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