Compressed hits structure from Marian
[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$Log$
db30bf0f 18Revision 1.29 2001/05/16 14:57:28 alibrary
19New files for folders and Stack
20
9e1a0ddb 21Revision 1.28 2001/05/07 08:03:22 cblume
22Generate also hits in the amplification region
23
f73816f5 24Revision 1.27 2001/03/30 14:40:15 cblume
25Update of the digitization parameter
26
a3c76cdc 27Revision 1.26 2000/11/30 17:38:08 cblume
28Changes to get in line with new STEER and EVGEN
29
1819f4bb 30Revision 1.25 2000/11/15 14:30:16 cblume
31Fixed bug in calculating detector no. of extra hit
32
990e4068 33Revision 1.24 2000/11/10 14:58:36 cblume
34Introduce additional hit with amplitude 0 at the chamber borders
35
769257f4 36Revision 1.23 2000/11/01 14:53:21 cblume
37Merge with TRD-develop
38
793ff80c 39Revision 1.17.2.5 2000/10/15 23:40:01 cblume
40Remove AliTRDconst
41
42Revision 1.17.2.4 2000/10/06 16:49:46 cblume
43Made Getters const
44
45Revision 1.17.2.3 2000/10/04 16:34:58 cblume
46Replace include files by forward declarations
47
48Revision 1.17.2.2 2000/09/18 13:50:17 cblume
49Include TR photon generation and adapt to new AliTRDhit
50
51Revision 1.22 2000/06/27 13:08:50 cblume
52Changed to Copy(TObject &A) to appease the HP-compiler
53
43da34c0 54Revision 1.21 2000/06/09 11:10:07 cblume
55Compiler warnings and coding conventions, next round
56
dd9a6ee3 57Revision 1.20 2000/06/08 18:32:58 cblume
58Make code compliant to coding conventions
59
8230f242 60Revision 1.19 2000/06/07 16:27:32 cblume
61Try to remove compiler warnings on Sun and HP
62
9d0b222b 63Revision 1.18 2000/05/08 16:17:27 cblume
64Merge TRD-develop
65
6f1e466d 66Revision 1.17.2.1 2000/05/08 14:59:16 cblume
67Made inline function non-virtual. Bug fix in setting sensitive chamber
68
69Revision 1.17 2000/02/28 19:10:26 cblume
70Include the new TRD classes
71
851d3db9 72Revision 1.16.4.1 2000/02/28 18:04:35 cblume
73Change to new hit version, introduce geometry class, and move digitization and clustering to AliTRDdigitizer/AliTRDclusterizerV1
74
75Revision 1.16 1999/11/05 22:50:28 fca
76Do not use Atan, removed from ROOT too
77
90f8d287 78Revision 1.15 1999/11/02 17:20:19 fca
79initialise nbytes before using it
80
036da493 81Revision 1.14 1999/11/02 17:15:54 fca
82Correct ansi scoping not accepted by HP compilers
83
0549c011 84Revision 1.13 1999/11/02 17:14:51 fca
85Correct ansi scoping not accepted by HP compilers
86
9c767df4 87Revision 1.12 1999/11/02 16:35:56 fca
88New version of TRD introduced
89
5c7f4665 90Revision 1.11 1999/11/01 20:41:51 fca
91Added protections against using the wrong version of FRAME
92
ab76897d 93Revision 1.10 1999/09/29 09:24:35 fca
94Introduction of the Copyright and cvs Log
95
4c039060 96*/
97
fe4da5cc 98///////////////////////////////////////////////////////////////////////////////
99// //
769257f4 100// Transition Radiation Detector version 1 -- slow simulator //
fe4da5cc 101// //
102//Begin_Html
103/*
5c7f4665 104<img src="picts/AliTRDfullClass.gif">
fe4da5cc 105*/
106//End_Html
107// //
108// //
109///////////////////////////////////////////////////////////////////////////////
110
769257f4 111#include <stdlib.h>
112
fe4da5cc 113#include <TMath.h>
fe4da5cc 114#include <TVector.h>
5c7f4665 115#include <TRandom.h>
793ff80c 116#include <TF1.h>
1819f4bb 117#include <TLorentzVector.h>
fe4da5cc 118
fe4da5cc 119#include "AliRun.h"
fe4da5cc 120#include "AliMC.h"
d3f347ff 121#include "AliConst.h"
5c7f4665 122
851d3db9 123#include "AliTRDv1.h"
793ff80c 124#include "AliTRDhit.h"
851d3db9 125#include "AliTRDmatrix.h"
126#include "AliTRDgeometry.h"
793ff80c 127#include "AliTRDsim.h"
851d3db9 128
fe4da5cc 129ClassImp(AliTRDv1)
8230f242 130
131//_____________________________________________________________________________
132AliTRDv1::AliTRDv1():AliTRD()
133{
134 //
135 // Default constructor
136 //
137
f73816f5 138 fIdSensDr = 0;
139 fIdSensAm = 0;
8230f242 140
141 fIdChamber1 = 0;
142 fIdChamber2 = 0;
143 fIdChamber3 = 0;
144
145 fSensSelect = 0;
146 fSensPlane = -1;
147 fSensChamber = -1;
148 fSensSector = -1;
149 fSensSectorRange = 0;
150
151 fDeltaE = NULL;
793ff80c 152 fTR = NULL;
8230f242 153
154}
155
fe4da5cc 156//_____________________________________________________________________________
157AliTRDv1::AliTRDv1(const char *name, const char *title)
158 :AliTRD(name, title)
159{
160 //
851d3db9 161 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 162 //
82bbf98a 163
f73816f5 164 fIdSensDr = 0;
165 fIdSensAm = 0;
82bbf98a 166
9d0b222b 167 fIdChamber1 = 0;
168 fIdChamber2 = 0;
169 fIdChamber3 = 0;
5c7f4665 170
9d0b222b 171 fSensSelect = 0;
172 fSensPlane = -1;
173 fSensChamber = -1;
174 fSensSector = -1;
8230f242 175 fSensSectorRange = 0;
5c7f4665 176
9d0b222b 177 fDeltaE = NULL;
793ff80c 178 fTR = NULL;
5c7f4665 179
180 SetBufferSize(128000);
181
182}
183
184//_____________________________________________________________________________
dd9a6ee3 185AliTRDv1::AliTRDv1(const AliTRDv1 &trd)
8230f242 186{
187 //
188 // Copy constructor
189 //
190
dd9a6ee3 191 ((AliTRDv1 &) trd).Copy(*this);
8230f242 192
193}
194
195//_____________________________________________________________________________
5c7f4665 196AliTRDv1::~AliTRDv1()
197{
dd9a6ee3 198 //
199 // AliTRDv1 destructor
200 //
82bbf98a 201
5c7f4665 202 if (fDeltaE) delete fDeltaE;
793ff80c 203 if (fTR) delete fTR;
82bbf98a 204
fe4da5cc 205}
206
dd9a6ee3 207//_____________________________________________________________________________
208AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
209{
210 //
211 // Assignment operator
212 //
213
214 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
215 return *this;
216
217}
8230f242 218
219//_____________________________________________________________________________
43da34c0 220void AliTRDv1::Copy(TObject &trd)
8230f242 221{
222 //
223 // Copy function
224 //
225
f73816f5 226 ((AliTRDv1 &) trd).fIdSensDr = fIdSensDr;
227 ((AliTRDv1 &) trd).fIdSensAm = fIdSensAm;
8230f242 228
43da34c0 229 ((AliTRDv1 &) trd).fIdChamber1 = fIdChamber1;
230 ((AliTRDv1 &) trd).fIdChamber2 = fIdChamber2;
231 ((AliTRDv1 &) trd).fIdChamber3 = fIdChamber3;
8230f242 232
43da34c0 233 ((AliTRDv1 &) trd).fSensSelect = fSensSelect;
234 ((AliTRDv1 &) trd).fSensPlane = fSensPlane;
235 ((AliTRDv1 &) trd).fSensChamber = fSensChamber;
236 ((AliTRDv1 &) trd).fSensSector = fSensSector;
237 ((AliTRDv1 &) trd).fSensSectorRange = fSensSectorRange;
8230f242 238
793ff80c 239 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
240 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 241
242}
243
fe4da5cc 244//_____________________________________________________________________________
245void AliTRDv1::CreateGeometry()
246{
247 //
851d3db9 248 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 249 // This version covers the full azimuth.
d3f347ff 250 //
251
82bbf98a 252 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 253 AliModule* frame = gAlice->GetModule("FRAME");
254 if (!frame) return;
d3f347ff 255
82bbf98a 256 // Define the chambers
257 AliTRD::CreateGeometry();
d3f347ff 258
fe4da5cc 259}
260
261//_____________________________________________________________________________
262void AliTRDv1::CreateMaterials()
263{
264 //
851d3db9 265 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 266 //
82bbf98a 267
d3f347ff 268 AliTRD::CreateMaterials();
82bbf98a 269
fe4da5cc 270}
271
272//_____________________________________________________________________________
793ff80c 273void AliTRDv1::CreateTRhit(Int_t det)
274{
275 //
276 // Creates an electron cluster from a TR photon.
277 // The photon is assumed to be created a the end of the radiator. The
278 // distance after which it deposits its energy takes into account the
279 // absorbtion of the entrance window and of the gas mixture in drift
280 // volume.
281 //
282
283 // PDG code electron
284 const Int_t kPdgElectron = 11;
285
286 // Ionization energy
287 const Float_t kWion = 22.04;
288
289 // Maximum number of TR photons per track
290 const Int_t kNTR = 50;
291
292 TLorentzVector mom, pos;
293 TClonesArray &lhits = *fHits;
294
793ff80c 295 // Create TR at the entrance of the chamber
296 if (gMC->IsTrackEntering()) {
297
f73816f5 298 // Create TR only for electrons
299 Int_t iPdg = gMC->TrackPid();
300 if (TMath::Abs(iPdg) != kPdgElectron) return;
301
793ff80c 302 Float_t eTR[kNTR];
303 Int_t nTR;
304
305 // Create TR photons
306 gMC->TrackMomentum(mom);
307 Float_t pTot = mom.Rho();
308 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
309 if (nTR > kNTR) {
310 printf("AliTRDv1::CreateTRhit -- ");
311 printf("Boundary error: nTR = %d, kNTR = %d\n",nTR,kNTR);
312 exit(1);
313 }
314
315 // Loop through the TR photons
316 for (Int_t iTR = 0; iTR < nTR; iTR++) {
317
318 Float_t energyMeV = eTR[iTR] * 0.001;
319 Float_t energyeV = eTR[iTR] * 1000.0;
320 Float_t absLength = 0;
321 Float_t sigma = 0;
322
323 // Take the absorbtion in the entrance window into account
324 Double_t muMy = fTR->GetMuMy(energyMeV);
325 sigma = muMy * fFoilDensity;
326 absLength = gRandom->Exp(sigma);
327 if (absLength < AliTRDgeometry::MyThick()) continue;
328
329 // The absorbtion cross sections in the drift gas
330 if (fGasMix == 1) {
331 // Gas-mixture (Xe/CO2)
332 Double_t muXe = fTR->GetMuXe(energyMeV);
333 Double_t muCO = fTR->GetMuCO(energyMeV);
db30bf0f 334 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity;
793ff80c 335 }
336 else {
337 // Gas-mixture (Xe/Isobutane)
338 Double_t muXe = fTR->GetMuXe(energyMeV);
339 Double_t muBu = fTR->GetMuBu(energyMeV);
340 sigma = (0.97 * muXe + 0.03 * muBu) * fGasDensity;
341 }
342
343 // The distance after which the energy of the TR photon
344 // is deposited.
345 absLength = gRandom->Exp(sigma);
346 if (absLength > AliTRDgeometry::DrThick()) continue;
347
348 // The position of the absorbtion
349 Float_t posHit[3];
350 gMC->TrackPosition(pos);
351 posHit[0] = pos[0] + mom[0] / pTot * absLength;
352 posHit[1] = pos[1] + mom[1] / pTot * absLength;
353 posHit[2] = pos[2] + mom[2] / pTot * absLength;
354
355 // Create the charge
356 Int_t q = ((Int_t) (energyeV / kWion));
357
358 // Add the hit to the array. TR photon hits are marked
359 // by negative charge
f73816f5 360 AliTRDhit *hit = new(lhits[fNhits++]) AliTRDhit(fIshunt
361 ,gAlice->CurrentTrack()
362 ,det,posHit,-q);
363 hit->SetTRphoton();
793ff80c 364
365 }
366
367 }
368
369}
370
371//_____________________________________________________________________________
5c7f4665 372void AliTRDv1::Init()
373{
374 //
375 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 376 //
377
378 AliTRD::Init();
379
9e1a0ddb 380 if(fDebug) printf("%s: Slow simulator\n",ClassName());
851d3db9 381 if (fSensSelect) {
382 if (fSensPlane >= 0)
383 printf(" Only plane %d is sensitive\n",fSensPlane);
384 if (fSensChamber >= 0)
385 printf(" Only chamber %d is sensitive\n",fSensChamber);
9d0b222b 386 if (fSensSector >= 0) {
387 Int_t sens1 = fSensSector;
388 Int_t sens2 = fSensSector + fSensSectorRange;
793ff80c 389 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
390 * AliTRDgeometry::Nsect();
9d0b222b 391 printf(" Only sectors %d - %d are sensitive\n",sens1,sens2-1);
392 }
851d3db9 393 }
793ff80c 394 if (fTR)
9e1a0ddb 395 printf("%s: TR simulation on\n",ClassName());
793ff80c 396 else
9e1a0ddb 397 printf("%s: TR simulation off\n",ClassName());
851d3db9 398 printf("\n");
5c7f4665 399
400 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
401 const Float_t kPoti = 12.1;
402 // Maximum energy (50 keV);
403 const Float_t kEend = 50000.0;
404 // Ermilova distribution for the delta-ray spectrum
8230f242 405 Float_t poti = TMath::Log(kPoti);
406 Float_t eEnd = TMath::Log(kEend);
793ff80c 407 fDeltaE = new TF1("deltae",Ermilova,poti,eEnd,0);
5c7f4665 408
409 // Identifier of the sensitive volume (drift region)
f73816f5 410 fIdSensDr = gMC->VolId("UL05");
411 // Identifier of the sensitive volume (amplification region)
412 fIdSensAm = gMC->VolId("UL06");
82bbf98a 413
414 // Identifier of the TRD-driftchambers
415 fIdChamber1 = gMC->VolId("UCIO");
416 fIdChamber2 = gMC->VolId("UCIM");
417 fIdChamber3 = gMC->VolId("UCII");
418
9e1a0ddb 419 if(fDebug) {
420 printf("%s: ",ClassName());
421 for (Int_t i = 0; i < 80; i++) printf("*");
422 printf("\n");
423 }
5c7f4665 424
fe4da5cc 425}
426
427//_____________________________________________________________________________
793ff80c 428AliTRDsim *AliTRDv1::CreateTR()
429{
430 //
431 // Enables the simulation of TR
432 //
433
434 fTR = new AliTRDsim();
435 return fTR;
436
437}
438
439//_____________________________________________________________________________
5c7f4665 440void AliTRDv1::SetSensPlane(Int_t iplane)
441{
442 //
851d3db9 443 // Defines the hit-sensitive plane (0-5)
5c7f4665 444 //
82bbf98a 445
851d3db9 446 if ((iplane < 0) || (iplane > 5)) {
5c7f4665 447 printf("Wrong input value: %d\n",iplane);
448 printf("Use standard setting\n");
851d3db9 449 fSensPlane = -1;
450 fSensSelect = 0;
5c7f4665 451 return;
452 }
82bbf98a 453
5c7f4665 454 fSensSelect = 1;
455 fSensPlane = iplane;
82bbf98a 456
5c7f4665 457}
458
459//_____________________________________________________________________________
460void AliTRDv1::SetSensChamber(Int_t ichamber)
461{
462 //
851d3db9 463 // Defines the hit-sensitive chamber (0-4)
5c7f4665 464 //
465
851d3db9 466 if ((ichamber < 0) || (ichamber > 4)) {
5c7f4665 467 printf("Wrong input value: %d\n",ichamber);
468 printf("Use standard setting\n");
851d3db9 469 fSensChamber = -1;
470 fSensSelect = 0;
5c7f4665 471 return;
472 }
473
474 fSensSelect = 1;
475 fSensChamber = ichamber;
476
477}
478
479//_____________________________________________________________________________
480void AliTRDv1::SetSensSector(Int_t isector)
481{
482 //
851d3db9 483 // Defines the hit-sensitive sector (0-17)
5c7f4665 484 //
485
9d0b222b 486 SetSensSector(isector,1);
487
488}
489
490//_____________________________________________________________________________
491void AliTRDv1::SetSensSector(Int_t isector, Int_t nsector)
492{
493 //
494 // Defines a range of hit-sensitive sectors. The range is defined by
495 // <isector> (0-17) as the starting point and <nsector> as the number
496 // of sectors to be included.
497 //
498
851d3db9 499 if ((isector < 0) || (isector > 17)) {
9d0b222b 500 printf("Wrong input value <isector>: %d\n",isector);
5c7f4665 501 printf("Use standard setting\n");
9d0b222b 502 fSensSector = -1;
503 fSensSectorRange = 0;
504 fSensSelect = 0;
5c7f4665 505 return;
506 }
507
9d0b222b 508 if ((nsector < 1) || (nsector > 18)) {
509 printf("Wrong input value <nsector>: %d\n",nsector);
510 printf("Use standard setting\n");
511 fSensSector = -1;
512 fSensSectorRange = 0;
513 fSensSelect = 0;
514 return;
515 }
516
517 fSensSelect = 1;
518 fSensSector = isector;
519 fSensSectorRange = nsector;
5c7f4665 520
521}
522
523//_____________________________________________________________________________
524void AliTRDv1::StepManager()
525{
526 //
5c7f4665 527 // Slow simulator. Every charged track produces electron cluster as hits
528 // along its path across the drift volume. The step size is set acording
529 // to Bethe-Bloch. The energy distribution of the delta electrons follows
530 // a spectrum taken from Ermilova et al.
531 //
532
533 Int_t iIdSens, icSens;
5c7f4665 534 Int_t iIdChamber, icChamber;
851d3db9 535 Int_t pla = 0;
536 Int_t cha = 0;
537 Int_t sec = 0;
793ff80c 538 Int_t det = 0;
851d3db9 539 Int_t iPdg;
793ff80c 540 Int_t qTot;
5c7f4665 541
793ff80c 542 Float_t hits[3];
990e4068 543 Float_t moms[3];
5c7f4665 544 Float_t random[1];
545 Float_t charge;
546 Float_t aMass;
547
f73816f5 548 Double_t pTot = 0;
5c7f4665 549 Double_t eDelta;
550 Double_t betaGamma, pp;
f73816f5 551 Double_t stepSize;
5c7f4665 552
553 TLorentzVector pos, mom;
82bbf98a 554 TClonesArray &lhits = *fHits;
555
851d3db9 556 const Double_t kBig = 1.0E+12;
5c7f4665 557
558 // Ionization energy
a3c76cdc 559 const Float_t kWion = 22.04;
560 // Maximum momentum for e+ e- g
561 const Float_t kPTotMaxEl = 0.002;
f73816f5 562 // Minimum energy for the step size adjustment
563 const Float_t kEkinMinStep = 1.0e-5;
5c7f4665 564 // Plateau value of the energy-loss for electron in xenon
565 // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
566 //const Double_t kPlateau = 1.70;
567 // the averaged value (26/3/99)
a3c76cdc 568 const Float_t kPlateau = 1.55;
5c7f4665 569 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 570 const Float_t kPrim = 48.0;
5c7f4665 571 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 572 const Float_t kPoti = 12.1;
851d3db9 573
574 // PDG code electron
8230f242 575 const Int_t kPdgElectron = 11;
5c7f4665 576
577 // Set the maximum step size to a very large number for all
578 // neutral particles and those outside the driftvolume
579 gMC->SetMaxStep(kBig);
580
581 // Use only charged tracks
582 if (( gMC->TrackCharge() ) &&
583 (!gMC->IsTrackStop() ) &&
584 (!gMC->IsTrackDisappeared())) {
fe4da5cc 585
5c7f4665 586 // Inside a sensitive volume?
82bbf98a 587 iIdSens = gMC->CurrentVolID(icSens);
f73816f5 588 if ((iIdSens == fIdSensDr) ||
589 (iIdSens == fIdSensAm)) {
82bbf98a 590
82bbf98a 591 iIdChamber = gMC->CurrentVolOffID(1,icChamber);
fe4da5cc 592
5c7f4665 593 // The hit coordinates and charge
594 gMC->TrackPosition(pos);
595 hits[0] = pos[0];
596 hits[1] = pos[1];
597 hits[2] = pos[2];
5c7f4665 598
851d3db9 599 // The sector number (0 - 17)
600 // The numbering goes clockwise and starts at y = 0
601 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
602 if (phi < 90.)
603 phi = phi + 270.;
604 else
605 phi = phi - 90.;
606 sec = ((Int_t) (phi / 20));
82bbf98a 607
d3f347ff 608 // The chamber number
851d3db9 609 // 0: outer left
610 // 1: middle left
611 // 2: inner
612 // 3: middle right
613 // 4: outer right
82bbf98a 614 if (iIdChamber == fIdChamber1)
851d3db9 615 cha = (hits[2] < 0 ? 0 : 4);
82bbf98a 616 else if (iIdChamber == fIdChamber2)
851d3db9 617 cha = (hits[2] < 0 ? 1 : 3);
82bbf98a 618 else if (iIdChamber == fIdChamber3)
851d3db9 619 cha = 2;
82bbf98a 620
fe4da5cc 621 // The plane number
851d3db9 622 // The numbering starts at the innermost plane
623 pla = icChamber - TMath::Nint((Float_t) (icChamber / 7)) * 6 - 1;
82bbf98a 624
5c7f4665 625 // Check on selected volumes
626 Int_t addthishit = 1;
627 if (fSensSelect) {
6f1e466d 628 if ((fSensPlane >= 0) && (pla != fSensPlane )) addthishit = 0;
629 if ((fSensChamber >= 0) && (cha != fSensChamber)) addthishit = 0;
9d0b222b 630 if (fSensSector >= 0) {
631 Int_t sens1 = fSensSector;
632 Int_t sens2 = fSensSector + fSensSectorRange;
793ff80c 633 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
634 * AliTRDgeometry::Nsect();
9d0b222b 635 if (sens1 < sens2) {
636 if ((sec < sens1) || (sec >= sens2)) addthishit = 0;
637 }
638 else {
639 if ((sec < sens1) && (sec >= sens2)) addthishit = 0;
640 }
641 }
5c7f4665 642 }
643
644 // Add this hit
645 if (addthishit) {
646
f73816f5 647 // The detector number
793ff80c 648 det = fGeometry->GetDetector(pla,cha,sec);
649
f73816f5 650 // Special hits and TR photons only in the drift region
651 if (iIdSens == fIdSensDr) {
652
653 // Create some special hits with amplitude 0 at the entrance and
654 // exit of each chamber that contain the momentum components of the particle
655 if (gMC->IsTrackEntering() || gMC->IsTrackExiting()) {
656 gMC->TrackMomentum(mom);
657 moms[0] = mom[0];
658 moms[1] = mom[1];
659 moms[2] = mom[2];
660 AliTRDhit *hitTest = new(lhits[fNhits++]) AliTRDhit(fIshunt
661 ,gAlice->CurrentTrack()
662 ,det,moms,0);
663 hitTest->SetTest();
664 }
665
666 // Create the hits from TR photons
667 if (fTR) CreateTRhit(det);
668
669 }
670
671 // Calculate the energy of the delta-electrons
672 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
673 eDelta = TMath::Max(eDelta,0.0);
674
675 // The number of secondary electrons created
676 qTot = ((Int_t) (eDelta / kWion) + 1);
677
678 // Create a new dEdx hit
679 AliTRDhit *hit = new(lhits[fNhits++]) AliTRDhit(fIshunt
680 ,gAlice->CurrentTrack()
681 ,det,hits,qTot);
682 if (iIdSens == fIdSensDr) {
683 hit->SetDrift();
684 }
5c7f4665 685 else {
f73816f5 686 hit->SetAmplification();
687 }
688
5c7f4665 689 // Calculate the maximum step size for the next tracking step
f73816f5 690 // Produce only one hit if Ekin is below cutoff
691 aMass = gMC->TrackMass();
692 if ((gMC->Etot() - aMass) > kEkinMinStep) {
693
694 // The energy loss according to Bethe Bloch
695 iPdg = TMath::Abs(gMC->TrackPid());
696 if ( (iPdg != kPdgElectron) ||
697 ((iPdg == kPdgElectron) && (pTot < kPTotMaxEl))) {
698 gMC->TrackMomentum(mom);
699 pTot = mom.Rho();
700 betaGamma = pTot / aMass;
701 pp = kPrim * BetheBloch(betaGamma);
702 // Take charge > 1 into account
703 charge = gMC->TrackCharge();
704 if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
705 }
706 // Electrons above 20 Mev/c are at the plateau
707 else {
708 pp = kPrim * kPlateau;
709 }
710
711 if (pp > 0) {
712 do
713 gMC->Rndm(random,1);
714 while ((random[0] == 1.) || (random[0] == 0.));
715 stepSize = - TMath::Log(random[0]) / pp;
716 gMC->SetMaxStep(stepSize);
717 }
718
5c7f4665 719 }
720
721 }
d3f347ff 722
723 }
724
5c7f4665 725 }
726
727}
728
729//_____________________________________________________________________________
730Double_t AliTRDv1::BetheBloch(Double_t bg)
731{
732 //
733 // Parametrization of the Bethe-Bloch-curve
734 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
735 //
736
737 // This parameters have been adjusted to averaged values from GEANT
738 const Double_t kP1 = 7.17960e-02;
739 const Double_t kP2 = 8.54196;
740 const Double_t kP3 = 1.38065e-06;
741 const Double_t kP4 = 5.30972;
742 const Double_t kP5 = 2.83798;
743
744 // This parameters have been adjusted to Xe-data found in:
745 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
746 //const Double_t kP1 = 0.76176E-1;
747 //const Double_t kP2 = 10.632;
748 //const Double_t kP3 = 3.17983E-6;
749 //const Double_t kP4 = 1.8631;
750 //const Double_t kP5 = 1.9479;
751
f73816f5 752 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
753 const Double_t kBgMin = 0.8;
754 const Double_t kBBMax = 6.83298;
755 //const Double_t kBgMin = 0.6;
756 //const Double_t kBBMax = 17.2809;
757 //const Double_t kBgMin = 0.4;
758 //const Double_t kBBMax = 82.0;
759
760 if (bg > kBgMin) {
5c7f4665 761 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
762 Double_t aa = TMath::Power(yy,kP4);
763 Double_t bb = TMath::Power((1./bg),kP5);
764 bb = TMath::Log(kP3 + bb);
765 return ((kP2 - aa - bb)*kP1 / aa);
766 }
f73816f5 767 else {
768 return kBBMax;
769 }
d3f347ff 770
fe4da5cc 771}
5c7f4665 772
773//_____________________________________________________________________________
774Double_t Ermilova(Double_t *x, Double_t *)
775{
776 //
777 // Calculates the delta-ray energy distribution according to Ermilova.
778 // Logarithmic scale !
779 //
780
781 Double_t energy;
782 Double_t dpos;
783 Double_t dnde;
784
785 Int_t pos1, pos2;
786
8230f242 787 const Int_t kNv = 31;
5c7f4665 788
8230f242 789 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
790 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
791 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
792 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
793 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
794 , 9.4727, 9.9035,10.3735,10.5966,10.8198
795 ,11.5129 };
5c7f4665 796
8230f242 797 Float_t vye[kNv] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
798 , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
799 , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
800 , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
801 , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
802 , 0.04 , 0.023, 0.015, 0.011, 0.01
803 , 0.004 };
5c7f4665 804
805 energy = x[0];
806
807 // Find the position
808 pos1 = pos2 = 0;
809 dpos = 0;
810 do {
811 dpos = energy - vxe[pos2++];
812 }
813 while (dpos > 0);
814 pos2--;
f73816f5 815 if (pos2 > kNv) pos2 = kNv - 1;
5c7f4665 816 pos1 = pos2 - 1;
817
818 // Differentiate between the sampling points
819 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
820
821 return dnde;
822
823}