1 /**************************************************************************
2 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
4 * Author: The ALICE Off-line Project. *
5 * Contributors are mentioned in the code where appropriate. *
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 **************************************************************************/
18 ////////////////////////////////////////////////////////////////////////////
20 // Transition Radiation Detector version 1 -- slow simulator //
22 ////////////////////////////////////////////////////////////////////////////
27 #include <TLorentzVector.h>
31 #include <TVirtualMC.h>
32 #include <TGeoManager.h>
33 #include <TGeoPhysicalNode.h>
37 #include "AliTrackReference.h"
41 #include "AliTRDgeometry.h"
42 #include "AliTRDhit.h"
43 #include "AliTRDsimTR.h"
48 //_____________________________________________________________________________
53 ,fTypeOfStepManager(0)
61 // Default constructor
66 //_____________________________________________________________________________
67 AliTRDv1::AliTRDv1(const char *name, const char *title)
71 ,fTypeOfStepManager(2)
79 // Standard constructor for Transition Radiation Detector version 1
82 SetBufferSize(128000);
86 //_____________________________________________________________________________
90 // AliTRDv1 destructor
110 //_____________________________________________________________________________
111 void AliTRDv1::AddAlignableVolumes() const
114 // Create entries for alignable volumes associating the symbolic volume
115 // name with the corresponding volume path. Needs to be syncronized with
116 // eventual changes in the geometry.
122 TString vpStr = "ALIC_1/B077_1/BSEGMO";
123 TString vpApp1 = "_1/BTRD";
124 TString vpApp2 = "_1";
125 TString vpApp3 = "/UTR1_1/UTS1_1/UTI1_1/UT";
127 TString snStr = "TRD/sm";
128 TString snApp1 = "/st";
129 TString snApp2 = "/pl";
133 // The symbolic names are: TRD/sm00
137 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
146 symName += Form("%02d",isect);
148 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
153 // The readout chambers
154 // The symbolic names are: TRD/sm00/st0/pl0
158 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
159 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
160 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
162 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
170 volPath += Form("%02d",idet);
174 symName += Form("%02d",isect);
180 TGeoPNEntry *alignableEntry =
181 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
183 // Add the tracking to local matrix following the TPC example
185 if (alignableEntry) {
186 const char *path = alignableEntry->GetTitle();
187 if (!gGeoManager->cd(path)) {
188 AliFatal(Form("Volume path %s not valid!",path));
190 TGeoHMatrix *globMatrix = gGeoManager->GetCurrentMatrix();
191 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
192 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
193 t2lMatrix->RotateZ(sectorAngle);
194 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
195 alignableEntry->SetMatrix(t2lMatrix);
198 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
206 //_____________________________________________________________________________
207 void AliTRDv1::CreateGeometry()
210 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
211 // This version covers the full azimuth.
214 // Check that FRAME is there otherwise we have no place where to put the TRD
215 AliModule* frame = gAlice->GetModule("FRAME");
217 AliError("TRD needs FRAME to be present\n");
221 // Define the chambers
222 AliTRD::CreateGeometry();
226 //_____________________________________________________________________________
227 void AliTRDv1::CreateMaterials()
230 // Create materials for the Transition Radiation Detector version 1
233 AliTRD::CreateMaterials();
237 //_____________________________________________________________________________
238 void AliTRDv1::CreateTRhit(Int_t det)
241 // Creates an electron cluster from a TR photon.
242 // The photon is assumed to be created a the end of the radiator. The
243 // distance after which it deposits its energy takes into account the
244 // absorbtion of the entrance window and of the gas mixture in drift
249 const Float_t kWion = 23.53;
251 // Maximum number of TR photons per track
252 const Int_t kNTR = 50;
261 gMC->TrackMomentum(mom);
262 Float_t pTot = mom.Rho();
263 fTR->CreatePhotons(11,pTot,nTR,eTR);
265 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
268 // Loop through the TR photons
269 for (Int_t iTR = 0; iTR < nTR; iTR++) {
271 Float_t energyMeV = eTR[iTR] * 0.001;
272 Float_t energyeV = eTR[iTR] * 1000.0;
273 Float_t absLength = 0.0;
276 // Take the absorbtion in the entrance window into account
277 Double_t muMy = fTR->GetMuMy(energyMeV);
278 sigma = muMy * fFoilDensity;
280 absLength = gRandom->Exp(1.0/sigma);
281 if (absLength < AliTRDgeometry::MyThick()) {
289 // The absorbtion cross sections in the drift gas
290 // Gas-mixture (Xe/CO2)
291 Double_t muXe = fTR->GetMuXe(energyMeV);
292 Double_t muCO = fTR->GetMuCO(energyMeV);
293 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
295 // The distance after which the energy of the TR photon
298 absLength = gRandom->Exp(1.0/sigma);
299 if (absLength > (AliTRDgeometry::DrThick()
300 + AliTRDgeometry::AmThick())) {
308 // The position of the absorbtion
310 gMC->TrackPosition(pos);
311 posHit[0] = pos[0] + mom[0] / pTot * absLength;
312 posHit[1] = pos[1] + mom[1] / pTot * absLength;
313 posHit[2] = pos[2] + mom[2] / pTot * absLength;
316 Int_t q = ((Int_t) (energyeV / kWion));
318 // Add the hit to the array. TR photon hits are marked
319 // by negative charge
320 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
324 ,gMC->TrackTime()*1.0e06
331 //_____________________________________________________________________________
332 void AliTRDv1::Init()
335 // Initialise Transition Radiation Detector after geometry has been built.
340 AliDebug(1,"Slow simulator\n");
342 // Switch on TR simulation as default
344 AliInfo("TR simulation off");
347 fTR = new AliTRDsimTR();
350 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
351 const Float_t kPoti = 12.1;
352 // Maximum energy (50 keV);
353 const Float_t kEend = 50000.0;
354 // Ermilova distribution for the delta-ray spectrum
355 Float_t poti = TMath::Log(kPoti);
356 Float_t eEnd = TMath::Log(kEend);
358 // Ermilova distribution for the delta-ray spectrum
359 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
361 // Geant3 distribution for the delta-ray spectrum
362 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
364 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
368 //_____________________________________________________________________________
369 void AliTRDv1::StepManager()
372 // Slow simulator. Every charged track produces electron cluster as hits
373 // along its path across the drift volume.
376 switch (fTypeOfStepManager) {
378 StepManagerErmilova();
384 StepManagerFixedStep();
387 AliWarning("Not a valid Step Manager.");
392 //_____________________________________________________________________________
393 void AliTRDv1::SelectStepManager(Int_t t)
396 // Selects a step manager type:
399 // 2 - Fixed step size
402 fTypeOfStepManager = t;
403 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
407 //_____________________________________________________________________________
408 void AliTRDv1::StepManagerGeant()
411 // Slow simulator. Every charged track produces electron cluster as hits
412 // along its path across the drift volume. The step size is set acording
413 // to Bethe-Bloch. The energy distribution of the delta electrons follows
414 // a spectrum taken from Geant3.
416 // Version by A. Bercuci
434 Double_t stepSize = 0;
436 Bool_t drRegion = kFALSE;
437 Bool_t amRegion = kFALSE;
444 TString cIdSensDr = "J";
445 TString cIdSensAm = "K";
446 Char_t cIdChamber[3];
454 const Int_t kNplan = AliTRDgeometry::Nplan();
455 const Int_t kNcham = AliTRDgeometry::Ncham();
456 const Int_t kNdetsec = kNplan * kNcham;
458 const Double_t kBig = 1.0e+12; // Infinitely big
459 const Float_t kWion = 23.53; // Ionization energy
460 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
462 // Minimum energy for the step size adjustment
463 const Float_t kEkinMinStep = 1.0e-5;
464 // energy threshold for production of delta electrons
465 const Float_t kECut = 1.0e4;
466 // Parameters entering the parametrized range for delta electrons
467 const Float_t kRa = 5.37e-4;
468 const Float_t kRb = 0.9815;
469 const Float_t kRc = 3.123e-3;
470 // Gas density -> To be made user adjustable !
471 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
472 const Float_t kRho = 0.004945 ;
474 // Plateau value of the energy-loss for electron in xenon
475 // The averaged value (26/3/99)
476 const Float_t kPlateau = 1.55;
477 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
478 const Float_t kPrim = 19.34;
479 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
480 const Float_t kPoti = 12.1;
482 const Int_t kPdgElectron = 11;
484 // Set the maximum step size to a very large number for all
485 // neutral particles and those outside the driftvolume
486 gMC->SetMaxStep(kBig);
488 // Use only charged tracks
489 if (( gMC->TrackCharge() ) &&
490 (!gMC->IsTrackDisappeared())) {
492 // Inside a sensitive volume?
495 cIdCurrent = gMC->CurrentVolName();
496 if (cIdSensDr == cIdCurrent[1]) {
499 if (cIdSensAm == cIdCurrent[1]) {
502 if (drRegion || amRegion) {
504 // The hit coordinates and charge
505 gMC->TrackPosition(pos);
510 // The sector number (0 - 17), according to standard coordinate system
511 cIdPath = gGeoManager->GetPath();
512 cIdSector[0] = cIdPath[21];
513 cIdSector[1] = cIdPath[22];
514 sec = atoi(cIdSector);
516 // The plane and chamber number
517 cIdChamber[0] = cIdCurrent[2];
518 cIdChamber[1] = cIdCurrent[3];
519 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
520 cha = ((Int_t) idChamber / kNplan);
521 pla = ((Int_t) idChamber % kNplan);
523 // The detector number
524 det = fGeometry->GetDetector(pla,cha,sec);
526 // Special hits only in the drift region
528 (gMC->IsTrackEntering())) {
530 // Create a track reference at the entrance of each
531 // chamber that contains the momentum components of the particle
532 gMC->TrackMomentum(mom);
533 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
535 // Create the hits from TR photons if electron/positron is
536 // entering the drift volume
538 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
543 else if ((amRegion) &&
544 (gMC->IsTrackExiting())) {
546 // Create a track reference at the exit of each
547 // chamber that contains the momentum components of the particle
548 gMC->TrackMomentum(mom);
549 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
553 // Calculate the energy of the delta-electrons
554 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
555 // take into account correlation with the underlying GEANT tracking
557 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
559 // determine the most significant process (last on the processes list)
560 // which caused this hit
561 gMC->StepProcesses(processes);
562 Int_t nofprocesses = processes.GetSize();
568 pid = processes[nofprocesses-1];
571 // Generate Edep according to GEANT parametrisation
572 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
573 eDelta = TMath::Max(eDelta,0.0);
574 Float_t prRange = 0.0;
575 Float_t range = gMC->TrackLength() - fTrackLength0;
576 // merge GEANT tracker information with locally cooked one
577 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
579 if (eDelta >= kECut) {
580 prRange = kRa * eDelta * 0.001
581 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
582 if (prRange >= (3.7 - range)) {
588 if (eDelta < kECut) {
592 prRange = kRa * eDelta * 0.001
593 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
594 if (prRange >= ((AliTRDgeometry::DrThick()
595 + AliTRDgeometry::AmThick()) - range)) {
611 // Generate the electron cluster size
614 qTot = ((Int_t) (eDelta / kWion) + 1);
616 // Create a new dEdx hit
617 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
621 ,gMC->TrackTime()*1.0e06
626 // Calculate the maximum step size for the next tracking step
627 // Produce only one hit if Ekin is below cutoff
628 aMass = gMC->TrackMass();
629 if ((gMC->Etot() - aMass) > kEkinMinStep) {
631 // The energy loss according to Bethe Bloch
632 iPdg = TMath::Abs(gMC->TrackPid());
633 if ((iPdg != kPdgElectron) ||
634 ((iPdg == kPdgElectron) &&
635 (pTot < kPTotMaxEl))) {
636 gMC->TrackMomentum(mom);
638 betaGamma = pTot / aMass;
639 pp = BetheBlochGeant(betaGamma);
640 // Take charge > 1 into account
641 charge = gMC->TrackCharge();
642 if (TMath::Abs(charge) > 1) {
643 pp = pp * charge*charge;
647 // Electrons above 20 Mev/c are at the plateau
648 pp = kPrim * kPlateau;
653 nsteps = gRandom->Poisson(pp);
655 stepSize = 1.0 / nsteps;
656 gMC->SetMaxStep(stepSize);
666 //_____________________________________________________________________________
667 void AliTRDv1::StepManagerErmilova()
670 // Slow simulator. Every charged track produces electron cluster as hits
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.
694 Bool_t drRegion = kFALSE;
695 Bool_t amRegion = kFALSE;
702 TString cIdSensDr = "J";
703 TString cIdSensAm = "K";
704 Char_t cIdChamber[3];
710 const Int_t kNplan = AliTRDgeometry::Nplan();
711 const Int_t kNcham = AliTRDgeometry::Ncham();
712 const Int_t kNdetsec = kNplan * kNcham;
714 const Double_t kBig = 1.0e+12; // Infinitely big
715 const Float_t kWion = 23.53; // Ionization energy
716 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
718 // Minimum energy for the step size adjustment
719 const Float_t kEkinMinStep = 1.0e-5;
721 // Plateau value of the energy-loss for electron in xenon
722 // The averaged value (26/3/99)
723 const Float_t kPlateau = 1.55;
724 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
725 const Float_t kPrim = 48.0;
726 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
727 const Float_t kPoti = 12.1;
729 const Int_t kPdgElectron = 11;
731 // Set the maximum step size to a very large number for all
732 // neutral particles and those outside the driftvolume
733 gMC->SetMaxStep(kBig);
735 // Use only charged tracks
736 if (( gMC->TrackCharge() ) &&
737 (!gMC->IsTrackDisappeared())) {
739 // Inside a sensitive volume?
742 cIdCurrent = gMC->CurrentVolName();
743 if (cIdSensDr == cIdCurrent[1]) {
746 if (cIdSensAm == cIdCurrent[1]) {
749 if (drRegion || amRegion) {
751 // The hit coordinates and charge
752 gMC->TrackPosition(pos);
757 // The sector number (0 - 17), according to standard coordinate system
758 cIdPath = gGeoManager->GetPath();
759 cIdSector[0] = cIdPath[21];
760 cIdSector[1] = cIdPath[22];
761 sec = atoi(cIdSector);
763 // The plane and chamber number
764 cIdChamber[0] = cIdCurrent[2];
765 cIdChamber[1] = cIdCurrent[3];
766 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
767 cha = ((Int_t) idChamber / kNplan);
768 pla = ((Int_t) idChamber % kNplan);
770 // The detector number
771 det = fGeometry->GetDetector(pla,cha,sec);
773 // Special hits only in the drift region
775 (gMC->IsTrackEntering())) {
777 // Create a track reference at the entrance of each
778 // chamber that contains the momentum components of the particle
779 gMC->TrackMomentum(mom);
780 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
782 // Create the hits from TR photons if electron/positron is
783 // entering the drift volume
785 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
790 else if ((amRegion) &&
791 (gMC->IsTrackExiting())) {
793 // Create a track reference at the exit of each
794 // chamber that contains the momentum components of the particle
795 gMC->TrackMomentum(mom);
796 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
800 // Calculate the energy of the delta-electrons
801 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
802 eDelta = TMath::Max(eDelta,0.0);
804 // Generate the electron cluster size
807 qTot = ((Int_t) (eDelta / kWion) + 1);
809 // Create a new dEdx hit
811 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
815 ,gMC->TrackTime()*1.0e06
819 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
823 ,gMC->TrackTime()*1.0e06
829 // Calculate the maximum step size for the next tracking step
830 // Produce only one hit if Ekin is below cutoff
831 aMass = gMC->TrackMass();
832 if ((gMC->Etot() - aMass) > kEkinMinStep) {
834 // The energy loss according to Bethe Bloch
835 iPdg = TMath::Abs(gMC->TrackPid());
836 if ((iPdg != kPdgElectron) ||
837 ((iPdg == kPdgElectron) &&
838 (pTot < kPTotMaxEl))) {
839 gMC->TrackMomentum(mom);
841 betaGamma = pTot / aMass;
842 pp = kPrim * BetheBloch(betaGamma);
843 // Take charge > 1 into account
844 charge = gMC->TrackCharge();
845 if (TMath::Abs(charge) > 1) {
846 pp = pp * charge*charge;
850 // Electrons above 20 Mev/c are at the plateau
851 pp = kPrim * kPlateau;
856 gMC->GetRandom()->RndmArray(1,random);
858 while ((random[0] == 1.0) ||
860 stepSize = - TMath::Log(random[0]) / pp;
861 gMC->SetMaxStep(stepSize);
872 //_____________________________________________________________________________
873 void AliTRDv1::StepManagerFixedStep()
876 // Slow simulator. Every charged track produces electron cluster as hits
877 // along its path across the drift volume. The step size is fixed in
878 // this version of the step manager.
882 const Int_t kPdgElectron = 11;
893 Bool_t drRegion = kFALSE;
894 Bool_t amRegion = kFALSE;
901 TString cIdSensDr = "J";
902 TString cIdSensAm = "K";
903 Char_t cIdChamber[3];
909 const Int_t kNplan = AliTRDgeometry::Nplan();
910 const Int_t kNcham = AliTRDgeometry::Ncham();
911 const Int_t kNdetsec = kNplan * kNcham;
913 const Double_t kBig = 1.0e+12;
915 const Float_t kWion = 23.53; // Ionization energy
916 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
918 // Set the maximum step size to a very large number for all
919 // neutral particles and those outside the driftvolume
920 gMC->SetMaxStep(kBig);
922 // If not charged track or already stopped or disappeared, just return.
923 if ((!gMC->TrackCharge()) ||
924 gMC->IsTrackDisappeared()) {
928 // Inside a sensitive volume?
929 cIdCurrent = gMC->CurrentVolName();
931 if (cIdSensDr == cIdCurrent[1]) {
934 if (cIdSensAm == cIdCurrent[1]) {
943 // The hit coordinates and charge
944 gMC->TrackPosition(pos);
949 // The sector number (0 - 17), according to standard coordinate system
950 cIdPath = gGeoManager->GetPath();
951 cIdSector[0] = cIdPath[21];
952 cIdSector[1] = cIdPath[22];
953 sec = atoi(cIdSector);
955 // The plane and chamber number
956 cIdChamber[0] = cIdCurrent[2];
957 cIdChamber[1] = cIdCurrent[3];
958 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
959 cha = ((Int_t) idChamber / kNplan);
960 pla = ((Int_t) idChamber % kNplan);
962 // The detector number
963 det = fGeometry->GetDetector(pla,cha,sec);
965 // 0: InFlight 1:Entering 2:Exiting
968 // Special hits only in the drift region
970 (gMC->IsTrackEntering())) {
972 // Create a track reference at the entrance of each
973 // chamber that contains the momentum components of the particle
974 gMC->TrackMomentum(mom);
975 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
978 // Create the hits from TR photons if electron/positron is
979 // entering the drift volume
981 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
986 else if ((amRegion) &&
987 (gMC->IsTrackExiting())) {
989 // Create a track reference at the exit of each
990 // chamber that contains the momentum components of the particle
991 gMC->TrackMomentum(mom);
992 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
997 // Calculate the charge according to GEANT Edep
998 // Create a new dEdx hit
999 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1000 qTot = (Int_t) (eDep / kWion);
1003 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1007 ,gMC->TrackTime()*1.0e06
1011 // Set Maximum Step Size
1012 // Produce only one hit if Ekin is below cutoff
1013 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1016 gMC->SetMaxStep(fStepSize);
1020 //_____________________________________________________________________________
1021 Double_t AliTRDv1::BetheBloch(Double_t bg)
1024 // Parametrization of the Bethe-Bloch-curve
1025 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1028 // This parameters have been adjusted to averaged values from GEANT
1029 const Double_t kP1 = 7.17960e-02;
1030 const Double_t kP2 = 8.54196;
1031 const Double_t kP3 = 1.38065e-06;
1032 const Double_t kP4 = 5.30972;
1033 const Double_t kP5 = 2.83798;
1035 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1036 const Double_t kBgMin = 0.8;
1037 const Double_t kBBMax = 6.83298;
1040 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
1041 Double_t aa = TMath::Power(yy,kP4);
1042 Double_t bb = TMath::Power((1.0/bg),kP5);
1043 bb = TMath::Log(kP3 + bb);
1044 return ((kP2 - aa - bb) * kP1 / aa);
1052 //_____________________________________________________________________________
1053 Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
1056 // Return dN/dx (number of primary collisions per centimeter)
1057 // for given beta*gamma factor.
1059 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1060 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1061 // This must be used as a set with IntSpecGeant.
1066 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1067 , 1.800000, 2.000000, 2.500000, 3.000000
1068 , 4.000000, 7.000000, 10.000000, 20.000000
1069 , 40.000000, 70.000000, 100.000000, 300.000000
1070 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
1072 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1073 , 22.734999, 21.411915, 19.934095, 19.449375
1074 , 19.344431, 20.185553, 21.027925, 22.912676
1075 , 24.933352, 26.504053, 27.387468, 29.566597
1076 , 30.353779, 30.787134, 31.129285, 31.157350 };
1078 // Betagamma to gamma
1079 Double_t g = TMath::Sqrt(1.0 + bg*bg);
1081 // Find the index just before the point we need.
1082 for (i = 0; i < 18; i++) {
1083 if ((arrG[i] < g) &&
1089 // Simple interpolation.
1090 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1091 * (g - arrG[i]) + arrNC[i];
1097 //_____________________________________________________________________________
1098 Double_t Ermilova(Double_t *x, Double_t *)
1101 // Calculates the delta-ray energy distribution according to Ermilova.
1102 // Logarithmic scale !
1112 const Int_t kNv = 31;
1114 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1115 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1116 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1117 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1118 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1119 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1122 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1123 , 20.9, 20.8, 20.0, 16.0, 11.0
1124 , 8.0, 6.0, 5.2, 4.6, 4.0
1125 , 3.5, 3.0, 1.4, 0.67, 0.44
1126 , 0.3, 0.18, 0.12, 0.08, 0.056
1127 , 0.04, 0.023, 0.015, 0.011, 0.01
1132 // Find the position
1137 dpos = energy - vxe[pos2++];
1146 // Differentiate between the sampling points
1147 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1153 //_____________________________________________________________________________
1154 Double_t IntSpecGeant(Double_t *x, Double_t *)
1157 // Integrated spectrum from Geant3
1160 const Int_t npts = 83;
1161 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1162 , 2.672067, 2.813299, 3.015059, 3.216819
1163 , 3.418579, 3.620338, 3.868209, 3.920198
1164 , 3.978284, 4.063923, 4.186264, 4.308605
1165 , 4.430946, 4.553288, 4.724261, 4.837736
1166 , 4.999842, 5.161949, 5.324056, 5.486163
1167 , 5.679688, 5.752998, 5.857728, 5.962457
1168 , 6.067185, 6.171914, 6.315653, 6.393674
1169 , 6.471694, 6.539689, 6.597658, 6.655627
1170 , 6.710957, 6.763648, 6.816338, 6.876198
1171 , 6.943227, 7.010257, 7.106285, 7.252151
1172 , 7.460531, 7.668911, 7.877290, 8.085670
1173 , 8.302979, 8.353585, 8.413120, 8.483500
1174 , 8.541030, 8.592857, 8.668865, 8.820485
1175 , 9.037086, 9.253686, 9.470286, 9.686887
1176 , 9.930838, 9.994655, 10.085822, 10.176990
1177 , 10.268158, 10.359325, 10.503614, 10.627565
1178 , 10.804637, 10.981709, 11.158781, 11.335854
1179 , 11.593397, 11.781165, 12.049404, 12.317644
1180 , 12.585884, 12.854123, 14.278421, 16.975889
1181 , 20.829416, 24.682943, 28.536469 };
1183 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1184 , 9.1601500, 8.206670, 6.919630, 5.655430
1185 , 4.6221300, 3.777610, 3.019560, 2.591950
1186 , 2.5414600, 2.712920, 3.327460, 4.928240
1187 , 7.6185300, 10.966700, 12.225800, 8.094750
1188 , 3.3586900, 1.553650, 1.209600, 1.263840
1189 , 1.3241100, 1.312140, 1.255130, 1.165770
1190 , 1.0594500, 0.945450, 0.813231, 0.699837
1191 , 0.6235580, 2.260990, 2.968350, 2.240320
1192 , 1.7988300, 1.553300, 1.432070, 1.535520
1193 , 1.4429900, 1.247990, 1.050750, 0.829549
1194 , 0.5900280, 0.395897, 0.268741, 0.185320
1195 , 0.1292120, 0.103545, 0.0949525, 0.101535
1196 , 0.1276380, 0.134216, 0.123816, 0.104557
1197 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1198 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1199 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1200 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1201 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1202 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1203 , 3.63304e-06, 0.0000000, 0.0000000 };
1206 Double_t energy = x[0];
1208 for (i = 0; i < npts; i++) {
1209 if (energy < arre[i]) {
1215 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");