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 <TGeoMatrix.h>
34 #include <TGeoPhysicalNode.h>
38 #include "AliTrackReference.h"
42 #include "AliTRDgeometry.h"
43 #include "AliTRDhit.h"
44 #include "AliTRDsimTR.h"
49 //_____________________________________________________________________________
54 ,fTypeOfStepManager(0)
62 // Default constructor
67 //_____________________________________________________________________________
68 AliTRDv1::AliTRDv1(const char *name, const char *title)
72 ,fTypeOfStepManager(2)
80 // Standard constructor for Transition Radiation Detector version 1
83 SetBufferSize(128000);
87 //_____________________________________________________________________________
91 // AliTRDv1 destructor
111 //_____________________________________________________________________________
112 void AliTRDv1::AddAlignableVolumes() const
115 // Create entries for alignable volumes associating the symbolic volume
116 // name with the corresponding volume path. Needs to be syncronized with
117 // eventual changes in the geometry.
123 TString vpStr = "ALIC_1/B077_1/BSEGMO";
124 TString vpApp1 = "_1/BTRD";
125 TString vpApp2 = "_1";
126 TString vpApp3a = "/UTR1_1/UTS1_1/UTI1_1/UT";
127 TString vpApp3b = "/UTR2_1/UTS2_1/UTI2_1/UT";
128 TString vpApp3c = "/UTR3_1/UTS3_1/UTI3_1/UT";
130 TString snStr = "TRD/sm";
131 TString snApp1 = "/st";
132 TString snApp2 = "/pl";
136 // The symbolic names are: TRD/sm00
140 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
149 symName += Form("%02d",isect);
151 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
156 // The readout chambers
157 // The symbolic names are: TRD/sm00/st0/pl0
161 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
163 if (fGeometry->GetSMstatus(isect) == 0) continue;
165 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
166 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
168 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
191 volPath += Form("%02d",idet);
195 symName += Form("%02d",isect);
201 TGeoPNEntry *alignableEntry =
202 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
204 // Add the tracking to local matrix following the TPC example
205 if (alignableEntry) {
206 const char *path = alignableEntry->GetTitle();
207 if (!gGeoManager->cd(path)) {
208 AliFatal(Form("Volume path %s not valid!",path));
210 // Is this correct still????
211 TGeoHMatrix *globMatrix = gGeoManager->GetCurrentMatrix();
212 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
213 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
214 t2lMatrix->RotateZ(sectorAngle);
215 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
216 alignableEntry->SetMatrix(t2lMatrix);
219 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
228 //_____________________________________________________________________________
229 void AliTRDv1::CreateGeometry()
232 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
233 // This version covers the full azimuth.
236 // Check that FRAME is there otherwise we have no place where to put the TRD
237 AliModule* frame = gAlice->GetModule("FRAME");
239 AliError("TRD needs FRAME to be present\n");
243 // Define the chambers
244 AliTRD::CreateGeometry();
248 //_____________________________________________________________________________
249 void AliTRDv1::CreateMaterials()
252 // Create materials for the Transition Radiation Detector version 1
255 AliTRD::CreateMaterials();
259 //_____________________________________________________________________________
260 void AliTRDv1::CreateTRhit(Int_t det)
263 // Creates an electron cluster from a TR photon.
264 // The photon is assumed to be created a the end of the radiator. The
265 // distance after which it deposits its energy takes into account the
266 // absorbtion of the entrance window and of the gas mixture in drift
271 const Float_t kWion = 23.53;
273 // Maximum number of TR photons per track
274 const Int_t kNTR = 50;
283 gMC->TrackMomentum(mom);
284 Float_t pTot = mom.Rho();
285 fTR->CreatePhotons(11,pTot,nTR,eTR);
287 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
290 // Loop through the TR photons
291 for (Int_t iTR = 0; iTR < nTR; iTR++) {
293 Float_t energyMeV = eTR[iTR] * 0.001;
294 Float_t energyeV = eTR[iTR] * 1000.0;
295 Float_t absLength = 0.0;
298 // Take the absorbtion in the entrance window into account
299 Double_t muMy = fTR->GetMuMy(energyMeV);
300 sigma = muMy * fFoilDensity;
302 absLength = gRandom->Exp(1.0/sigma);
303 if (absLength < AliTRDgeometry::MyThick()) {
311 // The absorbtion cross sections in the drift gas
312 // Gas-mixture (Xe/CO2)
313 Double_t muXe = fTR->GetMuXe(energyMeV);
314 Double_t muCO = fTR->GetMuCO(energyMeV);
315 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
317 // The distance after which the energy of the TR photon
320 absLength = gRandom->Exp(1.0/sigma);
321 if (absLength > (AliTRDgeometry::DrThick()
322 + AliTRDgeometry::AmThick())) {
330 // The position of the absorbtion
332 gMC->TrackPosition(pos);
333 posHit[0] = pos[0] + mom[0] / pTot * absLength;
334 posHit[1] = pos[1] + mom[1] / pTot * absLength;
335 posHit[2] = pos[2] + mom[2] / pTot * absLength;
338 Int_t q = ((Int_t) (energyeV / kWion));
340 // Add the hit to the array. TR photon hits are marked
341 // by negative charge
342 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
346 ,gMC->TrackTime()*1.0e06
353 //_____________________________________________________________________________
354 void AliTRDv1::Init()
357 // Initialise Transition Radiation Detector after geometry has been built.
362 AliDebug(1,"Slow simulator\n");
364 // Switch on TR simulation as default
366 AliInfo("TR simulation off");
369 fTR = new AliTRDsimTR();
372 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
373 const Float_t kPoti = 12.1;
374 // Maximum energy (50 keV);
375 const Float_t kEend = 50000.0;
376 // Ermilova distribution for the delta-ray spectrum
377 Float_t poti = TMath::Log(kPoti);
378 Float_t eEnd = TMath::Log(kEend);
380 // Ermilova distribution for the delta-ray spectrum
381 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
383 // Geant3 distribution for the delta-ray spectrum
384 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
386 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
390 //_____________________________________________________________________________
391 void AliTRDv1::StepManager()
394 // Slow simulator. Every charged track produces electron cluster as hits
395 // along its path across the drift volume.
398 switch (fTypeOfStepManager) {
400 StepManagerErmilova();
406 StepManagerFixedStep();
409 AliWarning("Not a valid Step Manager.");
414 //_____________________________________________________________________________
415 void AliTRDv1::SelectStepManager(Int_t t)
418 // Selects a step manager type:
421 // 2 - Fixed step size
424 fTypeOfStepManager = t;
425 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
429 //_____________________________________________________________________________
430 void AliTRDv1::StepManagerGeant()
433 // Slow simulator. Every charged track produces electron cluster as hits
434 // along its path across the drift volume. The step size is set acording
435 // to Bethe-Bloch. The energy distribution of the delta electrons follows
436 // a spectrum taken from Geant3.
438 // Version by A. Bercuci
456 Double_t stepSize = 0;
458 Bool_t drRegion = kFALSE;
459 Bool_t amRegion = kFALSE;
466 TString cIdSensDr = "J";
467 TString cIdSensAm = "K";
468 Char_t cIdChamber[3];
476 const Int_t kNplan = AliTRDgeometry::Nplan();
477 const Int_t kNcham = AliTRDgeometry::Ncham();
478 const Int_t kNdetsec = kNplan * kNcham;
480 const Double_t kBig = 1.0e+12; // Infinitely big
481 const Float_t kWion = 23.53; // Ionization energy
482 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
484 // Minimum energy for the step size adjustment
485 const Float_t kEkinMinStep = 1.0e-5;
486 // energy threshold for production of delta electrons
487 const Float_t kECut = 1.0e4;
488 // Parameters entering the parametrized range for delta electrons
489 const Float_t kRa = 5.37e-4;
490 const Float_t kRb = 0.9815;
491 const Float_t kRc = 3.123e-3;
492 // Gas density -> To be made user adjustable !
493 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
494 const Float_t kRho = 0.004945 ;
496 // Plateau value of the energy-loss for electron in xenon
497 // The averaged value (26/3/99)
498 const Float_t kPlateau = 1.55;
499 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
500 const Float_t kPrim = 19.34;
501 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
502 const Float_t kPoti = 12.1;
504 const Int_t kPdgElectron = 11;
506 // Set the maximum step size to a very large number for all
507 // neutral particles and those outside the driftvolume
508 gMC->SetMaxStep(kBig);
510 // Use only charged tracks
511 if (( gMC->TrackCharge() ) &&
512 (!gMC->IsTrackDisappeared())) {
514 // Inside a sensitive volume?
517 cIdCurrent = gMC->CurrentVolName();
518 if (cIdSensDr == cIdCurrent[1]) {
521 if (cIdSensAm == cIdCurrent[1]) {
524 if (drRegion || amRegion) {
526 // The hit coordinates and charge
527 gMC->TrackPosition(pos);
532 // The sector number (0 - 17), according to standard coordinate system
533 cIdPath = gGeoManager->GetPath();
534 cIdSector[0] = cIdPath[21];
535 cIdSector[1] = cIdPath[22];
536 sec = atoi(cIdSector);
538 // The plane and chamber number
539 cIdChamber[0] = cIdCurrent[2];
540 cIdChamber[1] = cIdCurrent[3];
541 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
542 cha = ((Int_t) idChamber / kNplan);
543 pla = ((Int_t) idChamber % kNplan);
545 // The detector number
546 det = fGeometry->GetDetector(pla,cha,sec);
548 // Special hits only in the drift region
550 (gMC->IsTrackEntering())) {
552 // Create a track reference at the entrance of each
553 // chamber that contains the momentum components of the particle
554 gMC->TrackMomentum(mom);
555 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
557 // Create the hits from TR photons if electron/positron is
558 // entering the drift volume
560 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
565 else if ((amRegion) &&
566 (gMC->IsTrackExiting())) {
568 // Create a track reference at the exit of each
569 // chamber that contains the momentum components of the particle
570 gMC->TrackMomentum(mom);
571 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
575 // Calculate the energy of the delta-electrons
576 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
577 // take into account correlation with the underlying GEANT tracking
579 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
581 // determine the most significant process (last on the processes list)
582 // which caused this hit
583 gMC->StepProcesses(processes);
584 Int_t nofprocesses = processes.GetSize();
590 pid = processes[nofprocesses-1];
593 // Generate Edep according to GEANT parametrisation
594 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
595 eDelta = TMath::Max(eDelta,0.0);
596 Float_t prRange = 0.0;
597 Float_t range = gMC->TrackLength() - fTrackLength0;
598 // merge GEANT tracker information with locally cooked one
599 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
601 if (eDelta >= kECut) {
602 prRange = kRa * eDelta * 0.001
603 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
604 if (prRange >= (3.7 - range)) {
610 if (eDelta < kECut) {
614 prRange = kRa * eDelta * 0.001
615 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
616 if (prRange >= ((AliTRDgeometry::DrThick()
617 + AliTRDgeometry::AmThick()) - range)) {
633 // Generate the electron cluster size
636 qTot = ((Int_t) (eDelta / kWion) + 1);
638 // Create a new dEdx hit
639 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
643 ,gMC->TrackTime()*1.0e06
648 // Calculate the maximum step size for the next tracking step
649 // Produce only one hit if Ekin is below cutoff
650 aMass = gMC->TrackMass();
651 if ((gMC->Etot() - aMass) > kEkinMinStep) {
653 // The energy loss according to Bethe Bloch
654 iPdg = TMath::Abs(gMC->TrackPid());
655 if ((iPdg != kPdgElectron) ||
656 ((iPdg == kPdgElectron) &&
657 (pTot < kPTotMaxEl))) {
658 gMC->TrackMomentum(mom);
660 betaGamma = pTot / aMass;
661 pp = BetheBlochGeant(betaGamma);
662 // Take charge > 1 into account
663 charge = gMC->TrackCharge();
664 if (TMath::Abs(charge) > 1) {
665 pp = pp * charge*charge;
669 // Electrons above 20 Mev/c are at the plateau
670 pp = kPrim * kPlateau;
675 nsteps = gRandom->Poisson(pp);
677 stepSize = 1.0 / nsteps;
678 gMC->SetMaxStep(stepSize);
688 //_____________________________________________________________________________
689 void AliTRDv1::StepManagerErmilova()
692 // Slow simulator. Every charged track produces electron cluster as hits
693 // along its path across the drift volume. The step size is set acording
694 // to Bethe-Bloch. The energy distribution of the delta electrons follows
695 // a spectrum taken from Ermilova et al.
716 Bool_t drRegion = kFALSE;
717 Bool_t amRegion = kFALSE;
724 TString cIdSensDr = "J";
725 TString cIdSensAm = "K";
726 Char_t cIdChamber[3];
732 const Int_t kNplan = AliTRDgeometry::Nplan();
733 const Int_t kNcham = AliTRDgeometry::Ncham();
734 const Int_t kNdetsec = kNplan * kNcham;
736 const Double_t kBig = 1.0e+12; // Infinitely big
737 const Float_t kWion = 23.53; // Ionization energy
738 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
740 // Minimum energy for the step size adjustment
741 const Float_t kEkinMinStep = 1.0e-5;
743 // Plateau value of the energy-loss for electron in xenon
744 // The averaged value (26/3/99)
745 const Float_t kPlateau = 1.55;
746 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
747 const Float_t kPrim = 48.0;
748 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
749 const Float_t kPoti = 12.1;
751 const Int_t kPdgElectron = 11;
753 // Set the maximum step size to a very large number for all
754 // neutral particles and those outside the driftvolume
755 gMC->SetMaxStep(kBig);
757 // Use only charged tracks
758 if (( gMC->TrackCharge() ) &&
759 (!gMC->IsTrackDisappeared())) {
761 // Inside a sensitive volume?
764 cIdCurrent = gMC->CurrentVolName();
765 if (cIdSensDr == cIdCurrent[1]) {
768 if (cIdSensAm == cIdCurrent[1]) {
771 if (drRegion || amRegion) {
773 // The hit coordinates and charge
774 gMC->TrackPosition(pos);
779 // The sector number (0 - 17), according to standard coordinate system
780 cIdPath = gGeoManager->GetPath();
781 cIdSector[0] = cIdPath[21];
782 cIdSector[1] = cIdPath[22];
783 sec = atoi(cIdSector);
785 // The plane and chamber number
786 cIdChamber[0] = cIdCurrent[2];
787 cIdChamber[1] = cIdCurrent[3];
788 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
789 cha = ((Int_t) idChamber / kNplan);
790 pla = ((Int_t) idChamber % kNplan);
792 // The detector number
793 det = fGeometry->GetDetector(pla,cha,sec);
795 // Special hits only in the drift region
797 (gMC->IsTrackEntering())) {
799 // Create a track reference at the entrance of each
800 // chamber that contains the momentum components of the particle
801 gMC->TrackMomentum(mom);
802 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
804 // Create the hits from TR photons if electron/positron is
805 // entering the drift volume
807 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
812 else if ((amRegion) &&
813 (gMC->IsTrackExiting())) {
815 // Create a track reference at the exit of each
816 // chamber that contains the momentum components of the particle
817 gMC->TrackMomentum(mom);
818 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
822 // Calculate the energy of the delta-electrons
823 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
824 eDelta = TMath::Max(eDelta,0.0);
826 // Generate the electron cluster size
829 qTot = ((Int_t) (eDelta / kWion) + 1);
831 // Create a new dEdx hit
833 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
837 ,gMC->TrackTime()*1.0e06
841 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
845 ,gMC->TrackTime()*1.0e06
851 // Calculate the maximum step size for the next tracking step
852 // Produce only one hit if Ekin is below cutoff
853 aMass = gMC->TrackMass();
854 if ((gMC->Etot() - aMass) > kEkinMinStep) {
856 // The energy loss according to Bethe Bloch
857 iPdg = TMath::Abs(gMC->TrackPid());
858 if ((iPdg != kPdgElectron) ||
859 ((iPdg == kPdgElectron) &&
860 (pTot < kPTotMaxEl))) {
861 gMC->TrackMomentum(mom);
863 betaGamma = pTot / aMass;
864 pp = kPrim * BetheBloch(betaGamma);
865 // Take charge > 1 into account
866 charge = gMC->TrackCharge();
867 if (TMath::Abs(charge) > 1) {
868 pp = pp * charge*charge;
872 // Electrons above 20 Mev/c are at the plateau
873 pp = kPrim * kPlateau;
878 gMC->GetRandom()->RndmArray(1,random);
880 while ((random[0] == 1.0) ||
882 stepSize = - TMath::Log(random[0]) / pp;
883 gMC->SetMaxStep(stepSize);
894 //_____________________________________________________________________________
895 void AliTRDv1::StepManagerFixedStep()
898 // Slow simulator. Every charged track produces electron cluster as hits
899 // along its path across the drift volume. The step size is fixed in
900 // this version of the step manager.
904 const Int_t kPdgElectron = 11;
915 Bool_t drRegion = kFALSE;
916 Bool_t amRegion = kFALSE;
923 TString cIdSensDr = "J";
924 TString cIdSensAm = "K";
925 Char_t cIdChamber[3];
931 const Int_t kNplan = AliTRDgeometry::Nplan();
932 const Int_t kNcham = AliTRDgeometry::Ncham();
933 const Int_t kNdetsec = kNplan * kNcham;
935 const Double_t kBig = 1.0e+12;
937 const Float_t kWion = 23.53; // Ionization energy
938 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
940 // Set the maximum step size to a very large number for all
941 // neutral particles and those outside the driftvolume
942 gMC->SetMaxStep(kBig);
944 // If not charged track or already stopped or disappeared, just return.
945 if ((!gMC->TrackCharge()) ||
946 gMC->IsTrackDisappeared()) {
950 // Inside a sensitive volume?
951 cIdCurrent = gMC->CurrentVolName();
953 if (cIdSensDr == cIdCurrent[1]) {
956 if (cIdSensAm == cIdCurrent[1]) {
965 // The hit coordinates and charge
966 gMC->TrackPosition(pos);
971 // The sector number (0 - 17), according to standard coordinate system
972 cIdPath = gGeoManager->GetPath();
973 cIdSector[0] = cIdPath[21];
974 cIdSector[1] = cIdPath[22];
975 sec = atoi(cIdSector);
977 // The plane and chamber number
978 cIdChamber[0] = cIdCurrent[2];
979 cIdChamber[1] = cIdCurrent[3];
980 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
981 cha = ((Int_t) idChamber / kNplan);
982 pla = ((Int_t) idChamber % kNplan);
984 // The detector number
985 det = fGeometry->GetDetector(pla,cha,sec);
987 // 0: InFlight 1:Entering 2:Exiting
990 // Special hits only in the drift region
992 (gMC->IsTrackEntering())) {
994 // Create a track reference at the entrance of each
995 // chamber that contains the momentum components of the particle
996 gMC->TrackMomentum(mom);
997 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
1000 // Create the hits from TR photons if electron/positron is
1001 // entering the drift volume
1003 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
1008 else if ((amRegion) &&
1009 (gMC->IsTrackExiting())) {
1011 // Create a track reference at the exit of each
1012 // chamber that contains the momentum components of the particle
1013 gMC->TrackMomentum(mom);
1014 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
1019 // Calculate the charge according to GEANT Edep
1020 // Create a new dEdx hit
1021 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1022 qTot = (Int_t) (eDep / kWion);
1025 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1029 ,gMC->TrackTime()*1.0e06
1033 // Set Maximum Step Size
1034 // Produce only one hit if Ekin is below cutoff
1035 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1038 gMC->SetMaxStep(fStepSize);
1042 //_____________________________________________________________________________
1043 Double_t AliTRDv1::BetheBloch(Double_t bg)
1046 // Parametrization of the Bethe-Bloch-curve
1047 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1050 // This parameters have been adjusted to averaged values from GEANT
1051 const Double_t kP1 = 7.17960e-02;
1052 const Double_t kP2 = 8.54196;
1053 const Double_t kP3 = 1.38065e-06;
1054 const Double_t kP4 = 5.30972;
1055 const Double_t kP5 = 2.83798;
1057 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1058 const Double_t kBgMin = 0.8;
1059 const Double_t kBBMax = 6.83298;
1062 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
1063 Double_t aa = TMath::Power(yy,kP4);
1064 Double_t bb = TMath::Power((1.0/bg),kP5);
1065 bb = TMath::Log(kP3 + bb);
1066 return ((kP2 - aa - bb) * kP1 / aa);
1074 //_____________________________________________________________________________
1075 Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
1078 // Return dN/dx (number of primary collisions per centimeter)
1079 // for given beta*gamma factor.
1081 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1082 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1083 // This must be used as a set with IntSpecGeant.
1088 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1089 , 1.800000, 2.000000, 2.500000, 3.000000
1090 , 4.000000, 7.000000, 10.000000, 20.000000
1091 , 40.000000, 70.000000, 100.000000, 300.000000
1092 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
1094 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1095 , 22.734999, 21.411915, 19.934095, 19.449375
1096 , 19.344431, 20.185553, 21.027925, 22.912676
1097 , 24.933352, 26.504053, 27.387468, 29.566597
1098 , 30.353779, 30.787134, 31.129285, 31.157350 };
1100 // Betagamma to gamma
1101 Double_t g = TMath::Sqrt(1.0 + bg*bg);
1103 // Find the index just before the point we need.
1104 for (i = 0; i < 18; i++) {
1105 if ((arrG[i] < g) &&
1111 // Simple interpolation.
1112 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1113 * (g - arrG[i]) + arrNC[i];
1119 //_____________________________________________________________________________
1120 Double_t Ermilova(Double_t *x, Double_t *)
1123 // Calculates the delta-ray energy distribution according to Ermilova.
1124 // Logarithmic scale !
1134 const Int_t kNv = 31;
1136 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1137 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1138 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1139 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1140 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1141 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1144 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1145 , 20.9, 20.8, 20.0, 16.0, 11.0
1146 , 8.0, 6.0, 5.2, 4.6, 4.0
1147 , 3.5, 3.0, 1.4, 0.67, 0.44
1148 , 0.3, 0.18, 0.12, 0.08, 0.056
1149 , 0.04, 0.023, 0.015, 0.011, 0.01
1154 // Find the position
1159 dpos = energy - vxe[pos2++];
1168 // Differentiate between the sampling points
1169 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1175 //_____________________________________________________________________________
1176 Double_t IntSpecGeant(Double_t *x, Double_t *)
1179 // Integrated spectrum from Geant3
1182 const Int_t npts = 83;
1183 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1184 , 2.672067, 2.813299, 3.015059, 3.216819
1185 , 3.418579, 3.620338, 3.868209, 3.920198
1186 , 3.978284, 4.063923, 4.186264, 4.308605
1187 , 4.430946, 4.553288, 4.724261, 4.837736
1188 , 4.999842, 5.161949, 5.324056, 5.486163
1189 , 5.679688, 5.752998, 5.857728, 5.962457
1190 , 6.067185, 6.171914, 6.315653, 6.393674
1191 , 6.471694, 6.539689, 6.597658, 6.655627
1192 , 6.710957, 6.763648, 6.816338, 6.876198
1193 , 6.943227, 7.010257, 7.106285, 7.252151
1194 , 7.460531, 7.668911, 7.877290, 8.085670
1195 , 8.302979, 8.353585, 8.413120, 8.483500
1196 , 8.541030, 8.592857, 8.668865, 8.820485
1197 , 9.037086, 9.253686, 9.470286, 9.686887
1198 , 9.930838, 9.994655, 10.085822, 10.176990
1199 , 10.268158, 10.359325, 10.503614, 10.627565
1200 , 10.804637, 10.981709, 11.158781, 11.335854
1201 , 11.593397, 11.781165, 12.049404, 12.317644
1202 , 12.585884, 12.854123, 14.278421, 16.975889
1203 , 20.829416, 24.682943, 28.536469 };
1205 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1206 , 9.1601500, 8.206670, 6.919630, 5.655430
1207 , 4.6221300, 3.777610, 3.019560, 2.591950
1208 , 2.5414600, 2.712920, 3.327460, 4.928240
1209 , 7.6185300, 10.966700, 12.225800, 8.094750
1210 , 3.3586900, 1.553650, 1.209600, 1.263840
1211 , 1.3241100, 1.312140, 1.255130, 1.165770
1212 , 1.0594500, 0.945450, 0.813231, 0.699837
1213 , 0.6235580, 2.260990, 2.968350, 2.240320
1214 , 1.7988300, 1.553300, 1.432070, 1.535520
1215 , 1.4429900, 1.247990, 1.050750, 0.829549
1216 , 0.5900280, 0.395897, 0.268741, 0.185320
1217 , 0.1292120, 0.103545, 0.0949525, 0.101535
1218 , 0.1276380, 0.134216, 0.123816, 0.104557
1219 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1220 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1221 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1222 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1223 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1224 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1225 , 3.63304e-06, 0.0000000, 0.0000000 };
1228 Double_t energy = x[0];
1230 if (energy >= arre[npts-1]) {
1234 for (i = 0; i < npts; i++) {
1235 if (energy < arre[i]) {
1241 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");