Modify services of top most layer (inside TOF acceptance)
[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
8230f242 84//_____________________________________________________________________________
030b4415 85AliTRDv1::AliTRDv1(const AliTRDv1 &trd)
86 :AliTRD(trd)
87 ,fTRon(trd.fTRon)
88 ,fTR(NULL)
89 ,fTypeOfStepManager(trd.fTypeOfStepManager)
90 ,fStepSize(trd.fStepSize)
91 ,fDeltaE(NULL)
92 ,fDeltaG(NULL)
93 ,fTrackLength0(trd.fTrackLength0)
94 ,fPrimaryTrackPid(trd.fPrimaryTrackPid)
8230f242 95{
96 //
97 // Copy constructor
98 //
99
030b4415 100 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
101 fDeltaG->Copy(*((AliTRDv1 &) trd).fDeltaG);
102 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 103
104}
105
5c7f4665 106//_____________________________________________________________________________
107AliTRDv1::~AliTRDv1()
108{
dd9a6ee3 109 //
110 // AliTRDv1 destructor
111 //
82bbf98a 112
030b4415 113 if (fDeltaE) {
114 delete fDeltaE;
115 fDeltaE = 0;
116 }
117
118 if (fDeltaG) {
119 delete fDeltaG;
120 fDeltaG = 0;
121 }
122
123 if (fTR) {
124 delete fTR;
125 fTR = 0;
126 }
82bbf98a 127
fe4da5cc 128}
129
dd9a6ee3 130//_____________________________________________________________________________
131AliTRDv1 &AliTRDv1::operator=(const AliTRDv1 &trd)
132{
133 //
134 // Assignment operator
135 //
136
137 if (this != &trd) ((AliTRDv1 &) trd).Copy(*this);
030b4415 138
dd9a6ee3 139 return *this;
140
141}
8230f242 142
143//_____________________________________________________________________________
e0d47c25 144void AliTRDv1::Copy(TObject &trd) const
8230f242 145{
146 //
147 // Copy function
148 //
149
a328fff9 150 ((AliTRDv1 &) trd).fTypeOfStepManager = fTypeOfStepManager;
151 ((AliTRDv1 &) trd).fStepSize = fStepSize;
bd0f8685 152 ((AliTRDv1 &) trd).fTRon = fTRon;
030b4415 153 ((AliTRDv1 &) trd).fTrackLength0 = fTrackLength0;
154 ((AliTRDv1 &) trd).fPrimaryTrackPid = fPrimaryTrackPid;
bd0f8685 155
793ff80c 156 fDeltaE->Copy(*((AliTRDv1 &) trd).fDeltaE);
a328fff9 157 fDeltaG->Copy(*((AliTRDv1 &) trd).fDeltaG);
793ff80c 158 fTR->Copy(*((AliTRDv1 &) trd).fTR);
8230f242 159
160}
161
f57bb418 162//_____________________________________________________________________________
163void AliTRDv1::AddAlignableVolumes() const
164{
165 //
166 // Create entries for alignable volumes associating the symbolic volume
167 // name with the corresponding volume path. Needs to be syncronized with
168 // eventual changes in the geometry.
169 //
170
171 TString volPath;
172 TString symName;
173
174 TString vpStr = "ALIC_1/B077_1/BSEGMO";
175 TString vpApp1 = "_1/BTRD";
176 TString vpApp2 = "_1";
177 TString vpApp3 = "/UTR1_1/UTS1_1/UTI1_1/UT";
178
179 TString snStr = "TRD/sm";
180 TString snApp1 = "/st";
181 TString snApp2 = "/pl";
182
183 //
184 // The super modules
185 // The symbolic names are: TRD/sm00
186 // ...
187 // TRD/sm17
188 //
189 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
190
191 volPath = vpStr;
192 volPath += isect;
193 volPath += vpApp1;
194 volPath += isect;
195 volPath += vpApp2;
196
197 symName = snStr;
198 symName += Form("%02d",isect);
199
200 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
201
202 }
203
204 //
205 // The readout chambers
206 // The symbolic names are: TRD/sm00/st0/pl0
207 // ...
208 // TRD/sm17/st4/pl5
209 //
210 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
211 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
212 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
213
214 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
215
216 volPath = vpStr;
217 volPath += isect;
218 volPath += vpApp1;
219 volPath += isect;
220 volPath += vpApp2;
221 volPath += vpApp3;
222 volPath += Form("%02d",idet);
223 volPath += vpApp2;
224
225 symName = snStr;
226 symName += Form("%02d",isect);
227 symName += snApp1;
228 symName += icham;
229 symName += snApp2;
230 symName += iplan;
231
f57bb418 232 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
233
234 }
235 }
236 }
237
238}
239
fe4da5cc 240//_____________________________________________________________________________
241void AliTRDv1::CreateGeometry()
242{
243 //
851d3db9 244 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
5c7f4665 245 // This version covers the full azimuth.
d3f347ff 246 //
247
82bbf98a 248 // Check that FRAME is there otherwise we have no place where to put the TRD
8230f242 249 AliModule* frame = gAlice->GetModule("FRAME");
030b4415 250 if (!frame) {
251 AliError("TRD needs FRAME to be present\n");
252 return;
253 }
d3f347ff 254
82bbf98a 255 // Define the chambers
256 AliTRD::CreateGeometry();
d3f347ff 257
fe4da5cc 258}
259
260//_____________________________________________________________________________
261void AliTRDv1::CreateMaterials()
262{
263 //
851d3db9 264 // Create materials for the Transition Radiation Detector version 1
fe4da5cc 265 //
82bbf98a 266
d3f347ff 267 AliTRD::CreateMaterials();
82bbf98a 268
fe4da5cc 269}
270
793ff80c 271//_____________________________________________________________________________
272void AliTRDv1::CreateTRhit(Int_t det)
273{
274 //
275 // Creates an electron cluster from a TR photon.
276 // The photon is assumed to be created a the end of the radiator. The
277 // distance after which it deposits its energy takes into account the
278 // absorbtion of the entrance window and of the gas mixture in drift
279 // volume.
280 //
281
282 // PDG code electron
283 const Int_t kPdgElectron = 11;
284
285 // Ionization energy
bc327ce2 286 const Float_t kWion = 23.53;
793ff80c 287
288 // Maximum number of TR photons per track
289 const Int_t kNTR = 50;
290
030b4415 291 TLorentzVector mom;
292 TLorentzVector pos;
793ff80c 293
793ff80c 294 // Create TR at the entrance of the chamber
295 if (gMC->IsTrackEntering()) {
296
f73816f5 297 // Create TR only for electrons
298 Int_t iPdg = gMC->TrackPid();
030b4415 299 if (TMath::Abs(iPdg) != kPdgElectron) {
300 return;
301 }
f73816f5 302
793ff80c 303 Float_t eTR[kNTR];
304 Int_t nTR;
305
306 // Create TR photons
307 gMC->TrackMomentum(mom);
308 Float_t pTot = mom.Rho();
309 fTR->CreatePhotons(iPdg,pTot,nTR,eTR);
310 if (nTR > kNTR) {
45160b1f 311 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
793ff80c 312 }
313
314 // Loop through the TR photons
315 for (Int_t iTR = 0; iTR < nTR; iTR++) {
316
317 Float_t energyMeV = eTR[iTR] * 0.001;
318 Float_t energyeV = eTR[iTR] * 1000.0;
030b4415 319 Float_t absLength = 0.0;
320 Float_t sigma = 0.0;
793ff80c 321
322 // Take the absorbtion in the entrance window into account
323 Double_t muMy = fTR->GetMuMy(energyMeV);
030b4415 324 sigma = muMy * fFoilDensity;
842287f2 325 if (sigma > 0.0) {
326 absLength = gRandom->Exp(1.0/sigma);
030b4415 327 if (absLength < AliTRDgeometry::MyThick()) {
328 continue;
329 }
842287f2 330 }
331 else {
332 continue;
333 }
793ff80c 334
335 // The absorbtion cross sections in the drift gas
3dac2b2d 336 // Gas-mixture (Xe/CO2)
337 Double_t muXe = fTR->GetMuXe(energyMeV);
338 Double_t muCO = fTR->GetMuCO(energyMeV);
339 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
793ff80c 340
341 // The distance after which the energy of the TR photon
342 // is deposited.
842287f2 343 if (sigma > 0.0) {
344 absLength = gRandom->Exp(1.0/sigma);
a328fff9 345 if (absLength > (AliTRDgeometry::DrThick()
346 + AliTRDgeometry::AmThick())) {
347 continue;
348 }
842287f2 349 }
350 else {
351 continue;
352 }
793ff80c 353
354 // The position of the absorbtion
355 Float_t posHit[3];
356 gMC->TrackPosition(pos);
357 posHit[0] = pos[0] + mom[0] / pTot * absLength;
358 posHit[1] = pos[1] + mom[1] / pTot * absLength;
c4214bc0 359 posHit[2] = pos[2] + mom[2] / pTot * absLength;
793ff80c 360
361 // Create the charge
362 Int_t q = ((Int_t) (energyeV / kWion));
363
364 // Add the hit to the array. TR photon hits are marked
365 // by negative charge
030b4415 366 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
367 ,det
368 ,posHit
369 ,-q
370 ,kTRUE);
793ff80c 371
372 }
373
374 }
375
376}
377
5c7f4665 378//_____________________________________________________________________________
379void AliTRDv1::Init()
380{
381 //
382 // Initialise Transition Radiation Detector after geometry has been built.
5c7f4665 383 //
384
385 AliTRD::Init();
386
45160b1f 387 AliDebug(1,"Slow simulator\n");
bd0f8685 388
389 // Switch on TR simulation as default
390 if (!fTRon) {
45160b1f 391 AliInfo("TR simulation off");
bd0f8685 392 }
393 else {
394 fTR = new AliTRDsim();
395 }
5c7f4665 396
397 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
398 const Float_t kPoti = 12.1;
399 // Maximum energy (50 keV);
400 const Float_t kEend = 50000.0;
401 // Ermilova distribution for the delta-ray spectrum
030b4415 402 Float_t poti = TMath::Log(kPoti);
403 Float_t eEnd = TMath::Log(kEend);
a328fff9 404
405 // Ermilova distribution for the delta-ray spectrum
c4214bc0 406 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
a328fff9 407
408 // Geant3 distribution for the delta-ray spectrum
c4214bc0 409 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
5c7f4665 410
45160b1f 411 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
5c7f4665 412
fe4da5cc 413}
414
5c7f4665 415//_____________________________________________________________________________
416void AliTRDv1::StepManager()
a328fff9 417{
418 //
c4214bc0 419 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 420 // along its path across the drift volume.
421 //
422
423 switch (fTypeOfStepManager) {
a6dd11e9 424 case 0:
425 StepManagerErmilova();
426 break;
427 case 1:
428 StepManagerGeant();
429 break;
430 case 2:
431 StepManagerFixedStep();
432 break;
433 default:
434 AliWarning("Not a valid Step Manager.");
a328fff9 435 }
436
437}
438
439//_____________________________________________________________________________
440void AliTRDv1::SelectStepManager(Int_t t)
441{
442 //
443 // Selects a step manager type:
444 // 0 - Ermilova
445 // 1 - Geant3
446 // 2 - Fixed step size
447 //
448
a328fff9 449 fTypeOfStepManager = t;
45160b1f 450 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
a328fff9 451
452}
453
454//_____________________________________________________________________________
455void AliTRDv1::StepManagerGeant()
456{
457 //
c4214bc0 458 // Slow simulator. Every charged track produces electron cluster as hits
a328fff9 459 // along its path across the drift volume. The step size is set acording
460 // to Bethe-Bloch. The energy distribution of the delta electrons follows
461 // a spectrum taken from Geant3.
462 //
f2e3a0b5 463 // Version by A. Bercuci
464 //
465
c4214bc0 466 Int_t pla = 0;
467 Int_t cha = 0;
468 Int_t sec = 0;
469 Int_t det = 0;
470 Int_t iPdg;
471 Int_t qTot;
472
473 Float_t hits[3];
474 Float_t charge;
475 Float_t aMass;
476
030b4415 477 Double_t pTot = 0;
c4214bc0 478 Double_t eDelta;
030b4415 479 Double_t betaGamma;
480 Double_t pp;
f2e3a0b5 481 Double_t stepSize = 0;
c4214bc0 482
483 Bool_t drRegion = kFALSE;
484 Bool_t amRegion = kFALSE;
485
486 TString cIdCurrent;
487 TString cIdSensDr = "J";
488 TString cIdSensAm = "K";
489 Char_t cIdChamber[3];
490 cIdChamber[2] = 0;
491
030b4415 492 TLorentzVector pos;
493 TLorentzVector mom;
c4214bc0 494
030b4415 495 TArrayI processes;
f2e3a0b5 496
c4214bc0 497 const Int_t kNplan = AliTRDgeometry::Nplan();
498 const Int_t kNcham = AliTRDgeometry::Ncham();
499 const Int_t kNdetsec = kNplan * kNcham;
500
030b4415 501 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 502 const Float_t kWion = 23.53; // Ionization energy
c4214bc0 503 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
504
505 // Minimum energy for the step size adjustment
506 const Float_t kEkinMinStep = 1.0e-5;
507 // energy threshold for production of delta electrons
f2e3a0b5 508 const Float_t kECut = 1.0e4;
509 // Parameters entering the parametrized range for delta electrons
030b4415 510 const Float_t kRa = 5.37e-4;
f2e3a0b5 511 const Float_t kRb = 0.9815;
030b4415 512 const Float_t kRc = 3.123e-3;
f2e3a0b5 513 // Gas density -> To be made user adjustable !
030b4415 514 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
515 const Float_t kRho = 0.004945 ;
a328fff9 516
c4214bc0 517 // Plateau value of the energy-loss for electron in xenon
030b4415 518 // The averaged value (26/3/99)
c4214bc0 519 const Float_t kPlateau = 1.55;
030b4415 520 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
521 const Float_t kPrim = 19.34;
c4214bc0 522 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
523 const Float_t kPoti = 12.1;
030b4415 524 // PDG code electron
525 const Int_t kPdgElectron = 11;
c4214bc0 526
527 // Set the maximum step size to a very large number for all
528 // neutral particles and those outside the driftvolume
529 gMC->SetMaxStep(kBig);
530
531 // Use only charged tracks
532 if (( gMC->TrackCharge() ) &&
c4214bc0 533 (!gMC->IsTrackDisappeared())) {
534
535 // Inside a sensitive volume?
536 drRegion = kFALSE;
537 amRegion = kFALSE;
538 cIdCurrent = gMC->CurrentVolName();
539 if (cIdSensDr == cIdCurrent[1]) {
540 drRegion = kTRUE;
541 }
542 if (cIdSensAm == cIdCurrent[1]) {
543 amRegion = kTRUE;
544 }
545 if (drRegion || amRegion) {
a328fff9 546
c4214bc0 547 // The hit coordinates and charge
548 gMC->TrackPosition(pos);
549 hits[0] = pos[0];
550 hits[1] = pos[1];
551 hits[2] = pos[2];
552
553 // The sector number (0 - 17)
554 // The numbering goes clockwise and starts at y = 0
555 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
030b4415 556 if (phi < 90.0) {
557 phi = phi + 270.0;
558 }
559 else {
560 phi = phi - 90.0;
561 }
562 sec = ((Int_t) (phi / 20.0));
c4214bc0 563
564 // The plane and chamber number
030b4415 565 cIdChamber[0] = cIdCurrent[2];
566 cIdChamber[1] = cIdCurrent[3];
c4214bc0 567 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
568 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
569 pla = ((Int_t) idChamber % kNplan);
570
571 // Check on selected volumes
572 Int_t addthishit = 1;
c4214bc0 573
574 // Add this hit
575 if (addthishit) {
576
577 // The detector number
578 det = fGeometry->GetDetector(pla,cha,sec);
579
580 // Special hits only in the drift region
581 if (drRegion) {
f2e3a0b5 582
c4214bc0 583 // Create a track reference at the entrance and
584 // exit of each chamber that contain the
f2e3a0b5 585 // momentum components of the particle
030b4415 586 if (gMC->IsTrackEntering() ||
587 gMC->IsTrackExiting()) {
c4214bc0 588 gMC->TrackMomentum(mom);
589 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
590 }
f2e3a0b5 591
030b4415 592 if (gMC->IsTrackEntering() &&
593 !gMC->IsNewTrack()) {
f2e3a0b5 594 // determine if hit belong to primary track
595 fPrimaryTrackPid = gAlice->GetMCApp()->GetCurrentTrackNumber();
596 // determine track length when entering the detector
597 fTrackLength0 = gMC->TrackLength();
598 }
c4214bc0 599
f2e3a0b5 600 // Create the hits from TR photons
c4214bc0 601 if (fTR) CreateTRhit(det);
c4214bc0 602
f2e3a0b5 603 }
c4214bc0 604
f2e3a0b5 605 // Calculate the energy of the delta-electrons
606 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
607 // take into account correlation with the underlying GEANT tracking
608 // mechanism. see
609 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
610 //
611 // determine the most significant process (last on the processes list)
612 // which caused this hit
c4214bc0 613 gMC->StepProcesses(processes);
f2e3a0b5 614 Int_t nofprocesses = processes.GetSize();
615 Int_t pid;
616 if (!nofprocesses) {
617 pid = 0;
618 }
619 else {
620 pid = processes[nofprocesses-1];
621 }
622
623 // generate Edep according to GEANT parametrisation
624 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
625 eDelta = TMath::Max(eDelta,0.0);
030b4415 626 Float_t prRange = 0.0;
627 Float_t range = gMC->TrackLength() - fTrackLength0;
f2e3a0b5 628 // merge GEANT tracker information with locally cooked one
629 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
f2e3a0b5 630 if (pid == 27) {
631 if (eDelta >= kECut) {
030b4415 632 prRange = kRa * eDelta * 0.001
633 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
634 if (prRange >= (3.7 - range)) {
635 eDelta *= 0.1;
636 }
f2e3a0b5 637 }
638 }
639 else if (pid == 1) {
640 if (eDelta < kECut) {
641 eDelta *= 0.5;
642 }
643 else {
030b4415 644 prRange = kRa * eDelta * 0.001
645 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
646 if (prRange >= ((AliTRDgeometry::DrThick()
647 + AliTRDgeometry::AmThick()) - range)) {
f2e3a0b5 648 eDelta *= 0.05;
649 }
650 else {
651 eDelta *= 0.5;
652 }
653 }
654 }
655 else {
656 eDelta = 0.0;
657 }
658 }
659 else {
660 eDelta = 0.0;
661 }
c4214bc0 662
663 // Generate the electron cluster size
f2e3a0b5 664 if (eDelta == 0.0) {
665 qTot = 0;
666 }
667 else {
668 qTot = ((Int_t) (eDelta / kWion) + 1);
669 }
670
671 // Create a new dEdx hit
030b4415 672 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
673 ,det
674 ,hits
675 ,qTot
676 ,drRegion);
c4214bc0 677
678 // Calculate the maximum step size for the next tracking step
679 // Produce only one hit if Ekin is below cutoff
680 aMass = gMC->TrackMass();
681 if ((gMC->Etot() - aMass) > kEkinMinStep) {
682
683 // The energy loss according to Bethe Bloch
f2e3a0b5 684 iPdg = TMath::Abs(gMC->TrackPid());
685 if ((iPdg != kPdgElectron) ||
030b4415 686 ((iPdg == kPdgElectron) &&
687 (pTot < kPTotMaxEl))) {
c4214bc0 688 gMC->TrackMomentum(mom);
689 pTot = mom.Rho();
690 betaGamma = pTot / aMass;
691 pp = BetheBlochGeant(betaGamma);
f2e3a0b5 692 // Take charge > 1 into account
030b4415 693 charge = gMC->TrackCharge();
f2e3a0b5 694 if (TMath::Abs(charge) > 1) {
695 pp = pp * charge*charge;
696 }
697 }
698 else {
699 // Electrons above 20 Mev/c are at the plateau
700 pp = kPrim * kPlateau;
c4214bc0 701 }
702
1b775a44 703 Int_t nsteps = 0;
030b4415 704 do {
705 nsteps = gRandom->Poisson(pp);
706 } while(!nsteps);
707 stepSize = 1.0 / nsteps;
1b775a44 708 gMC->SetMaxStep(stepSize);
f2e3a0b5 709
1b775a44 710 }
f2e3a0b5 711
c4214bc0 712 }
f2e3a0b5 713
c4214bc0 714 }
f2e3a0b5 715
c4214bc0 716 }
f2e3a0b5 717
a328fff9 718}
719
720//_____________________________________________________________________________
721void AliTRDv1::StepManagerErmilova()
5c7f4665 722{
723 //
5c7f4665 724 // Slow simulator. Every charged track produces electron cluster as hits
725 // along its path across the drift volume. The step size is set acording
726 // to Bethe-Bloch. The energy distribution of the delta electrons follows
727 // a spectrum taken from Ermilova et al.
728 //
729
851d3db9 730 Int_t pla = 0;
731 Int_t cha = 0;
732 Int_t sec = 0;
793ff80c 733 Int_t det = 0;
851d3db9 734 Int_t iPdg;
793ff80c 735 Int_t qTot;
5c7f4665 736
793ff80c 737 Float_t hits[3];
a5cadd36 738 Double_t random[1];
5c7f4665 739 Float_t charge;
740 Float_t aMass;
741
030b4415 742 Double_t pTot = 0.0;
5c7f4665 743 Double_t eDelta;
030b4415 744 Double_t betaGamma;
745 Double_t pp;
f73816f5 746 Double_t stepSize;
5c7f4665 747
332e9569 748 Bool_t drRegion = kFALSE;
749 Bool_t amRegion = kFALSE;
750
751 TString cIdCurrent;
752 TString cIdSensDr = "J";
753 TString cIdSensAm = "K";
593a9fc3 754 Char_t cIdChamber[3];
755 cIdChamber[2] = 0;
332e9569 756
030b4415 757 TLorentzVector pos;
758 TLorentzVector mom;
82bbf98a 759
332e9569 760 const Int_t kNplan = AliTRDgeometry::Nplan();
e644678a 761 const Int_t kNcham = AliTRDgeometry::Ncham();
762 const Int_t kNdetsec = kNplan * kNcham;
763
030b4415 764 const Double_t kBig = 1.0e+12; // Infinitely big
bc327ce2 765 const Float_t kWion = 23.53; // Ionization energy
a328fff9 766 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
5c7f4665 767
f73816f5 768 // Minimum energy for the step size adjustment
769 const Float_t kEkinMinStep = 1.0e-5;
a328fff9 770
5c7f4665 771 // Plateau value of the energy-loss for electron in xenon
030b4415 772 // The averaged value (26/3/99)
a3c76cdc 773 const Float_t kPlateau = 1.55;
030b4415 774 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
775 const Float_t kPrim = 48.0;
5c7f4665 776 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
a3c76cdc 777 const Float_t kPoti = 12.1;
030b4415 778 // PDG code electron
779 const Int_t kPdgElectron = 11;
5c7f4665 780
781 // Set the maximum step size to a very large number for all
782 // neutral particles and those outside the driftvolume
783 gMC->SetMaxStep(kBig);
784
785 // Use only charged tracks
786 if (( gMC->TrackCharge() ) &&
5c7f4665 787 (!gMC->IsTrackDisappeared())) {
fe4da5cc 788
5c7f4665 789 // Inside a sensitive volume?
332e9569 790 drRegion = kFALSE;
791 amRegion = kFALSE;
792 cIdCurrent = gMC->CurrentVolName();
e6674585 793 if (cIdSensDr == cIdCurrent[1]) {
332e9569 794 drRegion = kTRUE;
795 }
e6674585 796 if (cIdSensAm == cIdCurrent[1]) {
332e9569 797 amRegion = kTRUE;
798 }
799 if (drRegion || amRegion) {
fe4da5cc 800
5c7f4665 801 // The hit coordinates and charge
802 gMC->TrackPosition(pos);
803 hits[0] = pos[0];
804 hits[1] = pos[1];
805 hits[2] = pos[2];
5c7f4665 806
851d3db9 807 // The sector number (0 - 17)
808 // The numbering goes clockwise and starts at y = 0
e15eb584 809 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
030b4415 810 if (phi < 90.0) {
811 phi = phi + 270.0;
812 }
813 else {
814 phi = phi - 90.0;
815 }
816 sec = ((Int_t) (phi / 20.0));
82bbf98a 817
332e9569 818 // The plane and chamber number
819 cIdChamber[0] = cIdCurrent[2];
820 cIdChamber[1] = cIdCurrent[3];
e644678a 821 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
a5cadd36 822 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
332e9569 823 pla = ((Int_t) idChamber % kNplan);
82bbf98a 824
5c7f4665 825 // Check on selected volumes
826 Int_t addthishit = 1;
5c7f4665 827
828 // Add this hit
829 if (addthishit) {
830
f73816f5 831 // The detector number
793ff80c 832 det = fGeometry->GetDetector(pla,cha,sec);
833
a328fff9 834 // Special hits only in the drift region
332e9569 835 if (drRegion) {
f73816f5 836
c61f1a66 837 // Create a track reference at the entrance and
838 // exit of each chamber that contain the
839 // momentum components of the particle
030b4415 840 if (gMC->IsTrackEntering() ||
841 gMC->IsTrackExiting()) {
f73816f5 842 gMC->TrackMomentum(mom);
5d12ce38 843 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
f73816f5 844 }
f73816f5 845 // Create the hits from TR photons
030b4415 846 if (fTR) {
847 CreateTRhit(det);
848 }
f73816f5 849
030b4415 850 }
f73816f5 851
852 // Calculate the energy of the delta-electrons
853 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
854 eDelta = TMath::Max(eDelta,0.0);
c4214bc0 855 // Generate the electron cluster size
030b4415 856 if (eDelta == 0.0) {
857 qTot = 0;
858 }
859 else {
860 qTot = ((Int_t) (eDelta / kWion) + 1);
861 }
f73816f5 862
030b4415 863 // Create a new dEdx hit
332e9569 864 if (drRegion) {
a328fff9 865 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 866 ,det
867 ,hits
868 ,qTot
869 ,kTRUE);
870 }
5c7f4665 871 else {
a328fff9 872 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 873 ,det
874 ,hits
875 ,qTot
876 ,kFALSE);
877 }
f73816f5 878
5c7f4665 879 // Calculate the maximum step size for the next tracking step
f73816f5 880 // Produce only one hit if Ekin is below cutoff
881 aMass = gMC->TrackMass();
882 if ((gMC->Etot() - aMass) > kEkinMinStep) {
883
884 // The energy loss according to Bethe Bloch
885 iPdg = TMath::Abs(gMC->TrackPid());
030b4415 886 if ((iPdg != kPdgElectron) ||
887 ((iPdg == kPdgElectron) &&
888 (pTot < kPTotMaxEl))) {
f73816f5 889 gMC->TrackMomentum(mom);
890 pTot = mom.Rho();
891 betaGamma = pTot / aMass;
892 pp = kPrim * BetheBloch(betaGamma);
893 // Take charge > 1 into account
894 charge = gMC->TrackCharge();
030b4415 895 if (TMath::Abs(charge) > 1) {
896 pp = pp * charge*charge;
897 }
898 }
899 else {
900 // Electrons above 20 Mev/c are at the plateau
901 pp = kPrim * kPlateau;
f73816f5 902 }
903
030b4415 904 if (pp > 0.0) {
905 do {
906 gMC->GetRandom()->RndmArray(1,random);
907 }
908 while ((random[0] == 1.0) ||
909 (random[0] == 0.0));
f73816f5 910 stepSize = - TMath::Log(random[0]) / pp;
911 gMC->SetMaxStep(stepSize);
030b4415 912 }
913
914 }
915
5c7f4665 916 }
030b4415 917
d3f347ff 918 }
030b4415 919
5c7f4665 920 }
030b4415 921
5c7f4665 922}
923
a328fff9 924//_____________________________________________________________________________
925void AliTRDv1::StepManagerFixedStep()
926{
927 //
928 // Slow simulator. Every charged track produces electron cluster as hits
929 // along its path across the drift volume. The step size is fixed in
930 // this version of the step manager.
931 //
932
933 Int_t pla = 0;
934 Int_t cha = 0;
935 Int_t sec = 0;
936 Int_t det = 0;
937 Int_t qTot;
938
939 Float_t hits[3];
940 Double_t eDep;
941
942 Bool_t drRegion = kFALSE;
943 Bool_t amRegion = kFALSE;
944
945 TString cIdCurrent;
946 TString cIdSensDr = "J";
947 TString cIdSensAm = "K";
948 Char_t cIdChamber[3];
949 cIdChamber[2] = 0;
950
030b4415 951 TLorentzVector pos;
952 TLorentzVector mom;
a328fff9 953
954 const Int_t kNplan = AliTRDgeometry::Nplan();
955 const Int_t kNcham = AliTRDgeometry::Ncham();
956 const Int_t kNdetsec = kNplan * kNcham;
957
030b4415 958 const Double_t kBig = 1.0e+12;
a328fff9 959
bc327ce2 960 const Float_t kWion = 23.53; // Ionization energy
a328fff9 961 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
962
963 // Set the maximum step size to a very large number for all
964 // neutral particles and those outside the driftvolume
965 gMC->SetMaxStep(kBig);
966
967 // If not charged track or already stopped or disappeared, just return.
968 if ((!gMC->TrackCharge()) ||
a328fff9 969 gMC->IsTrackDisappeared()) return;
970
971 // Inside a sensitive volume?
972 cIdCurrent = gMC->CurrentVolName();
973
974 if (cIdSensDr == cIdCurrent[1]) drRegion = kTRUE;
975 if (cIdSensAm == cIdCurrent[1]) amRegion = kTRUE;
976
030b4415 977 if ((!drRegion) &&
978 (!amRegion)) {
979 return;
980 }
a328fff9 981
982 // The hit coordinates and charge
983 gMC->TrackPosition(pos);
984 hits[0] = pos[0];
985 hits[1] = pos[1];
986 hits[2] = pos[2];
987
988 // The sector number (0 - 17)
989 // The numbering goes clockwise and starts at y = 0
990 Float_t phi = kRaddeg*TMath::ATan2(pos[0],pos[1]);
030b4415 991 if (phi < 90.0) {
992 phi = phi + 270.0;
993 }
994 else {
995 phi = phi - 90.0;
996 }
997 sec = ((Int_t) (phi / 20.0));
a328fff9 998
999 // The plane and chamber number
030b4415 1000 cIdChamber[0] = cIdCurrent[2];
1001 cIdChamber[1] = cIdCurrent[3];
a328fff9 1002 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
a5cadd36 1003 cha = kNcham - ((Int_t) idChamber / kNplan) - 1;
a328fff9 1004 pla = ((Int_t) idChamber % kNplan);
e0d47c25 1005
a328fff9 1006 // Check on selected volumes
1007 Int_t addthishit = 1;
a328fff9 1008
030b4415 1009 if (!addthishit) {
1010 return;
1011 }
a328fff9 1012
030b4415 1013 // The detector number
1014 det = fGeometry->GetDetector(pla,cha,sec);
1015
1016 // 0: InFlight 1:Entering 2:Exiting
1017 Int_t trkStat = 0;
a328fff9 1018
1019 // Special hits only in the drift region
1020 if (drRegion) {
1021
1022 // Create a track reference at the entrance and exit of each
1023 // chamber that contain the momentum components of the particle
1024
1025 if (gMC->IsTrackEntering()) {
1026 gMC->TrackMomentum(mom);
1027 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
1028 trkStat = 1;
1029 }
1030 if (gMC->IsTrackExiting()) {
1031 gMC->TrackMomentum(mom);
1032 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber());
1033 trkStat = 2;
1034 }
1035
1036 // Create the hits from TR photons
030b4415 1037 if (fTR) {
1038 CreateTRhit(det);
1039 }
a328fff9 1040
1041 }
1042
1043 // Calculate the charge according to GEANT Edep
1044 // Create a new dEdx hit
1045 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1046 qTot = (Int_t) (eDep / kWion);
c4214bc0 1047 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
030b4415 1048 ,det
1049 ,hits
1050 ,qTot
1051 ,drRegion);
a328fff9 1052
1053 // Set Maximum Step Size
1054 // Produce only one hit if Ekin is below cutoff
030b4415 1055 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1056 return;
1057 }
a328fff9 1058 gMC->SetMaxStep(fStepSize);
1059
1060}
1061
5c7f4665 1062//_____________________________________________________________________________
1063Double_t AliTRDv1::BetheBloch(Double_t bg)
1064{
1065 //
1066 // Parametrization of the Bethe-Bloch-curve
1067 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1068 //
1069
1070 // This parameters have been adjusted to averaged values from GEANT
f57bb418 1071 const Double_t kP1 = 7.17960e-02;
1072 const Double_t kP2 = 8.54196;
1073 const Double_t kP3 = 1.38065e-06;
1074 const Double_t kP4 = 5.30972;
1075 const Double_t kP5 = 2.83798;
5c7f4665 1076
f73816f5 1077 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1078 const Double_t kBgMin = 0.8;
1079 const Double_t kBBMax = 6.83298;
f73816f5 1080
1081 if (bg > kBgMin) {
030b4415 1082 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
5c7f4665 1083 Double_t aa = TMath::Power(yy,kP4);
030b4415 1084 Double_t bb = TMath::Power((1.0/bg),kP5);
5c7f4665 1085 bb = TMath::Log(kP3 + bb);
030b4415 1086 return ((kP2 - aa - bb) * kP1 / aa);
5c7f4665 1087 }
f73816f5 1088 else {
1089 return kBBMax;
1090 }
d3f347ff 1091
fe4da5cc 1092}
5c7f4665 1093
a328fff9 1094//_____________________________________________________________________________
c4214bc0 1095Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
a328fff9 1096{
1097 //
1098 // Return dN/dx (number of primary collisions per centimeter)
1099 // for given beta*gamma factor.
1100 //
1101 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1102 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1103 // This must be used as a set with IntSpecGeant.
1104 //
1105
030b4415 1106 Int_t i = 0;
a328fff9 1107
030b4415 1108 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1109 , 1.800000, 2.000000, 2.500000, 3.000000
1110 , 4.000000, 7.000000, 10.000000, 20.000000
1111 , 40.000000, 70.000000, 100.000000, 300.000000
1112 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
a328fff9 1113
030b4415 1114 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1115 , 22.734999, 21.411915, 19.934095, 19.449375
1116 , 19.344431, 20.185553, 21.027925, 22.912676
1117 , 24.933352, 26.504053, 27.387468, 29.566597
1118 , 30.353779, 30.787134, 31.129285, 31.157350 };
1119
1120 // Betagamma to gamma
1121 Double_t g = TMath::Sqrt(1.0 + bg*bg);
a328fff9 1122
1123 // Find the index just before the point we need.
030b4415 1124 for (i = 0; i < 18; i++) {
1125 if ((arrG[i] < g) &&
1126 (arrG[i+1] > g)) {
a328fff9 1127 break;
030b4415 1128 }
1129 }
a328fff9 1130
1131 // Simple interpolation.
030b4415 1132 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1133 * (g - arrG[i]) + arrNC[i];
a328fff9 1134
030b4415 1135 return pp;
a328fff9 1136
1137}
1138
5c7f4665 1139//_____________________________________________________________________________
1140Double_t Ermilova(Double_t *x, Double_t *)
1141{
1142 //
1143 // Calculates the delta-ray energy distribution according to Ermilova.
1144 // Logarithmic scale !
1145 //
1146
1147 Double_t energy;
1148 Double_t dpos;
1149 Double_t dnde;
1150
030b4415 1151 Int_t pos1;
1152 Int_t pos2;
5c7f4665 1153
8230f242 1154 const Int_t kNv = 31;
5c7f4665 1155
030b4415 1156 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1157 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1158 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1159 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1160 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1161 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1162 , 11.5129 };
1163
1164 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1165 , 20.9, 20.8, 20.0, 16.0, 11.0
1166 , 8.0, 6.0, 5.2, 4.6, 4.0
1167 , 3.5, 3.0, 1.4, 0.67, 0.44
1168 , 0.3, 0.18, 0.12, 0.08, 0.056
1169 , 0.04, 0.023, 0.015, 0.011, 0.01
1170 , 0.004 };
5c7f4665 1171
1172 energy = x[0];
1173
1174 // Find the position
030b4415 1175 pos1 = 0;
1176 pos2 = 0;
5c7f4665 1177 dpos = 0;
1178 do {
1179 dpos = energy - vxe[pos2++];
1180 }
1181 while (dpos > 0);
1182 pos2--;
030b4415 1183 if (pos2 > kNv) {
1184 pos2 = kNv - 1;
1185 }
5c7f4665 1186 pos1 = pos2 - 1;
1187
1188 // Differentiate between the sampling points
1189 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1190
1191 return dnde;
1192
1193}
a328fff9 1194
1195//_____________________________________________________________________________
1196Double_t IntSpecGeant(Double_t *x, Double_t *)
1197{
1198 //
1199 // Integrated spectrum from Geant3
1200 //
1201
96efaf83 1202 const Int_t npts = 83;
030b4415 1203 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1204 , 2.672067, 2.813299, 3.015059, 3.216819
1205 , 3.418579, 3.620338, 3.868209, 3.920198
1206 , 3.978284, 4.063923, 4.186264, 4.308605
1207 , 4.430946, 4.553288, 4.724261, 4.837736
1208 , 4.999842, 5.161949, 5.324056, 5.486163
1209 , 5.679688, 5.752998, 5.857728, 5.962457
1210 , 6.067185, 6.171914, 6.315653, 6.393674
1211 , 6.471694, 6.539689, 6.597658, 6.655627
1212 , 6.710957, 6.763648, 6.816338, 6.876198
1213 , 6.943227, 7.010257, 7.106285, 7.252151
1214 , 7.460531, 7.668911, 7.877290, 8.085670
1215 , 8.302979, 8.353585, 8.413120, 8.483500
1216 , 8.541030, 8.592857, 8.668865, 8.820485
1217 , 9.037086, 9.253686, 9.470286, 9.686887
1218 , 9.930838, 9.994655, 10.085822, 10.176990
1219 , 10.268158, 10.359325, 10.503614, 10.627565
1220 , 10.804637, 10.981709, 11.158781, 11.335854
1221 , 11.593397, 11.781165, 12.049404, 12.317644
1222 , 12.585884, 12.854123, 14.278421, 16.975889
1223 , 20.829416, 24.682943, 28.536469 };
1224
1225 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1226 , 9.1601500, 8.206670, 6.919630, 5.655430
1227 , 4.6221300, 3.777610, 3.019560, 2.591950
1228 , 2.5414600, 2.712920, 3.327460, 4.928240
1229 , 7.6185300, 10.966700, 12.225800, 8.094750
1230 , 3.3586900, 1.553650, 1.209600, 1.263840
1231 , 1.3241100, 1.312140, 1.255130, 1.165770
1232 , 1.0594500, 0.945450, 0.813231, 0.699837
1233 , 0.6235580, 2.260990, 2.968350, 2.240320
1234 , 1.7988300, 1.553300, 1.432070, 1.535520
1235 , 1.4429900, 1.247990, 1.050750, 0.829549
1236 , 0.5900280, 0.395897, 0.268741, 0.185320
1237 , 0.1292120, 0.103545, 0.0949525, 0.101535
1238 , 0.1276380, 0.134216, 0.123816, 0.104557
1239 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1240 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1241 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1242 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1243 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1244 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1245 , 3.63304e-06, 0.0000000, 0.0000000 };
1246
1247 Int_t i;
a328fff9 1248 Double_t energy = x[0];
a328fff9 1249
030b4415 1250 for (i = 0; i < npts; i++) {
1251 if (energy < arre[i]) {
1252 break;
1253 }
1254 }
a328fff9 1255
030b4415 1256 if (i == 0) {
1257 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");
1258 }
a328fff9 1259
f57bb418 1260 return arrdnde[i];
a328fff9 1261
1262}