447
5c7f4665 448}
449
450//_____________________________________________________________________________
451void AliTRDv1::SetSensChamber(Int_t ichamber)
452{
453 //
851d3db9 454 // Defines the hit-sensitive chamber (0-4)
5c7f4665 455 //
456
851d3db9 457 if ((ichamber < 0) || (ichamber > 4)) {
5c7f4665 458 printf("Wrong input value: %d\n",ichamber);
459 printf("Use standard setting\n");
851d3db9 460 fSensChamber = -1;
461 fSensSelect = 0;
5c7f4665 462 return;
463 }
464
465 fSensSelect = 1;
466 fSensChamber = ichamber;
467
468}
469
470//_____________________________________________________________________________
471void AliTRDv1::SetSensSector(Int_t isector)
472{
473 //
851d3db9 474 // Defines the hit-sensitive sector (0-17)
5c7f4665 475 //
476
9d0b222b 477 SetSensSector(isector,1);
478
479}
480
481//_____________________________________________________________________________
482void AliTRDv1::SetSensSector(Int_t isector, Int_t nsector)
483{
484 //
485 // Defines a range of hit-sensitive sectors. The range is defined by
486 // <isector> (0-17) as the starting point and <nsector> as the number
487 // of sectors to be included.
488 //
489
851d3db9 490 if ((isector < 0) || (isector > 17)) {
9d0b222b 491 printf("Wrong input value <isector>: %d\n",isector);
5c7f4665 492 printf("Use standard setting\n");
9d0b222b 493 fSensSector = -1;
494 fSensSectorRange = 0;
495 fSensSelect = 0;
5c7f4665 496 return;
497 }
498
9d0b222b 499 if ((nsector < 1) || (nsector > 18)) {
500 printf("Wrong input value <nsector>: %d\n",nsector);
501 printf("Use standard setting\n");
502 fSensSector = -1;
503 fSensSectorRange = 0;
504 fSensSelect = 0;
505 return;
506 }
507
508 fSensSelect = 1;
509 fSensSector = isector;
510 fSensSectorRange = nsector;
5c7f4665 511
512}
513
514//_____________________________________________________________________________
515void AliTRDv1::StepManager()
516{
517 //
5c7f4665 518 // Slow simulator. Every charged track produces electron cluster as hits
519 // along its path across the drift volume. The step size is set acording
520 // to Bethe-Bloch. The energy distribution of the delta electrons follows
521 // a spectrum taken from Ermilova et al.
522 //
523
524 Int_t iIdSens, icSens;
5c7f4665 525 Int_t iIdChamber, icChamber;
851d3db9 526 Int_t pla = 0;
527 Int_t cha = 0;
528 Int_t sec = 0;
793ff80c 529 Int_t det = 0;
851d3db9 530 Int_t iPdg;
793ff80c 531 Int_t qTot;
5c7f4665 532
793ff80c 533 Float_t hits[3];
990e4068 534 Float_t moms[3];
5c7f4665 535 Float_t random[1];
536 Float_t charge;
537 Float_t aMass;
538
f73816f5 539 Double_t pTot = 0;
5c7f4665 540 Double_t eDelta;
541 Double_t betaGamma, pp;
f73816f5 542 Double_t stepSize;
5c7f4665 543
544 TLorentzVector pos, mom;
82bbf98a 545 TClonesArray &lhits = *fHits;
546
851d3db9 547 const Double_t kBig = 1.0E+12;
5c7f4665 548
549 // Ionization energy
a3c76cdc 550 const Float_t kWion = 22.04;
551 // Maximum momentum for e+ e- g
552 const Float_t kPTotMaxEl = 0.002;
f73816f5 553 // Minimum energy for the step size adjustment
554 const Float_t kEkinMinStep = 1.0e-5;
5c7f4665 555 // Plateau value of the energy-loss for electron in xenon
556 // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
557 //const Double_t kPlateau = 1.70;
558 // the averaged value (26/3/99)
a3c76cdc 559 const Float_t kPlateau = 1.55;
5c7f4665 560 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 561 const Float_t kPrim = 48.0;
5c7f4665 562 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 563 const Float_t kPoti = 12.1;
851d3db9 564
565 // PDG code electron
8230f242 566 const Int_t kPdgElectron = 11;
5c7f4665 567
568 // Set the maximum step size to a very large number for all
569 // neutral particles and those outside the driftvolume
570 gMC->SetMaxStep(kBig);
571
572 // Use only charged tracks
573 if (( gMC->TrackCharge() ) &&
574 (!gMC->IsTrackStop() ) &&
575 (!gMC->IsTrackDisappeared())) {
fe4da5cc 576
5c7f4665 577 // Inside a sensitive volume?
82bbf98a 578 iIdSens = gMC->CurrentVolID(icSens);
f73816f5 579 if ((iIdSens == fIdSensDr) ||
580 (iIdSens == fIdSensAm)) {
82bbf98a 581
82bbf98a 582 iIdChamber = gMC->CurrentVolOffID(1,icChamber);
fe4da5cc 583
5c7f4665 584 // The hit coordinates and charge
585 gMC->TrackPosition(pos);
586 hits[0] = pos[0];
587 hits[1] = pos[1];
588 hits[2] = pos[2];
5c7f4665 589
851d3db9 590 // The sector number (0 - 17)
591 // The numbering goes clockwise and starts at y = 0
592 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
593 if (phi < 90.)
594 phi = phi + 270.;
595 else
596 phi = phi - 90.;
597 sec = ((Int_t) (phi / 20));
82bbf98a 598
d3f347ff 599 // The chamber number
851d3db9 600 // 0: outer left
601 // 1: middle left
602 // 2: inner
603 // 3: middle right
604 // 4: outer right
82bbf98a 605 if (iIdChamber == fIdChamber1)
851d3db9 606 cha = (hits[2] < 0 ? 0 : 4);
82bbf98a 607 else if (iIdChamber == fIdChamber2)
851d3db9 608 cha = (hits[2] < 0 ? 1 : 3);
82bbf98a 609 else if (iIdChamber == fIdChamber3)
851d3db9 610 cha = 2;
82bbf98a 611
fe4da5cc 612 // The plane number
851d3db9 613 // The numbering starts at the innermost plane
614 pla = icChamber - TMath::Nint((Float_t) (icChamber / 7)) * 6 - 1;
82bbf98a 615
5c7f4665 616 // Check on selected volumes
617 Int_t addthishit = 1;
618 if (fSensSelect) {
6f1e466d 619 if ((fSensPlane >= 0) && (pla != fSensPlane )) addthishit = 0;
620 if ((fSensChamber >= 0) && (cha != fSensChamber)) addthishit = 0;
9d0b222b 621 if (fSensSector >= 0) {
622 Int_t sens1 = fSensSector;
623 Int_t sens2 = fSensSector + fSensSectorRange;
793ff80c 624 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
625 * AliTRDgeometry::Nsect();
9d0b222b 626 if (sens1 < sens2) {
627 if ((sec < sens1) || (sec >= sens2)) addthishit = 0;
628 }
629 else {
630 if ((sec < sens1) && (sec >= sens2)) addthishit = 0;
631 }
632 }
5c7f4665 633 }
634
635 // Add this hit
636 if (addthishit) {
637
f73816f5 638 // The detector number
793ff80c 639 det = fGeometry->GetDetector(pla,cha,sec);
640
f73816f5 641 // Special hits and TR photons only in the drift region
642 if (iIdSens == fIdSensDr) {
643
644 // Create some special hits with amplitude 0 at the entrance and
645 // exit of each chamber that contain the momentum components of the particle
646 if (gMC->IsTrackEntering() || gMC->IsTrackExiting()) {
647 gMC->TrackMomentum(mom);
648 moms[0] = mom[0];
649 moms[1] = mom[1];
650 moms[2] = mom[2];
651 AliTRDhit *hitTest = new(lhits[fNhits++]) AliTRDhit(fIshunt
652 ,gAlice->CurrentTrack()
653 ,det,moms,0);
654 hitTest->SetTest();
655 }
656
657 // Create the hits from TR photons
658 if (fTR) CreateTRhit(det);
659
660 }
661
662 // Calculate the energy of the delta-electrons
663 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
664 eDelta = TMath::Max(eDelta,0.0);
665
666 // The number of secondary electrons created
667 qTot = ((Int_t) (eDelta / kWion) + 1);
668
669 // Create a new dEdx hit
670 AliTRDhit *hit = new(lhits[fNhits++]) AliTRDhit(fIshunt
671 ,gAlice->CurrentTrack()
672 ,det,hits,qTot);
673 if (iIdSens == fIdSensDr) {
674 hit->SetDrift();
675 }
5c7f4665 676 else {
f73816f5 677 hit->SetAmplification();
678 }
679
5c7f4665 680 // Calculate the maximum step size for the next tracking step
f73816f5 681 // Produce only one hit if Ekin is below cutoff
682 aMass = gMC->TrackMass();
683 if ((gMC->Etot() - aMass) > kEkinMinStep) {
684
685 // The energy loss according to Bethe Bloch
686 iPdg = TMath::Abs(gMC->TrackPid());
687 if ( (iPdg != kPdgElectron) ||
688 ((iPdg == kPdgElectron) && (pTot < kPTotMaxEl))) {
689 gMC->TrackMomentum(mom);
690 pTot = mom.Rho();
691 betaGamma = pTot / aMass;
692 pp = kPrim * BetheBloch(betaGamma);
693 // Take charge > 1 into account
694 charge = gMC->TrackCharge();
695 if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
696 }
697 // Electrons above 20 Mev/c are at the plateau
698 else {
699 pp = kPrim * kPlateau;
700 }
701
702 if (pp > 0) {
703 do
704 gMC->Rndm(random,1);
705 while ((random[0] == 1.) || (random[0] == 0.));
706 stepSize = - TMath::Log(random[0]) / pp;
707 gMC->SetMaxStep(stepSize);
708 }
709
5c7f4665 710 }
711
712 }
d3f347ff 713
714 }
715
5c7f4665 716 }
717
718}
719
720//_____________________________________________________________________________
721Double_t AliTRDv1::BetheBloch(Double_t bg)
722{
723 //
724 // Parametrization of the Bethe-Bloch-curve
725 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
726 //
727
728 // This parameters have been adjusted to averaged values from GEANT
729 const Double_t kP1 = 7.17960e-02;
730 const Double_t kP2 = 8.54196;
731 const Double_t kP3 = 1.38065e-06;
732 const Double_t kP4 = 5.30972;
733 const Double_t kP5 = 2.83798;
734
735 // This parameters have been adjusted to Xe-data found in:
736 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
737 //const Double_t kP1 = 0.76176E-1;
738 //const Double_t kP2 = 10.632;
739 //const Double_t kP3 = 3.17983E-6;
740 //const Double_t kP4 = 1.8631;
741 //const Double_t kP5 = 1.9479;
742
f73816f5 743 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
744 const Double_t kBgMin = 0.8;
745 const Double_t kBBMax = 6.83298;
746 //const Double_t kBgMin = 0.6;
747 //const Double_t kBBMax = 17.2809;
748 //const Double_t kBgMin = 0.4;
749 //const Double_t kBBMax = 82.0;
750
751 if (bg > kBgMin) {
5c7f4665 752 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
753 Double_t aa = TMath::Power(yy,kP4);
754 Double_t bb = TMath::Power((1./bg),kP5);
755 bb = TMath::Log(kP3 + bb);
756 return ((kP2 - aa - bb)*kP1 / aa);
757 }
f73816f5 758 else {
759 return kBBMax;
760 }
d3f347ff 761
fe4da5cc 762}
5c7f4665 763
764//_____________________________________________________________________________
765Double_t Ermilova(Double_t *x, Double_t *)
766{
767 //
768 // Calculates the delta-ray energy distribution according to Ermilova.
769 // Logarithmic scale !
770 //
771
772 Double_t energy;
773 Double_t dpos;
774 Double_t dnde;
775
776 Int_t pos1, pos2;
777
8230f242 778 const Int_t kNv = 31;
5c7f4665 779
8230f242 780 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
781 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
782 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
783 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
784 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
785 , 9.4727, 9.9035,10.3735,10.5966,10.8198
786 ,11.5129 };
5c7f4665 787
8230f242 788 Float_t vye[kNv] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
789 , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
790 , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
791 , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
792 , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
793 , 0.04 , 0.023, 0.015, 0.011, 0.01
794 , 0.004 };
5c7f4665 795
796 energy = x[0];
797
798 // Find the position
799 pos1 = pos2 = 0;
800 dpos = 0;
801 do {
802 dpos = energy - vxe[pos2++];
803 }
804 while (dpos > 0);
805 pos2--;
f73816f5 806 if (pos2 > kNv) pos2 = kNv - 1;
5c7f4665 807 pos1 = pos2 - 1;
808
809 // Differentiate between the sampling points
810 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
811
812 return dnde;
813
814}