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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/* $Id$ */
17
18///////////////////////////////////////////////////////////////////////////////
19// //
20// Transition Radiation Detector version 1 -- slow simulator //
21// //
22//Begin_Html
23/*
24<img src="picts/AliTRDfullClass.gif">
25*/
26//End_Html
27// //
28// //
29///////////////////////////////////////////////////////////////////////////////
30
31#include <stdlib.h>
32
33#include <TF1.h>
34#include <TLorentzVector.h>
35#include <TMath.h>
36#include <TRandom.h>
37#include <TVector.h>
38#include <TVirtualMC.h>
39
40#include "AliConst.h"
41#include "AliRun.h"
42#include "AliTRDgeometry.h"
43#include "AliTRDhit.h"
44#include "AliTRDsim.h"
45#include "AliTRDv1.h"
46#include "AliMC.h"
47
48ClassImp(AliTRDv1)
49
50//_____________________________________________________________________________
51AliTRDv1::AliTRDv1():AliTRD()
52{
53 //
54 // Default constructor
55 //
56
57 fSensSelect = 0;
58 fSensPlane = -1;
59 fSensChamber = -1;
60 fSensSector = -1;
61 fSensSectorRange = 0;
62
63 fDeltaE = NULL;
64 fTR = NULL;
65
66}
67
68//_____________________________________________________________________________
69AliTRDv1::AliTRDv1(const char *name, const char *title)
70 :AliTRD(name, title)
71{
72 //
73 // Standard constructor for Transition Radiation Detector version 1
74 //
75
76 fSensSelect = 0;
77 fSensPlane = -1;
78 fSensChamber = -1;
79 fSensSector = -1;
80 fSensSectorRange = 0;
81
82 fDeltaE = NULL;
83 fTR = NULL;
84
85 SetBufferSize(128000);
86
87}
88
89//_____________________________________________________________________________
90AliTRDv1::AliTRDv1(const AliTRDv1 &trd):AliTRD(trd)
91{
92 //
93 // Copy constructor
94 //
95
96 ((AliTRDv1 &) trd).Copy(*this);
97
98}
99
100//_____________________________________________________________________________
101AliTRDv1::~AliTRDv1()
102{
103 //
104 // AliTRDv1 destructor
105 //
106
107 if (fDeltaE) delete fDeltaE;
108 if (fTR) delete fTR;
109
110}
111
112//_____________________________________________________________________________
113AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
114{
115 //
116 // Assignment operator
117 //
118
119 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
120 return *this;
121
122}
123
124//_____________________________________________________________________________
125void AliTRDv1::Copy(TObject &trd)
126{
127 //
128 // Copy function
129 //
130
131 ((AliTRDv1 &) trd).fSensSelect = fSensSelect;
132 ((AliTRDv1 &) trd).fSensPlane = fSensPlane;
133 ((AliTRDv1 &) trd).fSensChamber = fSensChamber;
134 ((AliTRDv1 &) trd).fSensSector = fSensSector;
135 ((AliTRDv1 &) trd).fSensSectorRange = fSensSectorRange;
136
137 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
138 fTR->Copy(*((AliTRDv1 &) trd).fTR);
139
140}
141
142//_____________________________________________________________________________
143void AliTRDv1::CreateGeometry()
144{
145 //
146 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
147 // This version covers the full azimuth.
148 //
149
150 // Check that FRAME is there otherwise we have no place where to put the TRD
151 AliModule* frame = gAlice->GetModule("FRAME");
152 if (!frame) return;
153
154 // Define the chambers
155 AliTRD::CreateGeometry();
156
157}
158
159//_____________________________________________________________________________
160void AliTRDv1::CreateMaterials()
161{
162 //
163 // Create materials for the Transition Radiation Detector version 1
164 //
165
166 AliTRD::CreateMaterials();
167
168}
169
170//_____________________________________________________________________________
171void AliTRDv1::CreateTRhit(Int_t det)
172{
173 //
174 // Creates an electron cluster from a TR photon.
175 // The photon is assumed to be created a the end of the radiator. The
176 // distance after which it deposits its energy takes into account the
177 // absorbtion of the entrance window and of the gas mixture in drift
178 // volume.
179 //
180
181 // PDG code electron
182 const Int_t kPdgElectron = 11;
183
184 // Ionization energy
185 const Float_t kWion = 22.04;
186
187 // Maximum number of TR photons per track
188 const Int_t kNTR = 50;
189
190 TLorentzVector mom, pos;
191
192 // Create TR at the entrance of the chamber
193 if (gMC->IsTrackEntering()) {
194
195 // Create TR only for electrons
196 Int_t iPdg = gMC->TrackPid();
197 if (TMath::Abs(iPdg) != kPdgElectron) return;
198
199 Float_t eTR[kNTR];
200 Int_t nTR;
201
202 // Create TR photons
203 gMC->TrackMomentum(mom);
204 Float_t pTot = mom.Rho();
205 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
206 if (nTR > kNTR) {
207 printf("AliTRDv1::CreateTRhit -- ");
208 printf("Boundary error: nTR = %d, kNTR = %d\n",nTR,kNTR);
209 exit(1);
210 }
211
212 // Loop through the TR photons
213 for (Int_t iTR = 0; iTR < nTR; iTR++) {
214
215 Float_t energyMeV = eTR[iTR] * 0.001;
216 Float_t energyeV = eTR[iTR] * 1000.0;
217 Float_t absLength = 0;
218 Float_t sigma = 0;
219
220 // Take the absorbtion in the entrance window into account
221 Double_t muMy = fTR->GetMuMy(energyMeV);
222 sigma = muMy * fFoilDensity;
223 if (sigma > 0.0) {
224 absLength = gRandom->Exp(1.0/sigma);
225 if (absLength < AliTRDgeometry::MyThick()) continue;
226 }
227 else {
228 continue;
229 }
230
231 // The absorbtion cross sections in the drift gas
232 if (fGasMix == 1) {
233 // Gas-mixture (Xe/CO2)
234 Double_t muXe = fTR->GetMuXe(energyMeV);
235 Double_t muCO = fTR->GetMuCO(energyMeV);
236 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
237 }
238 else {
239 // Gas-mixture (Xe/Isobutane)
240 Double_t muXe = fTR->GetMuXe(energyMeV);
241 Double_t muBu = fTR->GetMuBu(energyMeV);
242 sigma = (0.97 * muXe + 0.03 * muBu) * fGasDensity * fTR->GetTemp();
243 }
244
245 // The distance after which the energy of the TR photon
246 // is deposited.
247 if (sigma > 0.0) {
248 absLength = gRandom->Exp(1.0/sigma);
249 if (absLength > AliTRDgeometry::DrThick()) continue;
250 }
251 else {
252 continue;
253 }
254
255 // The position of the absorbtion
256 Float_t posHit[3];
257 gMC->TrackPosition(pos);
258 posHit[0] = pos[0] + mom[0] / pTot * absLength;
259 posHit[1] = pos[1] + mom[1] / pTot * absLength;
260 posHit[2] = pos[2] + mom[2] / pTot * absLength;
261
262 // Create the charge
263 Int_t q = ((Int_t) (energyeV / kWion));
264
265 // Add the hit to the array. TR photon hits are marked
266 // by negative charge
267 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber(),det,posHit,-q,kTRUE);
268
269 }
270
271 }
272
273}
274
275//_____________________________________________________________________________
276void AliTRDv1::Init()
277{
278 //
279 // Initialise Transition Radiation Detector after geometry has been built.
280 //
281
282 AliTRD::Init();
283
284 if(fDebug) printf("%s: Slow simulator\n",ClassName());
285 if (fSensSelect) {
286 if (fSensPlane >= 0)
287 printf(" Only plane %d is sensitive\n",fSensPlane);
288 if (fSensChamber >= 0)
289 printf(" Only chamber %d is sensitive\n",fSensChamber);
290 if (fSensSector >= 0) {
291 Int_t sens1 = fSensSector;
292 Int_t sens2 = fSensSector + fSensSectorRange;
293 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
294 * AliTRDgeometry::Nsect();
295 printf(" Only sectors %d - %d are sensitive\n",sens1,sens2-1);
296 }
297 }
298 if (fTR)
299 printf("%s: TR simulation on\n",ClassName());
300 else
301 printf("%s: TR simulation off\n",ClassName());
302 printf("\n");
303
304 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
305 const Float_t kPoti = 12.1;
306 // Maximum energy (50 keV);
307 const Float_t kEend = 50000.0;
308 // Ermilova distribution for the delta-ray spectrum
309 Float_t poti = TMath::Log(kPoti);
310 Float_t eEnd = TMath::Log(kEend);
311 fDeltaE = new TF1("deltae",Ermilova,poti,eEnd,0);
312
313 if(fDebug) {
314 printf("%s: ",ClassName());
315 for (Int_t i = 0; i < 80; i++) printf("*");
316 printf("\n");
317 }
318
319}
320
321//_____________________________________________________________________________
322AliTRDsim *AliTRDv1::CreateTR()
323{
324 //
325 // Enables the simulation of TR
326 //
327
328 fTR = new AliTRDsim();
329 return fTR;
330
331}
332
333//_____________________________________________________________________________
334void AliTRDv1::SetSensPlane(Int_t iplane)
335{
336 //
337 // Defines the hit-sensitive plane (0-5)
338 //
339
340 if ((iplane < 0) || (iplane > 5)) {
341 printf("Wrong input value: %d\n",iplane);
342 printf("Use standard setting\n");
343 fSensPlane = -1;
344 fSensSelect = 0;
345 return;
346 }
347
348 fSensSelect = 1;
349 fSensPlane = iplane;
350
351}
352
353//_____________________________________________________________________________
354void AliTRDv1::SetSensChamber(Int_t ichamber)
355{
356 //
357 // Defines the hit-sensitive chamber (0-4)
358 //
359
360 if ((ichamber < 0) || (ichamber > 4)) {
361 printf("Wrong input value: %d\n",ichamber);
362 printf("Use standard setting\n");
363 fSensChamber = -1;
364 fSensSelect = 0;
365 return;
366 }
367
368 fSensSelect = 1;
369 fSensChamber = ichamber;
370
371}
372
373//_____________________________________________________________________________
374void AliTRDv1::SetSensSector(Int_t isector)
375{
376 //
377 // Defines the hit-sensitive sector (0-17)
378 //
379
380 SetSensSector(isector,1);
381
382}
383
384//_____________________________________________________________________________
385void AliTRDv1::SetSensSector(Int_t isector, Int_t nsector)
386{
387 //
388 // Defines a range of hit-sensitive sectors. The range is defined by
389 // <isector> (0-17) as the starting point and <nsector> as the number
390 // of sectors to be included.
391 //
392
393 if ((isector < 0) || (isector > 17)) {
394 printf("Wrong input value <isector>: %d\n",isector);
395 printf("Use standard setting\n");
396 fSensSector = -1;
397 fSensSectorRange = 0;
398 fSensSelect = 0;
399 return;
400 }
401
402 if ((nsector < 1) || (nsector > 18)) {
403 printf("Wrong input value <nsector>: %d\n",nsector);
404 printf("Use standard setting\n");
405 fSensSector = -1;
406 fSensSectorRange = 0;
407 fSensSelect = 0;
408 return;
409 }
410
411 fSensSelect = 1;
412 fSensSector = isector;
413 fSensSectorRange = nsector;
414
415}
416
417//_____________________________________________________________________________
418void AliTRDv1::StepManager()
419{
420 //
421 // Slow simulator. Every charged track produces electron cluster as hits
422 // along its path across the drift volume. The step size is set acording
423 // to Bethe-Bloch. The energy distribution of the delta electrons follows
424 // a spectrum taken from Ermilova et al.
425 //
426
427 Int_t pla = 0;
428 Int_t cha = 0;
429 Int_t sec = 0;
430 Int_t det = 0;
431 Int_t iPdg;
432 Int_t qTot;
433
434 Float_t hits[3];
435 Double_t random[1];
436 Float_t charge;
437 Float_t aMass;
438
439 Double_t pTot = 0;
440 Double_t eDelta;
441 Double_t betaGamma, pp;
442 Double_t stepSize;
443
444 Bool_t drRegion = kFALSE;
445 Bool_t amRegion = kFALSE;
446
447 TString cIdCurrent;
448 TString cIdSensDr = "J";
449 TString cIdSensAm = "K";
450 Char_t cIdChamber[3];
451 cIdChamber[2] = 0;
452
453 TLorentzVector pos, mom;
454
455 const Int_t kNplan = AliTRDgeometry::Nplan();
456 const Int_t kNcham = AliTRDgeometry::Ncham();
457 const Int_t kNdetsec = kNplan * kNcham;
458
459 const Double_t kBig = 1.0E+12;
460
461 // Ionization energy
462 const Float_t kWion = 22.04;
463 // Maximum momentum for e+ e- g
464 const Float_t kPTotMaxEl = 0.002;
465 // Minimum energy for the step size adjustment
466 const Float_t kEkinMinStep = 1.0e-5;
467 // Plateau value of the energy-loss for electron in xenon
468 // taken from: Allison + Comb, Ann. Rev. Nucl. Sci. (1980), 30, 253
469 //const Double_t kPlateau = 1.70;
470 // the averaged value (26/3/99)
471 const Float_t kPlateau = 1.55;
472 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
473 const Float_t kPrim = 48.0;
474 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
475 const Float_t kPoti = 12.1;
476
477 // PDG code electron
478 const Int_t kPdgElectron = 11;
479
480 // Set the maximum step size to a very large number for all
481 // neutral particles and those outside the driftvolume
482 gMC->SetMaxStep(kBig);
483
484 // Use only charged tracks
485 if (( gMC->TrackCharge() ) &&
486 (!gMC->IsTrackStop() ) &&
487 (!gMC->IsTrackDisappeared())) {
488
489 // Inside a sensitive volume?
490 drRegion = kFALSE;
491 amRegion = kFALSE;
492 cIdCurrent = gMC->CurrentVolName();
493 if (cIdSensDr == cIdCurrent[1]) {
494 drRegion = kTRUE;
495 }
496 if (cIdSensAm == cIdCurrent[1]) {
497 amRegion = kTRUE;
498 }
499 if (drRegion || amRegion) {
500
501 // The hit coordinates and charge
502 gMC->TrackPosition(pos);
503 hits[0] = pos[0];
504 hits[1] = pos[1];
505 hits[2] = pos[2];
506
507 // The sector number (0 - 17)
508 // The numbering goes clockwise and starts at y = 0
509 // Not fully consistent to new corrdinate schema!!!
510 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
511 if (phi < 90.)
512 phi = phi + 270.;
513 else
514 phi = phi - 90.;
515 sec = ((Int_t) (phi / 20));
516
517 // The plane and chamber number
518 cIdChamber[0] = cIdCurrent[2];
519 cIdChamber[1] = cIdCurrent[3];
520 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
521 cha = ((Int_t) idChamber / kNplan);
522 pla = ((Int_t) idChamber % kNplan);
523
524 // Check on selected volumes
525 Int_t addthishit = 1;
526 if (fSensSelect) {
527 if ((fSensPlane >= 0) && (pla != fSensPlane )) addthishit = 0;
528 if ((fSensChamber >= 0) && (cha != fSensChamber)) addthishit = 0;
529 if (fSensSector >= 0) {
530 Int_t sens1 = fSensSector;
531 Int_t sens2 = fSensSector + fSensSectorRange;
532 sens2 -= ((Int_t) (sens2 / AliTRDgeometry::Nsect()))
533 * AliTRDgeometry::Nsect();
534 if (sens1 < sens2) {
535 if ((sec < sens1) || (sec >= sens2)) addthishit = 0;
536 }
537 else {
538 if ((sec < sens1) && (sec >= sens2)) addthishit = 0;
539 }
540 }
541 }
542
543 // Add this hit
544 if (addthishit) {
545
546 // The detector number
547 det = fGeometry->GetDetector(pla,cha,sec);
548
549 // Special hits and TR photons only in the drift region
550 if (drRegion) {
551
552 // Create a track reference at the entrance and
553 // exit of each chamber that contain the
554 // momentum components of the particle
555 if (gMC->IsTrackEntering() || gMC->IsTrackExiting()) {
556 gMC->TrackMomentum(mom);
557 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
558 }
559
560 // Create the hits from TR photons
561 if (fTR) CreateTRhit(det);
562
563 }
564
565 // Calculate the energy of the delta-electrons
566 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
567 eDelta = TMath::Max(eDelta,0.0);
568
569 // The number of secondary electrons created
570 qTot = ((Int_t) (eDelta / kWion) + 1);
571
572 // Create a new dEdx hit
573 if (drRegion) {
574 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber(),det,hits,qTot,kTRUE);
575 }
576 else {
577 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber(),det,hits,qTot,kFALSE);
578 }
579
580 // Calculate the maximum step size for the next tracking step
581 // Produce only one hit if Ekin is below cutoff
582 aMass = gMC->TrackMass();
583 if ((gMC->Etot() - aMass) > kEkinMinStep) {
584
585 // The energy loss according to Bethe Bloch
586 iPdg = TMath::Abs(gMC->TrackPid());
587 if ( (iPdg != kPdgElectron) ||
588 ((iPdg == kPdgElectron) && (pTot < kPTotMaxEl))) {
589 gMC->TrackMomentum(mom);
590 pTot = mom.Rho();
591 betaGamma = pTot / aMass;
592 pp = kPrim * BetheBloch(betaGamma);
593 // Take charge > 1 into account
594 charge = gMC->TrackCharge();
595 if (TMath::Abs(charge) > 1) pp = pp * charge*charge;
596 }
597 // Electrons above 20 Mev/c are at the plateau
598 else {
599 pp = kPrim * kPlateau;
600 }
601
602 if (pp > 0) {
603 do
604 gMC->GetRandom()->RndmArray(1, random);
605 while ((random[0] == 1.) || (random[0] == 0.));
606 stepSize = - TMath::Log(random[0]) / pp;
607 gMC->SetMaxStep(stepSize);
608 }
609
610 }
611
612 }
613
614 }
615
616 }
617
618}
619
620//_____________________________________________________________________________
621Double_t AliTRDv1::BetheBloch(Double_t bg)
622{
623 //
624 // Parametrization of the Bethe-Bloch-curve
625 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
626 //
627
628 // This parameters have been adjusted to averaged values from GEANT
629 const Double_t kP1 = 7.17960e-02;
630 const Double_t kP2 = 8.54196;
631 const Double_t kP3 = 1.38065e-06;
632 const Double_t kP4 = 5.30972;
633 const Double_t kP5 = 2.83798;
634
635 // This parameters have been adjusted to Xe-data found in:
636 // Allison & Cobb, Ann. Rev. Nucl. Sci. (1980), 30, 253
637 //const Double_t kP1 = 0.76176E-1;
638 //const Double_t kP2 = 10.632;
639 //const Double_t kP3 = 3.17983E-6;
640 //const Double_t kP4 = 1.8631;
641 //const Double_t kP5 = 1.9479;
642
643 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
644 const Double_t kBgMin = 0.8;
645 const Double_t kBBMax = 6.83298;
646 //const Double_t kBgMin = 0.6;
647 //const Double_t kBBMax = 17.2809;
648 //const Double_t kBgMin = 0.4;
649 //const Double_t kBBMax = 82.0;
650
651 if (bg > kBgMin) {
652 Double_t yy = bg / TMath::Sqrt(1. + bg*bg);
653 Double_t aa = TMath::Power(yy,kP4);
654 Double_t bb = TMath::Power((1./bg),kP5);
655 bb = TMath::Log(kP3 + bb);
656 return ((kP2 - aa - bb)*kP1 / aa);
657 }
658 else {
659 return kBBMax;
660 }
661
662}
663
664//_____________________________________________________________________________
665Double_t Ermilova(Double_t *x, Double_t *)
666{
667 //
668 // Calculates the delta-ray energy distribution according to Ermilova.
669 // Logarithmic scale !
670 //
671
672 Double_t energy;
673 Double_t dpos;
674 Double_t dnde;
675
676 Int_t pos1, pos2;
677
678 const Int_t kNv = 31;
679
680 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
681 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
682 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
683 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
684 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
685 , 9.4727, 9.9035,10.3735,10.5966,10.8198
686 ,11.5129 };
687
688 Float_t vye[kNv] = { 80.0 , 31.0 , 23.3 , 21.1 , 21.0
689 , 20.9 , 20.8 , 20.0 , 16.0 , 11.0
690 , 8.0 , 6.0 , 5.2 , 4.6 , 4.0
691 , 3.5 , 3.0 , 1.4 , 0.67 , 0.44
692 , 0.3 , 0.18 , 0.12 , 0.08 , 0.056
693 , 0.04 , 0.023, 0.015, 0.011, 0.01
694 , 0.004 };
695
696 energy = x[0];
697
698 // Find the position
699 pos1 = pos2 = 0;
700 dpos = 0;
701 do {
702 dpos = energy - vxe[pos2++];
703 }
704 while (dpos > 0);
705 pos2--;
706 if (pos2 > kNv) pos2 = kNv - 1;
707 pos1 = pos2 - 1;
708
709 // Differentiate between the sampling points
710 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
711
712 return dnde;
713
714}