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++) {
160 if (fGeometry->GetSMstatus(isect) == 0) continue;
162 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
163 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
165 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
173 volPath += Form("%02d",idet);
177 symName += Form("%02d",isect);
183 TGeoPNEntry *alignableEntry =
184 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
186 // Add the tracking to local matrix following the TPC example
187 if (alignableEntry) {
188 const char *path = alignableEntry->GetTitle();
189 if (!gGeoManager->cd(path)) {
190 AliFatal(Form("Volume path %s not valid!",path));
192 TGeoHMatrix *globMatrix = gGeoManager->GetCurrentMatrix();
193 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
194 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
195 t2lMatrix->RotateZ(sectorAngle);
196 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
197 alignableEntry->SetMatrix(t2lMatrix);
200 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
209 //_____________________________________________________________________________
210 void AliTRDv1::CreateGeometry()
213 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
214 // This version covers the full azimuth.
217 // Check that FRAME is there otherwise we have no place where to put the TRD
218 AliModule* frame = gAlice->GetModule("FRAME");
220 AliError("TRD needs FRAME to be present\n");
224 // Define the chambers
225 AliTRD::CreateGeometry();
229 //_____________________________________________________________________________
230 void AliTRDv1::CreateMaterials()
233 // Create materials for the Transition Radiation Detector version 1
236 AliTRD::CreateMaterials();
240 //_____________________________________________________________________________
241 void AliTRDv1::CreateTRhit(Int_t det)
244 // Creates an electron cluster from a TR photon.
245 // The photon is assumed to be created a the end of the radiator. The
246 // distance after which it deposits its energy takes into account the
247 // absorbtion of the entrance window and of the gas mixture in drift
252 const Float_t kWion = 23.53;
254 // Maximum number of TR photons per track
255 const Int_t kNTR = 50;
264 gMC->TrackMomentum(mom);
265 Float_t pTot = mom.Rho();
266 fTR->CreatePhotons(11,pTot,nTR,eTR);
268 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
271 // Loop through the TR photons
272 for (Int_t iTR = 0; iTR < nTR; iTR++) {
274 Float_t energyMeV = eTR[iTR] * 0.001;
275 Float_t energyeV = eTR[iTR] * 1000.0;
276 Float_t absLength = 0.0;
279 // Take the absorbtion in the entrance window into account
280 Double_t muMy = fTR->GetMuMy(energyMeV);
281 sigma = muMy * fFoilDensity;
283 absLength = gRandom->Exp(1.0/sigma);
284 if (absLength < AliTRDgeometry::MyThick()) {
292 // The absorbtion cross sections in the drift gas
293 // Gas-mixture (Xe/CO2)
294 Double_t muXe = fTR->GetMuXe(energyMeV);
295 Double_t muCO = fTR->GetMuCO(energyMeV);
296 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
298 // The distance after which the energy of the TR photon
301 absLength = gRandom->Exp(1.0/sigma);
302 if (absLength > (AliTRDgeometry::DrThick()
303 + AliTRDgeometry::AmThick())) {
311 // The position of the absorbtion
313 gMC->TrackPosition(pos);
314 posHit[0] = pos[0] + mom[0] / pTot * absLength;
315 posHit[1] = pos[1] + mom[1] / pTot * absLength;
316 posHit[2] = pos[2] + mom[2] / pTot * absLength;
319 Int_t q = ((Int_t) (energyeV / kWion));
321 // Add the hit to the array. TR photon hits are marked
322 // by negative charge
323 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
327 ,gMC->TrackTime()*1.0e06
334 //_____________________________________________________________________________
335 void AliTRDv1::Init()
338 // Initialise Transition Radiation Detector after geometry has been built.
343 AliDebug(1,"Slow simulator\n");
345 // Switch on TR simulation as default
347 AliInfo("TR simulation off");
350 fTR = new AliTRDsimTR();
353 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
354 const Float_t kPoti = 12.1;
355 // Maximum energy (50 keV);
356 const Float_t kEend = 50000.0;
357 // Ermilova distribution for the delta-ray spectrum
358 Float_t poti = TMath::Log(kPoti);
359 Float_t eEnd = TMath::Log(kEend);
361 // Ermilova distribution for the delta-ray spectrum
362 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
364 // Geant3 distribution for the delta-ray spectrum
365 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
367 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
371 //_____________________________________________________________________________
372 void AliTRDv1::StepManager()
375 // Slow simulator. Every charged track produces electron cluster as hits
376 // along its path across the drift volume.
379 switch (fTypeOfStepManager) {
381 StepManagerErmilova();
387 StepManagerFixedStep();
390 AliWarning("Not a valid Step Manager.");
395 //_____________________________________________________________________________
396 void AliTRDv1::SelectStepManager(Int_t t)
399 // Selects a step manager type:
402 // 2 - Fixed step size
405 fTypeOfStepManager = t;
406 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
410 //_____________________________________________________________________________
411 void AliTRDv1::StepManagerGeant()
414 // Slow simulator. Every charged track produces electron cluster as hits
415 // along its path across the drift volume. The step size is set acording
416 // to Bethe-Bloch. The energy distribution of the delta electrons follows
417 // a spectrum taken from Geant3.
419 // Version by A. Bercuci
437 Double_t stepSize = 0;
439 Bool_t drRegion = kFALSE;
440 Bool_t amRegion = kFALSE;
447 TString cIdSensDr = "J";
448 TString cIdSensAm = "K";
449 Char_t cIdChamber[3];
457 const Int_t kNplan = AliTRDgeometry::Nplan();
458 const Int_t kNcham = AliTRDgeometry::Ncham();
459 const Int_t kNdetsec = kNplan * kNcham;
461 const Double_t kBig = 1.0e+12; // Infinitely big
462 const Float_t kWion = 23.53; // Ionization energy
463 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
465 // Minimum energy for the step size adjustment
466 const Float_t kEkinMinStep = 1.0e-5;
467 // energy threshold for production of delta electrons
468 const Float_t kECut = 1.0e4;
469 // Parameters entering the parametrized range for delta electrons
470 const Float_t kRa = 5.37e-4;
471 const Float_t kRb = 0.9815;
472 const Float_t kRc = 3.123e-3;
473 // Gas density -> To be made user adjustable !
474 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
475 const Float_t kRho = 0.004945 ;
477 // Plateau value of the energy-loss for electron in xenon
478 // The averaged value (26/3/99)
479 const Float_t kPlateau = 1.55;
480 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
481 const Float_t kPrim = 19.34;
482 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
483 const Float_t kPoti = 12.1;
485 const Int_t kPdgElectron = 11;
487 // Set the maximum step size to a very large number for all
488 // neutral particles and those outside the driftvolume
489 gMC->SetMaxStep(kBig);
491 // Use only charged tracks
492 if (( gMC->TrackCharge() ) &&
493 (!gMC->IsTrackDisappeared())) {
495 // Inside a sensitive volume?
498 cIdCurrent = gMC->CurrentVolName();
499 if (cIdSensDr == cIdCurrent[1]) {
502 if (cIdSensAm == cIdCurrent[1]) {
505 if (drRegion || amRegion) {
507 // The hit coordinates and charge
508 gMC->TrackPosition(pos);
513 // The sector number (0 - 17), according to standard coordinate system
514 cIdPath = gGeoManager->GetPath();
515 cIdSector[0] = cIdPath[21];
516 cIdSector[1] = cIdPath[22];
517 sec = atoi(cIdSector);
519 // The plane and chamber number
520 cIdChamber[0] = cIdCurrent[2];
521 cIdChamber[1] = cIdCurrent[3];
522 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
523 cha = ((Int_t) idChamber / kNplan);
524 pla = ((Int_t) idChamber % kNplan);
526 // The detector number
527 det = fGeometry->GetDetector(pla,cha,sec);
529 // Special hits only in the drift region
531 (gMC->IsTrackEntering())) {
533 // Create a track reference at the entrance of each
534 // chamber that contains the momentum components of the particle
535 gMC->TrackMomentum(mom);
536 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
538 // Create the hits from TR photons if electron/positron is
539 // entering the drift volume
541 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
546 else if ((amRegion) &&
547 (gMC->IsTrackExiting())) {
549 // Create a track reference at the exit of each
550 // chamber that contains the momentum components of the particle
551 gMC->TrackMomentum(mom);
552 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
556 // Calculate the energy of the delta-electrons
557 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
558 // take into account correlation with the underlying GEANT tracking
560 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
562 // determine the most significant process (last on the processes list)
563 // which caused this hit
564 gMC->StepProcesses(processes);
565 Int_t nofprocesses = processes.GetSize();
571 pid = processes[nofprocesses-1];
574 // Generate Edep according to GEANT parametrisation
575 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
576 eDelta = TMath::Max(eDelta,0.0);
577 Float_t prRange = 0.0;
578 Float_t range = gMC->TrackLength() - fTrackLength0;
579 // merge GEANT tracker information with locally cooked one
580 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
582 if (eDelta >= kECut) {
583 prRange = kRa * eDelta * 0.001
584 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
585 if (prRange >= (3.7 - range)) {
591 if (eDelta < kECut) {
595 prRange = kRa * eDelta * 0.001
596 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
597 if (prRange >= ((AliTRDgeometry::DrThick()
598 + AliTRDgeometry::AmThick()) - range)) {
614 // Generate the electron cluster size
617 qTot = ((Int_t) (eDelta / kWion) + 1);
619 // Create a new dEdx hit
620 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
624 ,gMC->TrackTime()*1.0e06
629 // Calculate the maximum step size for the next tracking step
630 // Produce only one hit if Ekin is below cutoff
631 aMass = gMC->TrackMass();
632 if ((gMC->Etot() - aMass) > kEkinMinStep) {
634 // The energy loss according to Bethe Bloch
635 iPdg = TMath::Abs(gMC->TrackPid());
636 if ((iPdg != kPdgElectron) ||
637 ((iPdg == kPdgElectron) &&
638 (pTot < kPTotMaxEl))) {
639 gMC->TrackMomentum(mom);
641 betaGamma = pTot / aMass;
642 pp = BetheBlochGeant(betaGamma);
643 // Take charge > 1 into account
644 charge = gMC->TrackCharge();
645 if (TMath::Abs(charge) > 1) {
646 pp = pp * charge*charge;
650 // Electrons above 20 Mev/c are at the plateau
651 pp = kPrim * kPlateau;
656 nsteps = gRandom->Poisson(pp);
658 stepSize = 1.0 / nsteps;
659 gMC->SetMaxStep(stepSize);
669 //_____________________________________________________________________________
670 void AliTRDv1::StepManagerErmilova()
673 // Slow simulator. Every charged track produces electron cluster as hits
674 // along its path across the drift volume. The step size is set acording
675 // to Bethe-Bloch. The energy distribution of the delta electrons follows
676 // a spectrum taken from Ermilova et al.
697 Bool_t drRegion = kFALSE;
698 Bool_t amRegion = kFALSE;
705 TString cIdSensDr = "J";
706 TString cIdSensAm = "K";
707 Char_t cIdChamber[3];
713 const Int_t kNplan = AliTRDgeometry::Nplan();
714 const Int_t kNcham = AliTRDgeometry::Ncham();
715 const Int_t kNdetsec = kNplan * kNcham;
717 const Double_t kBig = 1.0e+12; // Infinitely big
718 const Float_t kWion = 23.53; // Ionization energy
719 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
721 // Minimum energy for the step size adjustment
722 const Float_t kEkinMinStep = 1.0e-5;
724 // Plateau value of the energy-loss for electron in xenon
725 // The averaged value (26/3/99)
726 const Float_t kPlateau = 1.55;
727 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
728 const Float_t kPrim = 48.0;
729 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
730 const Float_t kPoti = 12.1;
732 const Int_t kPdgElectron = 11;
734 // Set the maximum step size to a very large number for all
735 // neutral particles and those outside the driftvolume
736 gMC->SetMaxStep(kBig);
738 // Use only charged tracks
739 if (( gMC->TrackCharge() ) &&
740 (!gMC->IsTrackDisappeared())) {
742 // Inside a sensitive volume?
745 cIdCurrent = gMC->CurrentVolName();
746 if (cIdSensDr == cIdCurrent[1]) {
749 if (cIdSensAm == cIdCurrent[1]) {
752 if (drRegion || amRegion) {
754 // The hit coordinates and charge
755 gMC->TrackPosition(pos);
760 // The sector number (0 - 17), according to standard coordinate system
761 cIdPath = gGeoManager->GetPath();
762 cIdSector[0] = cIdPath[21];
763 cIdSector[1] = cIdPath[22];
764 sec = atoi(cIdSector);
766 // The plane and chamber number
767 cIdChamber[0] = cIdCurrent[2];
768 cIdChamber[1] = cIdCurrent[3];
769 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
770 cha = ((Int_t) idChamber / kNplan);
771 pla = ((Int_t) idChamber % kNplan);
773 // The detector number
774 det = fGeometry->GetDetector(pla,cha,sec);
776 // Special hits only in the drift region
778 (gMC->IsTrackEntering())) {
780 // Create a track reference at the entrance of each
781 // chamber that contains the momentum components of the particle
782 gMC->TrackMomentum(mom);
783 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
785 // Create the hits from TR photons if electron/positron is
786 // entering the drift volume
788 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
793 else if ((amRegion) &&
794 (gMC->IsTrackExiting())) {
796 // Create a track reference at the exit of each
797 // chamber that contains the momentum components of the particle
798 gMC->TrackMomentum(mom);
799 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
803 // Calculate the energy of the delta-electrons
804 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
805 eDelta = TMath::Max(eDelta,0.0);
807 // Generate the electron cluster size
810 qTot = ((Int_t) (eDelta / kWion) + 1);
812 // Create a new dEdx hit
814 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
818 ,gMC->TrackTime()*1.0e06
822 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
826 ,gMC->TrackTime()*1.0e06
832 // Calculate the maximum step size for the next tracking step
833 // Produce only one hit if Ekin is below cutoff
834 aMass = gMC->TrackMass();
835 if ((gMC->Etot() - aMass) > kEkinMinStep) {
837 // The energy loss according to Bethe Bloch
838 iPdg = TMath::Abs(gMC->TrackPid());
839 if ((iPdg != kPdgElectron) ||
840 ((iPdg == kPdgElectron) &&
841 (pTot < kPTotMaxEl))) {
842 gMC->TrackMomentum(mom);
844 betaGamma = pTot / aMass;
845 pp = kPrim * BetheBloch(betaGamma);
846 // Take charge > 1 into account
847 charge = gMC->TrackCharge();
848 if (TMath::Abs(charge) > 1) {
849 pp = pp * charge*charge;
853 // Electrons above 20 Mev/c are at the plateau
854 pp = kPrim * kPlateau;
859 gMC->GetRandom()->RndmArray(1,random);
861 while ((random[0] == 1.0) ||
863 stepSize = - TMath::Log(random[0]) / pp;
864 gMC->SetMaxStep(stepSize);
875 //_____________________________________________________________________________
876 void AliTRDv1::StepManagerFixedStep()
879 // Slow simulator. Every charged track produces electron cluster as hits
880 // along its path across the drift volume. The step size is fixed in
881 // this version of the step manager.
885 const Int_t kPdgElectron = 11;
896 Bool_t drRegion = kFALSE;
897 Bool_t amRegion = kFALSE;
904 TString cIdSensDr = "J";
905 TString cIdSensAm = "K";
906 Char_t cIdChamber[3];
912 const Int_t kNplan = AliTRDgeometry::Nplan();
913 const Int_t kNcham = AliTRDgeometry::Ncham();
914 const Int_t kNdetsec = kNplan * kNcham;
916 const Double_t kBig = 1.0e+12;
918 const Float_t kWion = 23.53; // Ionization energy
919 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
921 // Set the maximum step size to a very large number for all
922 // neutral particles and those outside the driftvolume
923 gMC->SetMaxStep(kBig);
925 // If not charged track or already stopped or disappeared, just return.
926 if ((!gMC->TrackCharge()) ||
927 gMC->IsTrackDisappeared()) {
931 // Inside a sensitive volume?
932 cIdCurrent = gMC->CurrentVolName();
934 if (cIdSensDr == cIdCurrent[1]) {
937 if (cIdSensAm == cIdCurrent[1]) {
946 // The hit coordinates and charge
947 gMC->TrackPosition(pos);
952 // The sector number (0 - 17), according to standard coordinate system
953 cIdPath = gGeoManager->GetPath();
954 cIdSector[0] = cIdPath[21];
955 cIdSector[1] = cIdPath[22];
956 sec = atoi(cIdSector);
958 // The plane and chamber number
959 cIdChamber[0] = cIdCurrent[2];
960 cIdChamber[1] = cIdCurrent[3];
961 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
962 cha = ((Int_t) idChamber / kNplan);
963 pla = ((Int_t) idChamber % kNplan);
965 // The detector number
966 det = fGeometry->GetDetector(pla,cha,sec);
968 // 0: InFlight 1:Entering 2:Exiting
971 // Special hits only in the drift region
973 (gMC->IsTrackEntering())) {
975 // Create a track reference at the entrance of each
976 // chamber that contains the momentum components of the particle
977 gMC->TrackMomentum(mom);
978 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
981 // Create the hits from TR photons if electron/positron is
982 // entering the drift volume
984 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
989 else if ((amRegion) &&
990 (gMC->IsTrackExiting())) {
992 // Create a track reference at the exit of each
993 // chamber that contains the momentum components of the particle
994 gMC->TrackMomentum(mom);
995 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
1000 // Calculate the charge according to GEANT Edep
1001 // Create a new dEdx hit
1002 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1003 qTot = (Int_t) (eDep / kWion);
1006 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1010 ,gMC->TrackTime()*1.0e06
1014 // Set Maximum Step Size
1015 // Produce only one hit if Ekin is below cutoff
1016 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1019 gMC->SetMaxStep(fStepSize);
1023 //_____________________________________________________________________________
1024 Double_t AliTRDv1::BetheBloch(Double_t bg)
1027 // Parametrization of the Bethe-Bloch-curve
1028 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1031 // This parameters have been adjusted to averaged values from GEANT
1032 const Double_t kP1 = 7.17960e-02;
1033 const Double_t kP2 = 8.54196;
1034 const Double_t kP3 = 1.38065e-06;
1035 const Double_t kP4 = 5.30972;
1036 const Double_t kP5 = 2.83798;
1038 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1039 const Double_t kBgMin = 0.8;
1040 const Double_t kBBMax = 6.83298;
1043 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
1044 Double_t aa = TMath::Power(yy,kP4);
1045 Double_t bb = TMath::Power((1.0/bg),kP5);
1046 bb = TMath::Log(kP3 + bb);
1047 return ((kP2 - aa - bb) * kP1 / aa);
1055 //_____________________________________________________________________________
1056 Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
1059 // Return dN/dx (number of primary collisions per centimeter)
1060 // for given beta*gamma factor.
1062 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1063 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1064 // This must be used as a set with IntSpecGeant.
1069 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1070 , 1.800000, 2.000000, 2.500000, 3.000000
1071 , 4.000000, 7.000000, 10.000000, 20.000000
1072 , 40.000000, 70.000000, 100.000000, 300.000000
1073 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
1075 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1076 , 22.734999, 21.411915, 19.934095, 19.449375
1077 , 19.344431, 20.185553, 21.027925, 22.912676
1078 , 24.933352, 26.504053, 27.387468, 29.566597
1079 , 30.353779, 30.787134, 31.129285, 31.157350 };
1081 // Betagamma to gamma
1082 Double_t g = TMath::Sqrt(1.0 + bg*bg);
1084 // Find the index just before the point we need.
1085 for (i = 0; i < 18; i++) {
1086 if ((arrG[i] < g) &&
1092 // Simple interpolation.
1093 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1094 * (g - arrG[i]) + arrNC[i];
1100 //_____________________________________________________________________________
1101 Double_t Ermilova(Double_t *x, Double_t *)
1104 // Calculates the delta-ray energy distribution according to Ermilova.
1105 // Logarithmic scale !
1115 const Int_t kNv = 31;
1117 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1118 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1119 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1120 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1121 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1122 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1125 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1126 , 20.9, 20.8, 20.0, 16.0, 11.0
1127 , 8.0, 6.0, 5.2, 4.6, 4.0
1128 , 3.5, 3.0, 1.4, 0.67, 0.44
1129 , 0.3, 0.18, 0.12, 0.08, 0.056
1130 , 0.04, 0.023, 0.015, 0.011, 0.01
1135 // Find the position
1140 dpos = energy - vxe[pos2++];
1149 // Differentiate between the sampling points
1150 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1156 //_____________________________________________________________________________
1157 Double_t IntSpecGeant(Double_t *x, Double_t *)
1160 // Integrated spectrum from Geant3
1163 const Int_t npts = 83;
1164 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1165 , 2.672067, 2.813299, 3.015059, 3.216819
1166 , 3.418579, 3.620338, 3.868209, 3.920198
1167 , 3.978284, 4.063923, 4.186264, 4.308605
1168 , 4.430946, 4.553288, 4.724261, 4.837736
1169 , 4.999842, 5.161949, 5.324056, 5.486163
1170 , 5.679688, 5.752998, 5.857728, 5.962457
1171 , 6.067185, 6.171914, 6.315653, 6.393674
1172 , 6.471694, 6.539689, 6.597658, 6.655627
1173 , 6.710957, 6.763648, 6.816338, 6.876198
1174 , 6.943227, 7.010257, 7.106285, 7.252151
1175 , 7.460531, 7.668911, 7.877290, 8.085670
1176 , 8.302979, 8.353585, 8.413120, 8.483500
1177 , 8.541030, 8.592857, 8.668865, 8.820485
1178 , 9.037086, 9.253686, 9.470286, 9.686887
1179 , 9.930838, 9.994655, 10.085822, 10.176990
1180 , 10.268158, 10.359325, 10.503614, 10.627565
1181 , 10.804637, 10.981709, 11.158781, 11.335854
1182 , 11.593397, 11.781165, 12.049404, 12.317644
1183 , 12.585884, 12.854123, 14.278421, 16.975889
1184 , 20.829416, 24.682943, 28.536469 };
1186 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1187 , 9.1601500, 8.206670, 6.919630, 5.655430
1188 , 4.6221300, 3.777610, 3.019560, 2.591950
1189 , 2.5414600, 2.712920, 3.327460, 4.928240
1190 , 7.6185300, 10.966700, 12.225800, 8.094750
1191 , 3.3586900, 1.553650, 1.209600, 1.263840
1192 , 1.3241100, 1.312140, 1.255130, 1.165770
1193 , 1.0594500, 0.945450, 0.813231, 0.699837
1194 , 0.6235580, 2.260990, 2.968350, 2.240320
1195 , 1.7988300, 1.553300, 1.432070, 1.535520
1196 , 1.4429900, 1.247990, 1.050750, 0.829549
1197 , 0.5900280, 0.395897, 0.268741, 0.185320
1198 , 0.1292120, 0.103545, 0.0949525, 0.101535
1199 , 0.1276380, 0.134216, 0.123816, 0.104557
1200 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1201 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1202 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1203 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1204 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1205 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1206 , 3.63304e-06, 0.0000000, 0.0000000 };
1209 Double_t energy = x[0];
1211 if (energy >= arre[npts-1]) {
1215 for (i = 0; i < npts; i++) {
1216 if (energy < arre[i]) {
1222 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");