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 vpApp3a = "/UTR1_1/UTS1_1/UTI1_1/UT";
126 TString vpApp3b = "/UTR2_1/UTS2_1/UTI2_1/UT";
127 TString vpApp3c = "/UTR3_1/UTS3_1/UTI3_1/UT";
129 TString snStr = "TRD/sm";
130 TString snApp1 = "/st";
131 TString snApp2 = "/pl";
135 // The symbolic names are: TRD/sm00
139 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
148 symName += Form("%02d",isect);
150 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
155 // The readout chambers
156 // The symbolic names are: TRD/sm00/st0/pl0
160 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
162 if (fGeometry->GetSMstatus(isect) == 0) continue;
164 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
165 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
167 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
190 volPath += Form("%02d",idet);
194 symName += Form("%02d",isect);
200 TGeoPNEntry *alignableEntry =
201 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
203 // Add the tracking to local matrix following the TPC example
204 if (alignableEntry) {
205 const char *path = alignableEntry->GetTitle();
206 if (!gGeoManager->cd(path)) {
207 AliFatal(Form("Volume path %s not valid!",path));
209 // Is this correct still????
210 TGeoHMatrix *globMatrix = gGeoManager->GetCurrentMatrix();
211 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
212 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
213 t2lMatrix->RotateZ(sectorAngle);
214 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
215 alignableEntry->SetMatrix(t2lMatrix);
218 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
227 //_____________________________________________________________________________
228 void AliTRDv1::CreateGeometry()
231 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
232 // This version covers the full azimuth.
235 // Check that FRAME is there otherwise we have no place where to put the TRD
236 AliModule* frame = gAlice->GetModule("FRAME");
238 AliError("TRD needs FRAME to be present\n");
242 // Define the chambers
243 AliTRD::CreateGeometry();
247 //_____________________________________________________________________________
248 void AliTRDv1::CreateMaterials()
251 // Create materials for the Transition Radiation Detector version 1
254 AliTRD::CreateMaterials();
258 //_____________________________________________________________________________
259 void AliTRDv1::CreateTRhit(Int_t det)
262 // Creates an electron cluster from a TR photon.
263 // The photon is assumed to be created a the end of the radiator. The
264 // distance after which it deposits its energy takes into account the
265 // absorbtion of the entrance window and of the gas mixture in drift
270 const Float_t kWion = 23.53;
272 // Maximum number of TR photons per track
273 const Int_t kNTR = 50;
282 gMC->TrackMomentum(mom);
283 Float_t pTot = mom.Rho();
284 fTR->CreatePhotons(11,pTot,nTR,eTR);
286 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
289 // Loop through the TR photons
290 for (Int_t iTR = 0; iTR < nTR; iTR++) {
292 Float_t energyMeV = eTR[iTR] * 0.001;
293 Float_t energyeV = eTR[iTR] * 1000.0;
294 Float_t absLength = 0.0;
297 // Take the absorbtion in the entrance window into account
298 Double_t muMy = fTR->GetMuMy(energyMeV);
299 sigma = muMy * fFoilDensity;
301 absLength = gRandom->Exp(1.0/sigma);
302 if (absLength < AliTRDgeometry::MyThick()) {
310 // The absorbtion cross sections in the drift gas
311 // Gas-mixture (Xe/CO2)
312 Double_t muXe = fTR->GetMuXe(energyMeV);
313 Double_t muCO = fTR->GetMuCO(energyMeV);
314 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
316 // The distance after which the energy of the TR photon
319 absLength = gRandom->Exp(1.0/sigma);
320 if (absLength > (AliTRDgeometry::DrThick()
321 + AliTRDgeometry::AmThick())) {
329 // The position of the absorbtion
331 gMC->TrackPosition(pos);
332 posHit[0] = pos[0] + mom[0] / pTot * absLength;
333 posHit[1] = pos[1] + mom[1] / pTot * absLength;
334 posHit[2] = pos[2] + mom[2] / pTot * absLength;
337 Int_t q = ((Int_t) (energyeV / kWion));
339 // Add the hit to the array. TR photon hits are marked
340 // by negative charge
341 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
345 ,gMC->TrackTime()*1.0e06
352 //_____________________________________________________________________________
353 void AliTRDv1::Init()
356 // Initialise Transition Radiation Detector after geometry has been built.
361 AliDebug(1,"Slow simulator\n");
363 // Switch on TR simulation as default
365 AliInfo("TR simulation off");
368 fTR = new AliTRDsimTR();
371 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
372 const Float_t kPoti = 12.1;
373 // Maximum energy (50 keV);
374 const Float_t kEend = 50000.0;
375 // Ermilova distribution for the delta-ray spectrum
376 Float_t poti = TMath::Log(kPoti);
377 Float_t eEnd = TMath::Log(kEend);
379 // Ermilova distribution for the delta-ray spectrum
380 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
382 // Geant3 distribution for the delta-ray spectrum
383 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
385 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
389 //_____________________________________________________________________________
390 void AliTRDv1::StepManager()
393 // Slow simulator. Every charged track produces electron cluster as hits
394 // along its path across the drift volume.
397 switch (fTypeOfStepManager) {
399 StepManagerErmilova();
405 StepManagerFixedStep();
408 AliWarning("Not a valid Step Manager.");
413 //_____________________________________________________________________________
414 void AliTRDv1::SelectStepManager(Int_t t)
417 // Selects a step manager type:
420 // 2 - Fixed step size
423 fTypeOfStepManager = t;
424 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
428 //_____________________________________________________________________________
429 void AliTRDv1::StepManagerGeant()
432 // Slow simulator. Every charged track produces electron cluster as hits
433 // along its path across the drift volume. The step size is set acording
434 // to Bethe-Bloch. The energy distribution of the delta electrons follows
435 // a spectrum taken from Geant3.
437 // Version by A. Bercuci
455 Double_t stepSize = 0;
457 Bool_t drRegion = kFALSE;
458 Bool_t amRegion = kFALSE;
465 TString cIdSensDr = "J";
466 TString cIdSensAm = "K";
467 Char_t cIdChamber[3];
475 const Int_t kNplan = AliTRDgeometry::Nplan();
476 const Int_t kNcham = AliTRDgeometry::Ncham();
477 const Int_t kNdetsec = kNplan * kNcham;
479 const Double_t kBig = 1.0e+12; // Infinitely big
480 const Float_t kWion = 23.53; // Ionization energy
481 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
483 // Minimum energy for the step size adjustment
484 const Float_t kEkinMinStep = 1.0e-5;
485 // energy threshold for production of delta electrons
486 const Float_t kECut = 1.0e4;
487 // Parameters entering the parametrized range for delta electrons
488 const Float_t kRa = 5.37e-4;
489 const Float_t kRb = 0.9815;
490 const Float_t kRc = 3.123e-3;
491 // Gas density -> To be made user adjustable !
492 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
493 const Float_t kRho = 0.004945 ;
495 // Plateau value of the energy-loss for electron in xenon
496 // The averaged value (26/3/99)
497 const Float_t kPlateau = 1.55;
498 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
499 const Float_t kPrim = 19.34;
500 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
501 const Float_t kPoti = 12.1;
503 const Int_t kPdgElectron = 11;
505 // Set the maximum step size to a very large number for all
506 // neutral particles and those outside the driftvolume
507 gMC->SetMaxStep(kBig);
509 // Use only charged tracks
510 if (( gMC->TrackCharge() ) &&
511 (!gMC->IsTrackDisappeared())) {
513 // Inside a sensitive volume?
516 cIdCurrent = gMC->CurrentVolName();
517 if (cIdSensDr == cIdCurrent[1]) {
520 if (cIdSensAm == cIdCurrent[1]) {
523 if (drRegion || amRegion) {
525 // The hit coordinates and charge
526 gMC->TrackPosition(pos);
531 // The sector number (0 - 17), according to standard coordinate system
532 cIdPath = gGeoManager->GetPath();
533 cIdSector[0] = cIdPath[21];
534 cIdSector[1] = cIdPath[22];
535 sec = atoi(cIdSector);
537 // The plane and chamber number
538 cIdChamber[0] = cIdCurrent[2];
539 cIdChamber[1] = cIdCurrent[3];
540 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
541 cha = ((Int_t) idChamber / kNplan);
542 pla = ((Int_t) idChamber % kNplan);
544 // The detector number
545 det = fGeometry->GetDetector(pla,cha,sec);
547 // Special hits only in the drift region
549 (gMC->IsTrackEntering())) {
551 // Create a track reference at the entrance of each
552 // chamber that contains the momentum components of the particle
553 gMC->TrackMomentum(mom);
554 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
556 // Create the hits from TR photons if electron/positron is
557 // entering the drift volume
559 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
564 else if ((amRegion) &&
565 (gMC->IsTrackExiting())) {
567 // Create a track reference at the exit of each
568 // chamber that contains the momentum components of the particle
569 gMC->TrackMomentum(mom);
570 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
574 // Calculate the energy of the delta-electrons
575 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
576 // take into account correlation with the underlying GEANT tracking
578 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
580 // determine the most significant process (last on the processes list)
581 // which caused this hit
582 gMC->StepProcesses(processes);
583 Int_t nofprocesses = processes.GetSize();
589 pid = processes[nofprocesses-1];
592 // Generate Edep according to GEANT parametrisation
593 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
594 eDelta = TMath::Max(eDelta,0.0);
595 Float_t prRange = 0.0;
596 Float_t range = gMC->TrackLength() - fTrackLength0;
597 // merge GEANT tracker information with locally cooked one
598 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
600 if (eDelta >= kECut) {
601 prRange = kRa * eDelta * 0.001
602 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
603 if (prRange >= (3.7 - range)) {
609 if (eDelta < kECut) {
613 prRange = kRa * eDelta * 0.001
614 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
615 if (prRange >= ((AliTRDgeometry::DrThick()
616 + AliTRDgeometry::AmThick()) - range)) {
632 // Generate the electron cluster size
635 qTot = ((Int_t) (eDelta / kWion) + 1);
637 // Create a new dEdx hit
638 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
642 ,gMC->TrackTime()*1.0e06
647 // Calculate the maximum step size for the next tracking step
648 // Produce only one hit if Ekin is below cutoff
649 aMass = gMC->TrackMass();
650 if ((gMC->Etot() - aMass) > kEkinMinStep) {
652 // The energy loss according to Bethe Bloch
653 iPdg = TMath::Abs(gMC->TrackPid());
654 if ((iPdg != kPdgElectron) ||
655 ((iPdg == kPdgElectron) &&
656 (pTot < kPTotMaxEl))) {
657 gMC->TrackMomentum(mom);
659 betaGamma = pTot / aMass;
660 pp = BetheBlochGeant(betaGamma);
661 // Take charge > 1 into account
662 charge = gMC->TrackCharge();
663 if (TMath::Abs(charge) > 1) {
664 pp = pp * charge*charge;
668 // Electrons above 20 Mev/c are at the plateau
669 pp = kPrim * kPlateau;
674 nsteps = gRandom->Poisson(pp);
676 stepSize = 1.0 / nsteps;
677 gMC->SetMaxStep(stepSize);
687 //_____________________________________________________________________________
688 void AliTRDv1::StepManagerErmilova()
691 // Slow simulator. Every charged track produces electron cluster as hits
692 // along its path across the drift volume. The step size is set acording
693 // to Bethe-Bloch. The energy distribution of the delta electrons follows
694 // a spectrum taken from Ermilova et al.
715 Bool_t drRegion = kFALSE;
716 Bool_t amRegion = kFALSE;
723 TString cIdSensDr = "J";
724 TString cIdSensAm = "K";
725 Char_t cIdChamber[3];
731 const Int_t kNplan = AliTRDgeometry::Nplan();
732 const Int_t kNcham = AliTRDgeometry::Ncham();
733 const Int_t kNdetsec = kNplan * kNcham;
735 const Double_t kBig = 1.0e+12; // Infinitely big
736 const Float_t kWion = 23.53; // Ionization energy
737 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
739 // Minimum energy for the step size adjustment
740 const Float_t kEkinMinStep = 1.0e-5;
742 // Plateau value of the energy-loss for electron in xenon
743 // The averaged value (26/3/99)
744 const Float_t kPlateau = 1.55;
745 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
746 const Float_t kPrim = 48.0;
747 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
748 const Float_t kPoti = 12.1;
750 const Int_t kPdgElectron = 11;
752 // Set the maximum step size to a very large number for all
753 // neutral particles and those outside the driftvolume
754 gMC->SetMaxStep(kBig);
756 // Use only charged tracks
757 if (( gMC->TrackCharge() ) &&
758 (!gMC->IsTrackDisappeared())) {
760 // Inside a sensitive volume?
763 cIdCurrent = gMC->CurrentVolName();
764 if (cIdSensDr == cIdCurrent[1]) {
767 if (cIdSensAm == cIdCurrent[1]) {
770 if (drRegion || amRegion) {
772 // The hit coordinates and charge
773 gMC->TrackPosition(pos);
778 // The sector number (0 - 17), according to standard coordinate system
779 cIdPath = gGeoManager->GetPath();
780 cIdSector[0] = cIdPath[21];
781 cIdSector[1] = cIdPath[22];
782 sec = atoi(cIdSector);
784 // The plane and chamber number
785 cIdChamber[0] = cIdCurrent[2];
786 cIdChamber[1] = cIdCurrent[3];
787 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
788 cha = ((Int_t) idChamber / kNplan);
789 pla = ((Int_t) idChamber % kNplan);
791 // The detector number
792 det = fGeometry->GetDetector(pla,cha,sec);
794 // Special hits only in the drift region
796 (gMC->IsTrackEntering())) {
798 // Create a track reference at the entrance of each
799 // chamber that contains the momentum components of the particle
800 gMC->TrackMomentum(mom);
801 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
803 // Create the hits from TR photons if electron/positron is
804 // entering the drift volume
806 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
811 else if ((amRegion) &&
812 (gMC->IsTrackExiting())) {
814 // Create a track reference at the exit of each
815 // chamber that contains the momentum components of the particle
816 gMC->TrackMomentum(mom);
817 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
821 // Calculate the energy of the delta-electrons
822 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
823 eDelta = TMath::Max(eDelta,0.0);
825 // Generate the electron cluster size
828 qTot = ((Int_t) (eDelta / kWion) + 1);
830 // Create a new dEdx hit
832 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
836 ,gMC->TrackTime()*1.0e06
840 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
844 ,gMC->TrackTime()*1.0e06
850 // Calculate the maximum step size for the next tracking step
851 // Produce only one hit if Ekin is below cutoff
852 aMass = gMC->TrackMass();
853 if ((gMC->Etot() - aMass) > kEkinMinStep) {
855 // The energy loss according to Bethe Bloch
856 iPdg = TMath::Abs(gMC->TrackPid());
857 if ((iPdg != kPdgElectron) ||
858 ((iPdg == kPdgElectron) &&
859 (pTot < kPTotMaxEl))) {
860 gMC->TrackMomentum(mom);
862 betaGamma = pTot / aMass;
863 pp = kPrim * BetheBloch(betaGamma);
864 // Take charge > 1 into account
865 charge = gMC->TrackCharge();
866 if (TMath::Abs(charge) > 1) {
867 pp = pp * charge*charge;
871 // Electrons above 20 Mev/c are at the plateau
872 pp = kPrim * kPlateau;
877 gMC->GetRandom()->RndmArray(1,random);
879 while ((random[0] == 1.0) ||
881 stepSize = - TMath::Log(random[0]) / pp;
882 gMC->SetMaxStep(stepSize);
893 //_____________________________________________________________________________
894 void AliTRDv1::StepManagerFixedStep()
897 // Slow simulator. Every charged track produces electron cluster as hits
898 // along its path across the drift volume. The step size is fixed in
899 // this version of the step manager.
903 const Int_t kPdgElectron = 11;
914 Bool_t drRegion = kFALSE;
915 Bool_t amRegion = kFALSE;
922 TString cIdSensDr = "J";
923 TString cIdSensAm = "K";
924 Char_t cIdChamber[3];
930 const Int_t kNplan = AliTRDgeometry::Nplan();
931 const Int_t kNcham = AliTRDgeometry::Ncham();
932 const Int_t kNdetsec = kNplan * kNcham;
934 const Double_t kBig = 1.0e+12;
936 const Float_t kWion = 23.53; // Ionization energy
937 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
939 // Set the maximum step size to a very large number for all
940 // neutral particles and those outside the driftvolume
941 gMC->SetMaxStep(kBig);
943 // If not charged track or already stopped or disappeared, just return.
944 if ((!gMC->TrackCharge()) ||
945 gMC->IsTrackDisappeared()) {
949 // Inside a sensitive volume?
950 cIdCurrent = gMC->CurrentVolName();
952 if (cIdSensDr == cIdCurrent[1]) {
955 if (cIdSensAm == cIdCurrent[1]) {
964 // The hit coordinates and charge
965 gMC->TrackPosition(pos);
970 // The sector number (0 - 17), according to standard coordinate system
971 cIdPath = gGeoManager->GetPath();
972 cIdSector[0] = cIdPath[21];
973 cIdSector[1] = cIdPath[22];
974 sec = atoi(cIdSector);
976 // The plane and chamber number
977 cIdChamber[0] = cIdCurrent[2];
978 cIdChamber[1] = cIdCurrent[3];
979 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
980 cha = ((Int_t) idChamber / kNplan);
981 pla = ((Int_t) idChamber % kNplan);
983 // The detector number
984 det = fGeometry->GetDetector(pla,cha,sec);
986 // 0: InFlight 1:Entering 2:Exiting
989 // Special hits only in the drift region
991 (gMC->IsTrackEntering())) {
993 // Create a track reference at the entrance of each
994 // chamber that contains the momentum components of the particle
995 gMC->TrackMomentum(mom);
996 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
999 // Create the hits from TR photons if electron/positron is
1000 // entering the drift volume
1002 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
1007 else if ((amRegion) &&
1008 (gMC->IsTrackExiting())) {
1010 // Create a track reference at the exit of each
1011 // chamber that contains the momentum components of the particle
1012 gMC->TrackMomentum(mom);
1013 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
1018 // Calculate the charge according to GEANT Edep
1019 // Create a new dEdx hit
1020 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1021 qTot = (Int_t) (eDep / kWion);
1024 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1028 ,gMC->TrackTime()*1.0e06
1032 // Set Maximum Step Size
1033 // Produce only one hit if Ekin is below cutoff
1034 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1037 gMC->SetMaxStep(fStepSize);
1041 //_____________________________________________________________________________
1042 Double_t AliTRDv1::BetheBloch(Double_t bg)
1045 // Parametrization of the Bethe-Bloch-curve
1046 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1049 // This parameters have been adjusted to averaged values from GEANT
1050 const Double_t kP1 = 7.17960e-02;
1051 const Double_t kP2 = 8.54196;
1052 const Double_t kP3 = 1.38065e-06;
1053 const Double_t kP4 = 5.30972;
1054 const Double_t kP5 = 2.83798;
1056 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1057 const Double_t kBgMin = 0.8;
1058 const Double_t kBBMax = 6.83298;
1061 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
1062 Double_t aa = TMath::Power(yy,kP4);
1063 Double_t bb = TMath::Power((1.0/bg),kP5);
1064 bb = TMath::Log(kP3 + bb);
1065 return ((kP2 - aa - bb) * kP1 / aa);
1073 //_____________________________________________________________________________
1074 Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
1077 // Return dN/dx (number of primary collisions per centimeter)
1078 // for given beta*gamma factor.
1080 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1081 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1082 // This must be used as a set with IntSpecGeant.
1087 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1088 , 1.800000, 2.000000, 2.500000, 3.000000
1089 , 4.000000, 7.000000, 10.000000, 20.000000
1090 , 40.000000, 70.000000, 100.000000, 300.000000
1091 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
1093 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1094 , 22.734999, 21.411915, 19.934095, 19.449375
1095 , 19.344431, 20.185553, 21.027925, 22.912676
1096 , 24.933352, 26.504053, 27.387468, 29.566597
1097 , 30.353779, 30.787134, 31.129285, 31.157350 };
1099 // Betagamma to gamma
1100 Double_t g = TMath::Sqrt(1.0 + bg*bg);
1102 // Find the index just before the point we need.
1103 for (i = 0; i < 18; i++) {
1104 if ((arrG[i] < g) &&
1110 // Simple interpolation.
1111 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1112 * (g - arrG[i]) + arrNC[i];
1118 //_____________________________________________________________________________
1119 Double_t Ermilova(Double_t *x, Double_t *)
1122 // Calculates the delta-ray energy distribution according to Ermilova.
1123 // Logarithmic scale !
1133 const Int_t kNv = 31;
1135 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1136 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1137 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1138 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1139 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1140 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1143 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1144 , 20.9, 20.8, 20.0, 16.0, 11.0
1145 , 8.0, 6.0, 5.2, 4.6, 4.0
1146 , 3.5, 3.0, 1.4, 0.67, 0.44
1147 , 0.3, 0.18, 0.12, 0.08, 0.056
1148 , 0.04, 0.023, 0.015, 0.011, 0.01
1153 // Find the position
1158 dpos = energy - vxe[pos2++];
1167 // Differentiate between the sampling points
1168 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1174 //_____________________________________________________________________________
1175 Double_t IntSpecGeant(Double_t *x, Double_t *)
1178 // Integrated spectrum from Geant3
1181 const Int_t npts = 83;
1182 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1183 , 2.672067, 2.813299, 3.015059, 3.216819
1184 , 3.418579, 3.620338, 3.868209, 3.920198
1185 , 3.978284, 4.063923, 4.186264, 4.308605
1186 , 4.430946, 4.553288, 4.724261, 4.837736
1187 , 4.999842, 5.161949, 5.324056, 5.486163
1188 , 5.679688, 5.752998, 5.857728, 5.962457
1189 , 6.067185, 6.171914, 6.315653, 6.393674
1190 , 6.471694, 6.539689, 6.597658, 6.655627
1191 , 6.710957, 6.763648, 6.816338, 6.876198
1192 , 6.943227, 7.010257, 7.106285, 7.252151
1193 , 7.460531, 7.668911, 7.877290, 8.085670
1194 , 8.302979, 8.353585, 8.413120, 8.483500
1195 , 8.541030, 8.592857, 8.668865, 8.820485
1196 , 9.037086, 9.253686, 9.470286, 9.686887
1197 , 9.930838, 9.994655, 10.085822, 10.176990
1198 , 10.268158, 10.359325, 10.503614, 10.627565
1199 , 10.804637, 10.981709, 11.158781, 11.335854
1200 , 11.593397, 11.781165, 12.049404, 12.317644
1201 , 12.585884, 12.854123, 14.278421, 16.975889
1202 , 20.829416, 24.682943, 28.536469 };
1204 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1205 , 9.1601500, 8.206670, 6.919630, 5.655430
1206 , 4.6221300, 3.777610, 3.019560, 2.591950
1207 , 2.5414600, 2.712920, 3.327460, 4.928240
1208 , 7.6185300, 10.966700, 12.225800, 8.094750
1209 , 3.3586900, 1.553650, 1.209600, 1.263840
1210 , 1.3241100, 1.312140, 1.255130, 1.165770
1211 , 1.0594500, 0.945450, 0.813231, 0.699837
1212 , 0.6235580, 2.260990, 2.968350, 2.240320
1213 , 1.7988300, 1.553300, 1.432070, 1.535520
1214 , 1.4429900, 1.247990, 1.050750, 0.829549
1215 , 0.5900280, 0.395897, 0.268741, 0.185320
1216 , 0.1292120, 0.103545, 0.0949525, 0.101535
1217 , 0.1276380, 0.134216, 0.123816, 0.104557
1218 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1219 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1220 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1221 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1222 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1223 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1224 , 3.63304e-06, 0.0000000, 0.0000000 };
1227 Double_t energy = x[0];
1229 if (energy >= arre[npts-1]) {
1233 for (i = 0; i < npts; i++) {
1234 if (energy < arre[i]) {
1240 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");