Remove kX0shift5 since all planes are now equal
[u/mrichter/AliRoot.git] / TRD / AliTRDv1.cxx
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4c039060 1/**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
3 * *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
6 * *
7 * Permission to use, copy, modify and distribute this software and its *
8 * documentation strictly for non-commercial purposes is hereby granted *
9 * without fee, provided that the above copyright notice appears in all *
10 * copies and that both the copyright notice and this permission notice *
11 * appear in the supporting documentation. The authors make no claims *
12 * about the suitability of this software for any purpose. It is *
13 * provided "as is" without express or implied warranty. *
14 **************************************************************************/
15
88cb7938 16/* $Id$ */
4c039060 17
030b4415 18////////////////////////////////////////////////////////////////////////////
19// //
20// Transition Radiation Detector version 1 -- slow simulator //
21// //
22////////////////////////////////////////////////////////////////////////////
fe4da5cc 23
769257f4 24#include <stdlib.h>
25
793ff80c 26#include <TF1.h>
1819f4bb 27#include <TLorentzVector.h>
88cb7938 28#include <TMath.h>
29#include <TRandom.h>
30#include <TVector.h>
31#include <TVirtualMC.h>
f57bb418 32#include <TGeoManager.h>
fe4da5cc 33
d3f347ff 34#include "AliConst.h"
45160b1f 35#include "AliLog.h"
36#include "AliMC.h"
88cb7938 37#include "AliRun.h"
030b4415 38
88cb7938 39#include "AliTRDgeometry.h"
793ff80c 40#include "AliTRDhit.h"
793ff80c 41#include "AliTRDsim.h"
88cb7938 42#include "AliTRDv1.h"
851d3db9 43
fe4da5cc 44ClassImp(AliTRDv1)
8230f242 45
46//_____________________________________________________________________________
030b4415 47AliTRDv1::AliTRDv1()
48 :AliTRD()
49 ,fTRon(kFALSE)
50 ,fTR(NULL)
51 ,fTypeOfStepManager(0)
52 ,fStepSize(0)
53 ,fDeltaE(NULL)
54 ,fDeltaG(NULL)
55 ,fTrackLength0(0)
56 ,fPrimaryTrackPid(0)
8230f242 57{
58 //
59 // Default constructor
60 //
61
8230f242 62}
63
fe4da5cc 64//_____________________________________________________________________________
65AliTRDv1::AliTRDv1(const char *name, const char *title)
030b4415 66 :AliTRD(name,title)
67 ,fTRon(kTRUE)
68 ,fTR(NULL)
67c47633 69 ,fTypeOfStepManager(2)
030b4415 70 ,fStepSize(0.1)
71 ,fDeltaE(NULL)
72 ,fDeltaG(NULL)
73 ,fTrackLength0(0)
74 ,fPrimaryTrackPid(0)
fe4da5cc 75{
76 //
851d3db9 77 // Standard constructor for Transition Radiation Detector version 1
fe4da5cc 78 //
82bbf98a 79
5c7f4665 80 SetBufferSize(128000);
81
82}
83
84//_____________________________________________________________________________
85AliTRDv1::~AliTRDv1()
86{
dd9a6ee3 87 //
88 // AliTRDv1 destructor
89 //
82bbf98a 90
030b4415 91 if (fDeltaE) {
92 delete fDeltaE;
93 fDeltaE = 0;
94 }
95
96 if (fDeltaG) {
97 delete fDeltaG;
98 fDeltaG = 0;
99 }
100
101 if (fTR) {
102 delete fTR;
103 fTR = 0;
104 }
82bbf98a 105
fe4da5cc 106}
107
dd9a6ee3 108//_____________________________________________________________________________
f57bb418 109void AliTRDv1::AddAlignableVolumes() const
110{
111 //
112 // Create entries for alignable volumes associating the symbolic volume
113 // name with the corresponding volume path. Needs to be syncronized with
114 // eventual changes in the geometry.
115 //
116
117 TString volPath;
118 TString symName;
119
120 TString vpStr = "ALIC_1/B077_1/BSEGMO";
121 TString vpApp1 = "_1/BTRD";
122 TString vpApp2 = "_1";
123 TString vpApp3 = "/UTR1_1/UTS1_1/UTI1_1/UT";
124
125 TString snStr = "TRD/sm";
126 TString snApp1 = "/st";
127 TString snApp2 = "/pl";
128
129 //
130 // The super modules
131 // The symbolic names are: TRD/sm00
132 // ...
133 // TRD/sm17
134 //
135 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
136
137 volPath = vpStr;
138 volPath += isect;
139 volPath += vpApp1;
140 volPath += isect;
141 volPath += vpApp2;
142
143 symName = snStr;
144 symName += Form("%02d",isect);
145
146 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
147
148 }
149
150 //
151 // The readout chambers
152 // The symbolic names are: TRD/sm00/st0/pl0
153 // ...
154 // TRD/sm17/st4/pl5
155 //
156 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
157 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
158 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
159
160 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
161
162 volPath = vpStr;
163 volPath += isect;
164 volPath += vpApp1;
165 volPath += isect;
166 volPath += vpApp2;
167 volPath += vpApp3;
168 volPath += Form("%02d",idet);
169 volPath += vpApp2;
170
171 symName = snStr;
172 symName += Form("%02d",isect);
173 symName += snApp1;
174 symName += icham;
175 symName += snApp2;
176 symName += iplan;
177
f57bb418 178 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
179
180 }
181 }
182 }
183
184}
185
186//_____________________________________________________________________________
fe4da5cc 187void AliTRDv1::CreateGeometry()
188{
189 //
851d3db9 190 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 191 // This version covers the full azimuth.
d3f347ff 192 //
193
82bbf98a 194 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 195 AliModule* frame = gAlice->GetModule("FRAME");
030b4415 196 if (!frame) {
197 AliError("TRD needs FRAME to be present\n");
198 return;
199 }
d3f347ff 200
82bbf98a 201 // Define the chambers
202 AliTRD::CreateGeometry();
d3f347ff 203
fe4da5cc 204}
205
206//_____________________________________________________________________________
207void AliTRDv1::CreateMaterials()
208{
209 //
851d3db9 210 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 211 //
82bbf98a 212
d3f347ff 213 AliTRD::CreateMaterials();
82bbf98a 214
fe4da5cc 215}
216
217//_____________________________________________________________________________
793ff80c 218void AliTRDv1::CreateTRhit(Int_t det)
219{
220 //
221 // Creates an electron cluster from a TR photon.
222 // The photon is assumed to be created a the end of the radiator. The
223 // distance after which it deposits its energy takes into account the
224 // absorbtion of the entrance window and of the gas mixture in drift
225 // volume.
226 //
227
793ff80c 228 // Ionization energy
bc327ce2 229 const Float_t kWion = 23.53;
793ff80c 230
231 // Maximum number of TR photons per track
232 const Int_t kNTR = 50;
233
030b4415 234 TLorentzVector mom;
235 TLorentzVector pos;
793ff80c 236
ce0d6231 237 Float_t eTR[kNTR];
238 Int_t nTR;
793ff80c 239
ce0d6231 240 // Create TR photons
241 gMC->TrackMomentum(mom);
242 Float_t pTot = mom.Rho();
243 fTR->CreatePhotons(11,pTot,nTR,eTR);
244 if (nTR > kNTR) {
245 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
246 }
f73816f5 247
ce0d6231 248 // Loop through the TR photons
249 for (Int_t iTR = 0; iTR < nTR; iTR++) {
793ff80c 250
ce0d6231 251 Float_t energyMeV = eTR[iTR] * 0.001;
252 Float_t energyeV = eTR[iTR] * 1000.0;
253 Float_t absLength = 0.0;
254 Float_t sigma = 0.0;
793ff80c 255
ce0d6231 256 // Take the absorbtion in the entrance window into account
257 Double_t muMy = fTR->GetMuMy(energyMeV);
258 sigma = muMy * fFoilDensity;
259 if (sigma > 0.0) {
260 absLength = gRandom->Exp(1.0/sigma);
261 if (absLength < AliTRDgeometry::MyThick()) {
842287f2 262 continue;
263 }
ce0d6231 264 }
265 else {
266 continue;
267 }
793ff80c 268
ce0d6231 269 // The absorbtion cross sections in the drift gas
270 // Gas-mixture (Xe/CO2)
271 Double_t muXe = fTR->GetMuXe(energyMeV);
272 Double_t muCO = fTR->GetMuCO(energyMeV);
273 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
274
275 // The distance after which the energy of the TR photon
276 // is deposited.
277 if (sigma > 0.0) {
278 absLength = gRandom->Exp(1.0/sigma);
279 if (absLength > (AliTRDgeometry::DrThick()
280 + AliTRDgeometry::AmThick())) {
842287f2 281 continue;
282 }
ce0d6231 283 }
284 else {
285 continue;
286 }
793ff80c 287
ce0d6231 288 // The position of the absorbtion
289 Float_t posHit[3];
290 gMC->TrackPosition(pos);
291 posHit[0] = pos[0] + mom[0] / pTot * absLength;
292 posHit[1] = pos[1] + mom[1] / pTot * absLength;
293 posHit[2] = pos[2] + mom[2] / pTot * absLength;
793ff80c 294
ce0d6231 295 // Create the charge
296 Int_t q = ((Int_t) (energyeV / kWion));
793ff80c 297
ce0d6231 298 // Add the hit to the array. TR photon hits are marked
299 // by negative charge
300 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
301 ,det
302 ,posHit
303 ,-q
25ca55ce 304 ,gMC->TrackTime()*1.0e06
d4c6453d 305 ,kTRUE);
793ff80c 306
307 }
308
309}
310
311//_____________________________________________________________________________
5c7f4665 312void AliTRDv1::Init()
313{
314 //
315 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 316 //
317
318 AliTRD::Init();
319
45160b1f 320 AliDebug(1,"Slow simulator\n");
bd0f8685 321
322 // Switch on TR simulation as default
323 if (!fTRon) {
45160b1f 324 AliInfo("TR simulation off");
bd0f8685 325 }
326 else {
327 fTR = new AliTRDsim();
328 }
5c7f4665 329
330 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
331 const Float_t kPoti = 12.1;
332 // Maximum energy (50 keV);
333 const Float_t kEend = 50000.0;
334 // Ermilova distribution for the delta-ray spectrum
030b4415 335 Float_t poti = TMath::Log(kPoti);
336 Float_t eEnd = TMath::Log(kEend);
a328fff9 337
338 // Ermilova distribution for the delta-ray spectrum
c4214bc0 339 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
a328fff9 340
341 // Geant3 distribution for the delta-ray spectrum
c4214bc0 342 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
5c7f4665 343
45160b1f 344 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
5c7f4665 345
fe4da5cc 346}
347
348//_____________________________________________________________________________
5c7f4665 349void AliTRDv1::StepManager()
350{
351 //
c4214bc0 352 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 353 // along its path across the drift volume.
354 //
355
356 switch (fTypeOfStepManager) {
a6dd11e9 357 case 0:
358 StepManagerErmilova();
359 break;
360 case 1:
361 StepManagerGeant();
362 break;
363 case 2:
364 StepManagerFixedStep();
365 break;
366 default:
367 AliWarning("Not a valid Step Manager.");
a328fff9 368 }
369
370}
371
372//_____________________________________________________________________________
373void AliTRDv1::SelectStepManager(Int_t t)
374{
375 //
376 // Selects a step manager type:
377 // 0 - Ermilova
378 // 1 - Geant3
379 // 2 - Fixed step size
380 //
381
a328fff9 382 fTypeOfStepManager = t;
45160b1f 383 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
a328fff9 384
385}
386
387//_____________________________________________________________________________
388void AliTRDv1::StepManagerGeant()
389{
390 //
c4214bc0 391 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 392 // along its path across the drift volume. The step size is set acording
393 // to Bethe-Bloch. The energy distribution of the delta electrons follows
394 // a spectrum taken from Geant3.
395 //
f2e3a0b5 396 // Version by A. Bercuci
397 //
398
c4214bc0 399 Int_t pla = 0;
400 Int_t cha = 0;
401 Int_t sec = 0;
402 Int_t det = 0;
403 Int_t iPdg;
404 Int_t qTot;
405
406 Float_t hits[3];
407 Float_t charge;
408 Float_t aMass;
409
030b4415 410 Double_t pTot = 0;
c4214bc0 411 Double_t eDelta;
030b4415 412 Double_t betaGamma;
413 Double_t pp;
f2e3a0b5 414 Double_t stepSize = 0;
c4214bc0 415
416 Bool_t drRegion = kFALSE;
417 Bool_t amRegion = kFALSE;
418
2c8bf4aa 419 TString cIdPath;
420 Char_t cIdSector[3];
421 cIdSector[2] = 0;
422
c4214bc0 423 TString cIdCurrent;
424 TString cIdSensDr = "J";
425 TString cIdSensAm = "K";
426 Char_t cIdChamber[3];
427 cIdChamber[2] = 0;
428
030b4415 429 TLorentzVector pos;
430 TLorentzVector mom;
c4214bc0 431
030b4415 432 TArrayI processes;
f2e3a0b5 433
c4214bc0 434 const Int_t kNplan = AliTRDgeometry::Nplan();
435 const Int_t kNcham = AliTRDgeometry::Ncham();
436 const Int_t kNdetsec = kNplan * kNcham;
437
030b4415 438 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 439 const Float_t kWion = 23.53; // Ionization energy
c4214bc0 440 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
441
442 // Minimum energy for the step size adjustment
443 const Float_t kEkinMinStep = 1.0e-5;
444 // energy threshold for production of delta electrons
f2e3a0b5 445 const Float_t kECut = 1.0e4;
446 // Parameters entering the parametrized range for delta electrons
030b4415 447 const Float_t kRa = 5.37e-4;
f2e3a0b5 448 const Float_t kRb = 0.9815;
030b4415 449 const Float_t kRc = 3.123e-3;
f2e3a0b5 450 // Gas density -> To be made user adjustable !
030b4415 451 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
452 const Float_t kRho = 0.004945 ;
a328fff9 453
c4214bc0 454 // Plateau value of the energy-loss for electron in xenon
030b4415 455 // The averaged value (26/3/99)
c4214bc0 456 const Float_t kPlateau = 1.55;
030b4415 457 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
458 const Float_t kPrim = 19.34;
c4214bc0 459 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
460 const Float_t kPoti = 12.1;
030b4415 461 // PDG code electron
462 const Int_t kPdgElectron = 11;
c4214bc0 463
464 // Set the maximum step size to a very large number for all
465 // neutral particles and those outside the driftvolume
466 gMC->SetMaxStep(kBig);
467
468 // Use only charged tracks
469 if (( gMC->TrackCharge() ) &&
c4214bc0 470 (!gMC->IsTrackDisappeared())) {
471
472 // Inside a sensitive volume?
473 drRegion = kFALSE;
474 amRegion = kFALSE;
475 cIdCurrent = gMC->CurrentVolName();
476 if (cIdSensDr == cIdCurrent[1]) {
477 drRegion = kTRUE;
478 }
479 if (cIdSensAm == cIdCurrent[1]) {
480 amRegion = kTRUE;
481 }
482 if (drRegion || amRegion) {
a328fff9 483
c4214bc0 484 // The hit coordinates and charge
485 gMC->TrackPosition(pos);
486 hits[0] = pos[0];
487 hits[1] = pos[1];
488 hits[2] = pos[2];
489
2c8bf4aa 490 // The sector number (0 - 17), according to standard coordinate system
491 cIdPath = gGeoManager->GetPath();
492 cIdSector[0] = cIdPath[21];
493 cIdSector[1] = cIdPath[22];
494 sec = atoi(cIdSector);
c4214bc0 495
496 // The plane and chamber number
030b4415 497 cIdChamber[0] = cIdCurrent[2];
498 cIdChamber[1] = cIdCurrent[3];
c4214bc0 499 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 500 cha = ((Int_t) idChamber / kNplan);
c4214bc0 501 pla = ((Int_t) idChamber % kNplan);
502
ce0d6231 503 // The detector number
504 det = fGeometry->GetDetector(pla,cha,sec);
c4214bc0 505
ce0d6231 506 // Special hits only in the drift region
507 if ((drRegion) &&
508 (gMC->IsTrackEntering())) {
c4214bc0 509
ce0d6231 510 // Create a track reference at the entrance of each
511 // chamber that contains the momentum components of the particle
512 gMC->TrackMomentum(mom);
513 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
c4214bc0 514
ce0d6231 515 // Create the hits from TR photons if electron/positron is
516 // entering the drift volume
517 if ((fTR) &&
518 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
519 CreateTRhit(det);
520 }
f2e3a0b5 521
ce0d6231 522 }
523 else if ((amRegion) &&
524 (gMC->IsTrackExiting())) {
f2e3a0b5 525
ce0d6231 526 // Create a track reference at the exit of each
527 // chamber that contains the momentum components of the particle
528 gMC->TrackMomentum(mom);
529 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
c4214bc0 530
ce0d6231 531 }
c4214bc0 532
ce0d6231 533 // Calculate the energy of the delta-electrons
534 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
535 // take into account correlation with the underlying GEANT tracking
536 // mechanism. see
537 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
538 //
539 // determine the most significant process (last on the processes list)
540 // which caused this hit
541 gMC->StepProcesses(processes);
542 Int_t nofprocesses = processes.GetSize();
543 Int_t pid;
544 if (!nofprocesses) {
545 pid = 0;
546 }
547 else {
548 pid = processes[nofprocesses-1];
549 }
f2e3a0b5 550
ce0d6231 551 // Generate Edep according to GEANT parametrisation
552 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
553 eDelta = TMath::Max(eDelta,0.0);
554 Float_t prRange = 0.0;
555 Float_t range = gMC->TrackLength() - fTrackLength0;
556 // merge GEANT tracker information with locally cooked one
557 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
558 if (pid == 27) {
559 if (eDelta >= kECut) {
560 prRange = kRa * eDelta * 0.001
561 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
562 if (prRange >= (3.7 - range)) {
563 eDelta *= 0.1;
564 }
565 }
566 }
567 else if (pid == 1) {
568 if (eDelta < kECut) {
569 eDelta *= 0.5;
570 }
571 else {
572 prRange = kRa * eDelta * 0.001
573 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
574 if (prRange >= ((AliTRDgeometry::DrThick()
575 + AliTRDgeometry::AmThick()) - range)) {
576 eDelta *= 0.05;
577 }
578 else {
f2e3a0b5 579 eDelta *= 0.5;
ce0d6231 580 }
581 }
582 }
f2e3a0b5 583 else {
584 eDelta = 0.0;
ce0d6231 585 }
586 }
587 else {
588 eDelta = 0.0;
589 }
c4214bc0 590
ce0d6231 591 // Generate the electron cluster size
592 if (eDelta > 0.0) {
f2e3a0b5 593
ce0d6231 594 qTot = ((Int_t) (eDelta / kWion) + 1);
595
596 // Create a new dEdx hit
030b4415 597 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
598 ,det
599 ,hits
600 ,qTot
25ca55ce 601 ,gMC->TrackTime()*1.0e06
030b4415 602 ,drRegion);
c4214bc0 603
ce0d6231 604 }
605
606 // Calculate the maximum step size for the next tracking step
607 // Produce only one hit if Ekin is below cutoff
608 aMass = gMC->TrackMass();
609 if ((gMC->Etot() - aMass) > kEkinMinStep) {
610
611 // The energy loss according to Bethe Bloch
612 iPdg = TMath::Abs(gMC->TrackPid());
613 if ((iPdg != kPdgElectron) ||
614 ((iPdg == kPdgElectron) &&
615 (pTot < kPTotMaxEl))) {
616 gMC->TrackMomentum(mom);
617 pTot = mom.Rho();
618 betaGamma = pTot / aMass;
619 pp = BetheBlochGeant(betaGamma);
620 // Take charge > 1 into account
621 charge = gMC->TrackCharge();
622 if (TMath::Abs(charge) > 1) {
623 pp = pp * charge*charge;
624 }
625 }
626 else {
627 // Electrons above 20 Mev/c are at the plateau
628 pp = kPrim * kPlateau;
629 }
f2e3a0b5 630
ce0d6231 631 Int_t nsteps = 0;
632 do {
633 nsteps = gRandom->Poisson(pp);
634 } while(!nsteps);
635 stepSize = 1.0 / nsteps;
636 gMC->SetMaxStep(stepSize);
f2e3a0b5 637
c4214bc0 638 }
f2e3a0b5 639
c4214bc0 640 }
f2e3a0b5 641
c4214bc0 642 }
f2e3a0b5 643
a328fff9 644}
645
646//_____________________________________________________________________________
647void AliTRDv1::StepManagerErmilova()
648{
649 //
650 // Slow simulator. Every charged track produces electron cluster as hits
5c7f4665 651 // along its path across the drift volume. The step size is set acording
652 // to Bethe-Bloch. The energy distribution of the delta electrons follows
653 // a spectrum taken from Ermilova et al.
654 //
655
851d3db9 656 Int_t pla = 0;
657 Int_t cha = 0;
658 Int_t sec = 0;
793ff80c 659 Int_t det = 0;
851d3db9 660 Int_t iPdg;
793ff80c 661 Int_t qTot;
5c7f4665 662
793ff80c 663 Float_t hits[3];
a5cadd36 664 Double_t random[1];
5c7f4665 665 Float_t charge;
666 Float_t aMass;
667
030b4415 668 Double_t pTot = 0.0;
5c7f4665 669 Double_t eDelta;
030b4415 670 Double_t betaGamma;
671 Double_t pp;
f73816f5 672 Double_t stepSize;
5c7f4665 673
332e9569 674 Bool_t drRegion = kFALSE;
675 Bool_t amRegion = kFALSE;
676
2c8bf4aa 677 TString cIdPath;
678 Char_t cIdSector[3];
679 cIdSector[2] = 0;
680
332e9569 681 TString cIdCurrent;
682 TString cIdSensDr = "J";
683 TString cIdSensAm = "K";
593a9fc3 684 Char_t cIdChamber[3];
685 cIdChamber[2] = 0;
332e9569 686
030b4415 687 TLorentzVector pos;
688 TLorentzVector mom;
82bbf98a 689
332e9569 690 const Int_t kNplan = AliTRDgeometry::Nplan();
e644678a 691 const Int_t kNcham = AliTRDgeometry::Ncham();
692 const Int_t kNdetsec = kNplan * kNcham;
693
030b4415 694 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 695 const Float_t kWion = 23.53; // Ionization energy
a328fff9 696 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
5c7f4665 697
f73816f5 698 // Minimum energy for the step size adjustment
699 const Float_t kEkinMinStep = 1.0e-5;
a328fff9 700
5c7f4665 701 // Plateau value of the energy-loss for electron in xenon
030b4415 702 // The averaged value (26/3/99)
a3c76cdc 703 const Float_t kPlateau = 1.55;
030b4415 704 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
705 const Float_t kPrim = 48.0;
5c7f4665 706 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 707 const Float_t kPoti = 12.1;
030b4415 708 // PDG code electron
709 const Int_t kPdgElectron = 11;
5c7f4665 710
711 // Set the maximum step size to a very large number for all
712 // neutral particles and those outside the driftvolume
713 gMC->SetMaxStep(kBig);
714
715 // Use only charged tracks
716 if (( gMC->TrackCharge() ) &&
5c7f4665 717 (!gMC->IsTrackDisappeared())) {
fe4da5cc 718
5c7f4665 719 // Inside a sensitive volume?
332e9569 720 drRegion = kFALSE;
721 amRegion = kFALSE;
722 cIdCurrent = gMC->CurrentVolName();
e6674585 723 if (cIdSensDr == cIdCurrent[1]) {
332e9569 724 drRegion = kTRUE;
725 }
e6674585 726 if (cIdSensAm == cIdCurrent[1]) {
332e9569 727 amRegion = kTRUE;
728 }
729 if (drRegion || amRegion) {
fe4da5cc 730
5c7f4665 731 // The hit coordinates and charge
732 gMC->TrackPosition(pos);
733 hits[0] = pos[0];
734 hits[1] = pos[1];
735 hits[2] = pos[2];
5c7f4665 736
2c8bf4aa 737 // The sector number (0 - 17), according to standard coordinate system
738 cIdPath = gGeoManager->GetPath();
739 cIdSector[0] = cIdPath[21];
740 cIdSector[1] = cIdPath[22];
741 sec = atoi(cIdSector);
82bbf98a 742
332e9569 743 // The plane and chamber number
744 cIdChamber[0] = cIdCurrent[2];
745 cIdChamber[1] = cIdCurrent[3];
e644678a 746 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 747 cha = ((Int_t) idChamber / kNplan);
332e9569 748 pla = ((Int_t) idChamber % kNplan);
82bbf98a 749
ce0d6231 750 // The detector number
751 det = fGeometry->GetDetector(pla,cha,sec);
5c7f4665 752
ce0d6231 753 // Special hits only in the drift region
754 if ((drRegion) &&
755 (gMC->IsTrackEntering())) {
5c7f4665 756
ce0d6231 757 // Create a track reference at the entrance of each
758 // chamber that contains the momentum components of the particle
759 gMC->TrackMomentum(mom);
760 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
793ff80c 761
ce0d6231 762 // Create the hits from TR photons if electron/positron is
763 // entering the drift volume
764 if ((fTR) &&
765 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
766 CreateTRhit(det);
767 }
f73816f5 768
ce0d6231 769 }
770 else if ((amRegion) &&
771 (gMC->IsTrackExiting())) {
f73816f5 772
ce0d6231 773 // Create a track reference at the exit of each
774 // chamber that contains the momentum components of the particle
775 gMC->TrackMomentum(mom);
776 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
f73816f5 777
ce0d6231 778 }
779
780 // Calculate the energy of the delta-electrons
781 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
782 eDelta = TMath::Max(eDelta,0.0);
783
784 // Generate the electron cluster size
785 if (eDelta > 0.0) {
786
787 qTot = ((Int_t) (eDelta / kWion) + 1);
f73816f5 788
030b4415 789 // Create a new dEdx hit
332e9569 790 if (drRegion) {
a328fff9 791 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 792 ,det
793 ,hits
794 ,qTot
25ca55ce 795 ,gMC->TrackTime()*1.0e06
030b4415 796 ,kTRUE);
797 }
5c7f4665 798 else {
a328fff9 799 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 800 ,det
801 ,hits
802 ,qTot
25ca55ce 803 ,gMC->TrackTime()*1.0e06
030b4415 804 ,kFALSE);
805 }
f73816f5 806
ce0d6231 807 }
808
809 // Calculate the maximum step size for the next tracking step
810 // Produce only one hit if Ekin is below cutoff
811 aMass = gMC->TrackMass();
812 if ((gMC->Etot() - aMass) > kEkinMinStep) {
813
814 // The energy loss according to Bethe Bloch
815 iPdg = TMath::Abs(gMC->TrackPid());
816 if ((iPdg != kPdgElectron) ||
817 ((iPdg == kPdgElectron) &&
818 (pTot < kPTotMaxEl))) {
819 gMC->TrackMomentum(mom);
820 pTot = mom.Rho();
821 betaGamma = pTot / aMass;
822 pp = kPrim * BetheBloch(betaGamma);
823 // Take charge > 1 into account
824 charge = gMC->TrackCharge();
825 if (TMath::Abs(charge) > 1) {
826 pp = pp * charge*charge;
f73816f5 827 }
ce0d6231 828 }
829 else {
830 // Electrons above 20 Mev/c are at the plateau
831 pp = kPrim * kPlateau;
832 }
f73816f5 833
ce0d6231 834 if (pp > 0.0) {
835 do {
836 gMC->GetRandom()->RndmArray(1,random);
030b4415 837 }
ce0d6231 838 while ((random[0] == 1.0) ||
839 (random[0] == 0.0));
840 stepSize = - TMath::Log(random[0]) / pp;
841 gMC->SetMaxStep(stepSize);
842 }
030b4415 843
5c7f4665 844 }
030b4415 845
d3f347ff 846 }
030b4415 847
5c7f4665 848 }
030b4415 849
5c7f4665 850}
851
852//_____________________________________________________________________________
a328fff9 853void AliTRDv1::StepManagerFixedStep()
854{
855 //
856 // Slow simulator. Every charged track produces electron cluster as hits
857 // along its path across the drift volume. The step size is fixed in
858 // this version of the step manager.
859 //
860
ce0d6231 861 // PDG code electron
862 const Int_t kPdgElectron = 11;
863
a328fff9 864 Int_t pla = 0;
865 Int_t cha = 0;
866 Int_t sec = 0;
867 Int_t det = 0;
868 Int_t qTot;
869
870 Float_t hits[3];
871 Double_t eDep;
872
873 Bool_t drRegion = kFALSE;
874 Bool_t amRegion = kFALSE;
875
2c8bf4aa 876 TString cIdPath;
877 Char_t cIdSector[3];
878 cIdSector[2] = 0;
879
a328fff9 880 TString cIdCurrent;
881 TString cIdSensDr = "J";
882 TString cIdSensAm = "K";
883 Char_t cIdChamber[3];
2c8bf4aa 884 cIdChamber[2] = 0;
a328fff9 885
030b4415 886 TLorentzVector pos;
887 TLorentzVector mom;
a328fff9 888
889 const Int_t kNplan = AliTRDgeometry::Nplan();
890 const Int_t kNcham = AliTRDgeometry::Ncham();
891 const Int_t kNdetsec = kNplan * kNcham;
892
030b4415 893 const Double_t kBig = 1.0e+12;
a328fff9 894
bc327ce2 895 const Float_t kWion = 23.53; // Ionization energy
a328fff9 896 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
897
898 // Set the maximum step size to a very large number for all
899 // neutral particles and those outside the driftvolume
900 gMC->SetMaxStep(kBig);
901
902 // If not charged track or already stopped or disappeared, just return.
903 if ((!gMC->TrackCharge()) ||
ce0d6231 904 gMC->IsTrackDisappeared()) {
905 return;
906 }
a328fff9 907
908 // Inside a sensitive volume?
909 cIdCurrent = gMC->CurrentVolName();
910
ce0d6231 911 if (cIdSensDr == cIdCurrent[1]) {
912 drRegion = kTRUE;
913 }
914 if (cIdSensAm == cIdCurrent[1]) {
915 amRegion = kTRUE;
916 }
a328fff9 917
030b4415 918 if ((!drRegion) &&
919 (!amRegion)) {
920 return;
921 }
a328fff9 922
923 // The hit coordinates and charge
924 gMC->TrackPosition(pos);
925 hits[0] = pos[0];
926 hits[1] = pos[1];
927 hits[2] = pos[2];
928
2c8bf4aa 929 // The sector number (0 - 17), according to standard coordinate system
930 cIdPath = gGeoManager->GetPath();
931 cIdSector[0] = cIdPath[21];
932 cIdSector[1] = cIdPath[22];
933 sec = atoi(cIdSector);
a328fff9 934
935 // The plane and chamber number
030b4415 936 cIdChamber[0] = cIdCurrent[2];
937 cIdChamber[1] = cIdCurrent[3];
a328fff9 938 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
8a497c18 939 cha = ((Int_t) idChamber / kNplan);
a328fff9 940 pla = ((Int_t) idChamber % kNplan);
e0d47c25 941
030b4415 942 // The detector number
943 det = fGeometry->GetDetector(pla,cha,sec);
944
25ca55ce 945 // 0: InFlight 1:Entering 2:Exiting
030b4415 946 Int_t trkStat = 0;
a328fff9 947
948 // Special hits only in the drift region
ce0d6231 949 if ((drRegion) &&
950 (gMC->IsTrackEntering())) {
a328fff9 951
ce0d6231 952 // Create a track reference at the entrance of each
953 // chamber that contains the momentum components of the particle
954 gMC->TrackMomentum(mom);
955 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
956 trkStat = 1;
a328fff9 957
ce0d6231 958 // Create the hits from TR photons if electron/positron is
959 // entering the drift volume
960 if ((fTR) &&
961 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
030b4415 962 CreateTRhit(det);
963 }
a328fff9 964
965 }
ce0d6231 966 else if ((amRegion) &&
967 (gMC->IsTrackExiting())) {
968
969 // Create a track reference at the exit of each
970 // chamber that contains the momentum components of the particle
971 gMC->TrackMomentum(mom);
972 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
973 trkStat = 2;
974
975 }
a328fff9 976
977 // Calculate the charge according to GEANT Edep
978 // Create a new dEdx hit
979 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
980 qTot = (Int_t) (eDep / kWion);
ce0d6231 981 if ((qTot) ||
982 (trkStat)) {
983 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
984 ,det
985 ,hits
986 ,qTot
25ca55ce 987 ,gMC->TrackTime()*1.0e06
ce0d6231 988 ,drRegion);
989 }
a328fff9 990
991 // Set Maximum Step Size
992 // Produce only one hit if Ekin is below cutoff
030b4415 993 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
994 return;
995 }
a328fff9 996 gMC->SetMaxStep(fStepSize);
997
998}
999
1000//_____________________________________________________________________________
5c7f4665 1001Double_t AliTRDv1::BetheBloch(Double_t bg)
1002{
1003 //
1004 // Parametrization of the Bethe-Bloch-curve
1005 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1006 //
1007
1008 // This parameters have been adjusted to averaged values from GEANT
f57bb418 1009 const Double_t kP1 = 7.17960e-02;
1010 const Double_t kP2 = 8.54196;
1011 const Double_t kP3 = 1.38065e-06;
1012 const Double_t kP4 = 5.30972;
1013 const Double_t kP5 = 2.83798;
5c7f4665 1014
f73816f5 1015 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1016 const Double_t kBgMin = 0.8;
1017 const Double_t kBBMax = 6.83298;
f73816f5 1018
1019 if (bg > kBgMin) {
030b4415 1020 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
5c7f4665 1021 Double_t aa = TMath::Power(yy,kP4);
030b4415 1022 Double_t bb = TMath::Power((1.0/bg),kP5);
5c7f4665 1023 bb = TMath::Log(kP3 + bb);
030b4415 1024 return ((kP2 - aa - bb) * kP1 / aa);
5c7f4665 1025 }
f73816f5 1026 else {
1027 return kBBMax;
1028 }
d3f347ff 1029
fe4da5cc 1030}
5c7f4665 1031
1032//_____________________________________________________________________________
c4214bc0 1033Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
a328fff9 1034{
1035 //
1036 // Return dN/dx (number of primary collisions per centimeter)
1037 // for given beta*gamma factor.
1038 //
1039 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1040 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1041 // This must be used as a set with IntSpecGeant.
1042 //
1043
030b4415 1044 Int_t i = 0;
a328fff9 1045
030b4415 1046 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1047 , 1.800000, 2.000000, 2.500000, 3.000000
1048 , 4.000000, 7.000000, 10.000000, 20.000000
1049 , 40.000000, 70.000000, 100.000000, 300.000000
1050 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
a328fff9 1051
030b4415 1052 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1053 , 22.734999, 21.411915, 19.934095, 19.449375
1054 , 19.344431, 20.185553, 21.027925, 22.912676
1055 , 24.933352, 26.504053, 27.387468, 29.566597
1056 , 30.353779, 30.787134, 31.129285, 31.157350 };
1057
1058 // Betagamma to gamma
1059 Double_t g = TMath::Sqrt(1.0 + bg*bg);
a328fff9 1060
1061 // Find the index just before the point we need.
030b4415 1062 for (i = 0; i < 18; i++) {
1063 if ((arrG[i] < g) &&
1064 (arrG[i+1] > g)) {
a328fff9 1065 break;
030b4415 1066 }
1067 }
a328fff9 1068
1069 // Simple interpolation.
030b4415 1070 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1071 * (g - arrG[i]) + arrNC[i];
a328fff9 1072
030b4415 1073 return pp;
a328fff9 1074
1075}
1076
1077//_____________________________________________________________________________
5c7f4665 1078Double_t Ermilova(Double_t *x, Double_t *)
1079{
1080 //
1081 // Calculates the delta-ray energy distribution according to Ermilova.
1082 // Logarithmic scale !
1083 //
1084
1085 Double_t energy;
1086 Double_t dpos;
1087 Double_t dnde;
1088
030b4415 1089 Int_t pos1;
1090 Int_t pos2;
5c7f4665 1091
8230f242 1092 const Int_t kNv = 31;
5c7f4665 1093
030b4415 1094 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1095 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1096 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1097 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1098 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1099 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1100 , 11.5129 };
1101
1102 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1103 , 20.9, 20.8, 20.0, 16.0, 11.0
1104 , 8.0, 6.0, 5.2, 4.6, 4.0
1105 , 3.5, 3.0, 1.4, 0.67, 0.44
1106 , 0.3, 0.18, 0.12, 0.08, 0.056
1107 , 0.04, 0.023, 0.015, 0.011, 0.01
1108 , 0.004 };
5c7f4665 1109
1110 energy = x[0];
1111
1112 // Find the position
030b4415 1113 pos1 = 0;
1114 pos2 = 0;
5c7f4665 1115 dpos = 0;
1116 do {
1117 dpos = energy - vxe[pos2++];
1118 }
1119 while (dpos > 0);
1120 pos2--;
030b4415 1121 if (pos2 > kNv) {
1122 pos2 = kNv - 1;
1123 }
5c7f4665 1124 pos1 = pos2 - 1;
1125
1126 // Differentiate between the sampling points
1127 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1128
1129 return dnde;
1130
1131}
a328fff9 1132
1133//_____________________________________________________________________________
1134Double_t IntSpecGeant(Double_t *x, Double_t *)
1135{
1136 //
1137 // Integrated spectrum from Geant3
1138 //
1139
96efaf83 1140 const Int_t npts = 83;
030b4415 1141 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1142 , 2.672067, 2.813299, 3.015059, 3.216819
1143 , 3.418579, 3.620338, 3.868209, 3.920198
1144 , 3.978284, 4.063923, 4.186264, 4.308605
1145 , 4.430946, 4.553288, 4.724261, 4.837736
1146 , 4.999842, 5.161949, 5.324056, 5.486163
1147 , 5.679688, 5.752998, 5.857728, 5.962457
1148 , 6.067185, 6.171914, 6.315653, 6.393674
1149 , 6.471694, 6.539689, 6.597658, 6.655627
1150 , 6.710957, 6.763648, 6.816338, 6.876198
1151 , 6.943227, 7.010257, 7.106285, 7.252151
1152 , 7.460531, 7.668911, 7.877290, 8.085670
1153 , 8.302979, 8.353585, 8.413120, 8.483500
1154 , 8.541030, 8.592857, 8.668865, 8.820485
1155 , 9.037086, 9.253686, 9.470286, 9.686887
1156 , 9.930838, 9.994655, 10.085822, 10.176990
1157 , 10.268158, 10.359325, 10.503614, 10.627565
1158 , 10.804637, 10.981709, 11.158781, 11.335854
1159 , 11.593397, 11.781165, 12.049404, 12.317644
1160 , 12.585884, 12.854123, 14.278421, 16.975889
1161 , 20.829416, 24.682943, 28.536469 };
1162
1163 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1164 , 9.1601500, 8.206670, 6.919630, 5.655430
1165 , 4.6221300, 3.777610, 3.019560, 2.591950
1166 , 2.5414600, 2.712920, 3.327460, 4.928240
1167 , 7.6185300, 10.966700, 12.225800, 8.094750
1168 , 3.3586900, 1.553650, 1.209600, 1.263840
1169 , 1.3241100, 1.312140, 1.255130, 1.165770
1170 , 1.0594500, 0.945450, 0.813231, 0.699837
1171 , 0.6235580, 2.260990, 2.968350, 2.240320
1172 , 1.7988300, 1.553300, 1.432070, 1.535520
1173 , 1.4429900, 1.247990, 1.050750, 0.829549
1174 , 0.5900280, 0.395897, 0.268741, 0.185320
1175 , 0.1292120, 0.103545, 0.0949525, 0.101535
1176 , 0.1276380, 0.134216, 0.123816, 0.104557
1177 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1178 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1179 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1180 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1181 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1182 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1183 , 3.63304e-06, 0.0000000, 0.0000000 };
1184
1185 Int_t i;
a328fff9 1186 Double_t energy = x[0];
a328fff9 1187
030b4415 1188 for (i = 0; i < npts; i++) {
1189 if (energy < arre[i]) {
1190 break;
1191 }
1192 }
a328fff9 1193
030b4415 1194 if (i == 0) {
1195 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");
1196 }
a328fff9 1197
f57bb418 1198 return arrdnde[i];
a328fff9 1199
1200}