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"
41 #include "AliGeomManager.h"
43 #include "AliTRDgeometry.h"
44 #include "AliTRDhit.h"
45 #include "AliTRDsimTR.h"
50 //_____________________________________________________________________________
55 ,fTypeOfStepManager(0)
63 // Default constructor
68 //_____________________________________________________________________________
69 AliTRDv1::AliTRDv1(const char *name, const char *title)
73 ,fTypeOfStepManager(2)
81 // Standard constructor for Transition Radiation Detector version 1
84 SetBufferSize(128000);
88 //_____________________________________________________________________________
92 // AliTRDv1 destructor
112 //_____________________________________________________________________________
113 void AliTRDv1::AddAlignableVolumes() const
116 // Create entries for alignable volumes associating the symbolic volume
117 // name with the corresponding volume path. Needs to be syncronized with
118 // eventual changes in the geometry.
124 TString vpStr = "ALIC_1/B077_1/BSEGMO";
125 TString vpApp1 = "_1/BTRD";
126 TString vpApp2 = "_1";
127 TString vpApp3a = "/UTR1_1/UTS1_1/UTI1_1/UT";
128 TString vpApp3b = "/UTR2_1/UTS2_1/UTI2_1/UT";
129 TString vpApp3c = "/UTR3_1/UTS3_1/UTI3_1/UT";
131 TString snStr = "TRD/sm";
132 TString snApp1 = "/st";
133 TString snApp2 = "/pl";
137 // The symbolic names are: TRD/sm00
141 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
150 symName += Form("%02d",isect);
152 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data());
157 // The readout chambers
158 // The symbolic names are: TRD/sm00/st0/pl0
162 AliGeomManager::ELayerID idTRD1 = AliGeomManager::kTRD1;
165 for (Int_t isect = 0; isect < AliTRDgeometry::Nsect(); isect++) {
167 if (fGeometry->GetSMstatus(isect) == 0) continue;
169 for (Int_t icham = 0; icham < AliTRDgeometry::Ncham(); icham++) {
170 for (Int_t iplan = 0; iplan < AliTRDgeometry::Nplan(); iplan++) {
172 layer = idTRD1 + iplan;
173 modUID = AliGeomManager::LayerToVolUIDSafe(layer,isect*5+icham);
175 Int_t idet = AliTRDgeometry::GetDetectorSec(iplan,icham);
198 volPath += Form("%02d",idet);
202 symName += Form("%02d",isect);
208 TGeoPNEntry *alignableEntry =
209 gGeoManager->SetAlignableEntry(symName.Data(),volPath.Data(),modUID);
211 // Add the tracking to local matrix following the TPC example
212 if (alignableEntry) {
213 // Is this correct still????
214 TGeoHMatrix *globMatrix = alignableEntry->GetGlobalOrig();
215 Double_t sectorAngle = 20.0 * (isect % 18) + 10.0;
216 TGeoHMatrix *t2lMatrix = new TGeoHMatrix();
217 t2lMatrix->RotateZ(sectorAngle);
218 t2lMatrix->MultiplyLeft(&(globMatrix->Inverse()));
219 alignableEntry->SetMatrix(t2lMatrix);
222 AliError(Form("Alignable entry %s is not valid!",symName.Data()));
231 //_____________________________________________________________________________
232 void AliTRDv1::CreateGeometry()
235 // Create the GEANT geometry for the Transition Radiation Detector - Version 1
236 // This version covers the full azimuth.
239 // Check that FRAME is there otherwise we have no place where to put the TRD
240 AliModule* frame = gAlice->GetModule("FRAME");
242 AliError("TRD needs FRAME to be present\n");
246 // Define the chambers
247 AliTRD::CreateGeometry();
251 //_____________________________________________________________________________
252 void AliTRDv1::CreateMaterials()
255 // Create materials for the Transition Radiation Detector version 1
258 AliTRD::CreateMaterials();
262 //_____________________________________________________________________________
263 void AliTRDv1::CreateTRhit(Int_t det)
266 // Creates an electron cluster from a TR photon.
267 // The photon is assumed to be created a the end of the radiator. The
268 // distance after which it deposits its energy takes into account the
269 // absorbtion of the entrance window and of the gas mixture in drift
274 const Float_t kWion = 23.53;
276 // Maximum number of TR photons per track
277 const Int_t kNTR = 50;
286 gMC->TrackMomentum(mom);
287 Float_t pTot = mom.Rho();
288 fTR->CreatePhotons(11,pTot,nTR,eTR);
290 AliFatal(Form("Boundary error: nTR = %d, kNTR = %d",nTR,kNTR));
293 // Loop through the TR photons
294 for (Int_t iTR = 0; iTR < nTR; iTR++) {
296 Float_t energyMeV = eTR[iTR] * 0.001;
297 Float_t energyeV = eTR[iTR] * 1000.0;
298 Float_t absLength = 0.0;
301 // Take the absorbtion in the entrance window into account
302 Double_t muMy = fTR->GetMuMy(energyMeV);
303 sigma = muMy * fFoilDensity;
305 absLength = gRandom->Exp(1.0/sigma);
306 if (absLength < AliTRDgeometry::MyThick()) {
314 // The absorbtion cross sections in the drift gas
315 // Gas-mixture (Xe/CO2)
316 Double_t muXe = fTR->GetMuXe(energyMeV);
317 Double_t muCO = fTR->GetMuCO(energyMeV);
318 sigma = (0.85 * muXe + 0.15 * muCO) * fGasDensity * fTR->GetTemp();
320 // The distance after which the energy of the TR photon
323 absLength = gRandom->Exp(1.0/sigma);
324 if (absLength > (AliTRDgeometry::DrThick()
325 + AliTRDgeometry::AmThick())) {
333 // The position of the absorbtion
335 gMC->TrackPosition(pos);
336 posHit[0] = pos[0] + mom[0] / pTot * absLength;
337 posHit[1] = pos[1] + mom[1] / pTot * absLength;
338 posHit[2] = pos[2] + mom[2] / pTot * absLength;
341 Int_t q = ((Int_t) (energyeV / kWion));
343 // Add the hit to the array. TR photon hits are marked
344 // by negative charge
345 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
349 ,gMC->TrackTime()*1.0e06
356 //_____________________________________________________________________________
357 void AliTRDv1::Init()
360 // Initialise Transition Radiation Detector after geometry has been built.
365 AliDebug(1,"Slow simulator\n");
367 // Switch on TR simulation as default
369 AliInfo("TR simulation off");
372 fTR = new AliTRDsimTR();
375 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
376 const Float_t kPoti = 12.1;
377 // Maximum energy (50 keV);
378 const Float_t kEend = 50000.0;
379 // Ermilova distribution for the delta-ray spectrum
380 Float_t poti = TMath::Log(kPoti);
381 Float_t eEnd = TMath::Log(kEend);
383 // Ermilova distribution for the delta-ray spectrum
384 fDeltaE = new TF1("deltae" ,Ermilova ,poti,eEnd,0);
386 // Geant3 distribution for the delta-ray spectrum
387 fDeltaG = new TF1("deltag",IntSpecGeant,2.421257,28.536469,0);
389 AliDebug(1,"+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++");
393 //_____________________________________________________________________________
394 void AliTRDv1::StepManager()
397 // Slow simulator. Every charged track produces electron cluster as hits
398 // along its path across the drift volume.
401 switch (fTypeOfStepManager) {
403 StepManagerErmilova();
409 StepManagerFixedStep();
412 AliWarning("Not a valid Step Manager.");
417 //_____________________________________________________________________________
418 void AliTRDv1::SelectStepManager(Int_t t)
421 // Selects a step manager type:
424 // 2 - Fixed step size
427 fTypeOfStepManager = t;
428 AliInfo(Form("Step Manager type %d was selected",fTypeOfStepManager));
432 //_____________________________________________________________________________
433 void AliTRDv1::StepManagerGeant()
436 // Slow simulator. Every charged track produces electron cluster as hits
437 // along its path across the drift volume. The step size is set acording
438 // to Bethe-Bloch. The energy distribution of the delta electrons follows
439 // a spectrum taken from Geant3.
441 // Version by A. Bercuci
459 Double_t stepSize = 0;
461 Bool_t drRegion = kFALSE;
462 Bool_t amRegion = kFALSE;
469 TString cIdSensDr = "J";
470 TString cIdSensAm = "K";
471 Char_t cIdChamber[3];
479 const Int_t kNplan = AliTRDgeometry::Nplan();
480 const Int_t kNcham = AliTRDgeometry::Ncham();
481 const Int_t kNdetsec = kNplan * kNcham;
483 const Double_t kBig = 1.0e+12; // Infinitely big
484 const Float_t kWion = 23.53; // Ionization energy
485 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
487 // Minimum energy for the step size adjustment
488 const Float_t kEkinMinStep = 1.0e-5;
489 // energy threshold for production of delta electrons
490 const Float_t kECut = 1.0e4;
491 // Parameters entering the parametrized range for delta electrons
492 const Float_t kRa = 5.37e-4;
493 const Float_t kRb = 0.9815;
494 const Float_t kRc = 3.123e-3;
495 // Gas density -> To be made user adjustable !
496 // [0.85*0.00549+0.15*0.00186 (Xe-CO2 85-15)]
497 const Float_t kRho = 0.004945 ;
499 // Plateau value of the energy-loss for electron in xenon
500 // The averaged value (26/3/99)
501 const Float_t kPlateau = 1.55;
502 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
503 const Float_t kPrim = 19.34;
504 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
505 const Float_t kPoti = 12.1;
507 const Int_t kPdgElectron = 11;
509 // Set the maximum step size to a very large number for all
510 // neutral particles and those outside the driftvolume
511 gMC->SetMaxStep(kBig);
513 // Use only charged tracks
514 if (( gMC->TrackCharge() ) &&
515 (!gMC->IsTrackDisappeared())) {
517 // Inside a sensitive volume?
520 cIdCurrent = gMC->CurrentVolName();
521 if (cIdSensDr == cIdCurrent[1]) {
524 if (cIdSensAm == cIdCurrent[1]) {
527 if (drRegion || amRegion) {
529 // The hit coordinates and charge
530 gMC->TrackPosition(pos);
535 // The sector number (0 - 17), according to standard coordinate system
536 cIdPath = gGeoManager->GetPath();
537 cIdSector[0] = cIdPath[21];
538 cIdSector[1] = cIdPath[22];
539 sec = atoi(cIdSector);
541 // The plane and chamber number
542 cIdChamber[0] = cIdCurrent[2];
543 cIdChamber[1] = cIdCurrent[3];
544 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
545 cha = ((Int_t) idChamber / kNplan);
546 pla = ((Int_t) idChamber % kNplan);
548 // The detector number
549 det = fGeometry->GetDetector(pla,cha,sec);
551 // Special hits only in the drift region
553 (gMC->IsTrackEntering())) {
555 // Create a track reference at the entrance of each
556 // chamber that contains the momentum components of the particle
557 gMC->TrackMomentum(mom);
558 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
560 // Create the hits from TR photons if electron/positron is
561 // entering the drift volume
563 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
568 else if ((amRegion) &&
569 (gMC->IsTrackExiting())) {
571 // Create a track reference at the exit of each
572 // chamber that contains the momentum components of the particle
573 gMC->TrackMomentum(mom);
574 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
578 // Calculate the energy of the delta-electrons
579 // modified by Alex Bercuci (A.Bercuci@gsi.de) on 26.01.06
580 // take into account correlation with the underlying GEANT tracking
582 // http://www-linux.gsi.de/~abercuci/Contributions/TRD/index.html
584 // determine the most significant process (last on the processes list)
585 // which caused this hit
586 gMC->StepProcesses(processes);
587 Int_t nofprocesses = processes.GetSize();
593 pid = processes[nofprocesses-1];
596 // Generate Edep according to GEANT parametrisation
597 eDelta = TMath::Exp(fDeltaG->GetRandom()) - kPoti;
598 eDelta = TMath::Max(eDelta,0.0);
599 Float_t prRange = 0.0;
600 Float_t range = gMC->TrackLength() - fTrackLength0;
601 // merge GEANT tracker information with locally cooked one
602 if (gAlice->GetMCApp()->GetCurrentTrackNumber() == fPrimaryTrackPid) {
604 if (eDelta >= kECut) {
605 prRange = kRa * eDelta * 0.001
606 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
607 if (prRange >= (3.7 - range)) {
613 if (eDelta < kECut) {
617 prRange = kRa * eDelta * 0.001
618 * (1.0 - kRb / (1.0 + kRc * eDelta * 0.001)) / kRho;
619 if (prRange >= ((AliTRDgeometry::DrThick()
620 + AliTRDgeometry::AmThick()) - range)) {
636 // Generate the electron cluster size
639 qTot = ((Int_t) (eDelta / kWion) + 1);
641 // Create a new dEdx hit
642 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
646 ,gMC->TrackTime()*1.0e06
651 // Calculate the maximum step size for the next tracking step
652 // Produce only one hit if Ekin is below cutoff
653 aMass = gMC->TrackMass();
654 if ((gMC->Etot() - aMass) > kEkinMinStep) {
656 // The energy loss according to Bethe Bloch
657 iPdg = TMath::Abs(gMC->TrackPid());
658 if ((iPdg != kPdgElectron) ||
659 ((iPdg == kPdgElectron) &&
660 (pTot < kPTotMaxEl))) {
661 gMC->TrackMomentum(mom);
663 betaGamma = pTot / aMass;
664 pp = BetheBlochGeant(betaGamma);
665 // Take charge > 1 into account
666 charge = gMC->TrackCharge();
667 if (TMath::Abs(charge) > 1) {
668 pp = pp * charge*charge;
672 // Electrons above 20 Mev/c are at the plateau
673 pp = kPrim * kPlateau;
678 nsteps = gRandom->Poisson(pp);
680 stepSize = 1.0 / nsteps;
681 gMC->SetMaxStep(stepSize);
691 //_____________________________________________________________________________
692 void AliTRDv1::StepManagerErmilova()
695 // Slow simulator. Every charged track produces electron cluster as hits
696 // along its path across the drift volume. The step size is set acording
697 // to Bethe-Bloch. The energy distribution of the delta electrons follows
698 // a spectrum taken from Ermilova et al.
719 Bool_t drRegion = kFALSE;
720 Bool_t amRegion = kFALSE;
727 TString cIdSensDr = "J";
728 TString cIdSensAm = "K";
729 Char_t cIdChamber[3];
735 const Int_t kNplan = AliTRDgeometry::Nplan();
736 const Int_t kNcham = AliTRDgeometry::Ncham();
737 const Int_t kNdetsec = kNplan * kNcham;
739 const Double_t kBig = 1.0e+12; // Infinitely big
740 const Float_t kWion = 23.53; // Ionization energy
741 const Float_t kPTotMaxEl = 0.002; // Maximum momentum for e+ e- g
743 // Minimum energy for the step size adjustment
744 const Float_t kEkinMinStep = 1.0e-5;
746 // Plateau value of the energy-loss for electron in xenon
747 // The averaged value (26/3/99)
748 const Float_t kPlateau = 1.55;
749 // dN1/dx|min for the gas mixture (90% Xe + 10% CO2)
750 const Float_t kPrim = 48.0;
751 // First ionization potential (eV) for the gas mixture (90% Xe + 10% CO2)
752 const Float_t kPoti = 12.1;
754 const Int_t kPdgElectron = 11;
756 // Set the maximum step size to a very large number for all
757 // neutral particles and those outside the driftvolume
758 gMC->SetMaxStep(kBig);
760 // Use only charged tracks
761 if (( gMC->TrackCharge() ) &&
762 (!gMC->IsTrackDisappeared())) {
764 // Inside a sensitive volume?
767 cIdCurrent = gMC->CurrentVolName();
768 if (cIdSensDr == cIdCurrent[1]) {
771 if (cIdSensAm == cIdCurrent[1]) {
774 if (drRegion || amRegion) {
776 // The hit coordinates and charge
777 gMC->TrackPosition(pos);
782 // The sector number (0 - 17), according to standard coordinate system
783 cIdPath = gGeoManager->GetPath();
784 cIdSector[0] = cIdPath[21];
785 cIdSector[1] = cIdPath[22];
786 sec = atoi(cIdSector);
788 // The plane and chamber number
789 cIdChamber[0] = cIdCurrent[2];
790 cIdChamber[1] = cIdCurrent[3];
791 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
792 cha = ((Int_t) idChamber / kNplan);
793 pla = ((Int_t) idChamber % kNplan);
795 // The detector number
796 det = fGeometry->GetDetector(pla,cha,sec);
798 // Special hits only in the drift region
800 (gMC->IsTrackEntering())) {
802 // Create a track reference at the entrance of each
803 // chamber that contains the momentum components of the particle
804 gMC->TrackMomentum(mom);
805 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
807 // Create the hits from TR photons if electron/positron is
808 // entering the drift volume
810 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
815 else if ((amRegion) &&
816 (gMC->IsTrackExiting())) {
818 // Create a track reference at the exit of each
819 // chamber that contains the momentum components of the particle
820 gMC->TrackMomentum(mom);
821 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
825 // Calculate the energy of the delta-electrons
826 eDelta = TMath::Exp(fDeltaE->GetRandom()) - kPoti;
827 eDelta = TMath::Max(eDelta,0.0);
829 // Generate the electron cluster size
832 qTot = ((Int_t) (eDelta / kWion) + 1);
834 // Create a new dEdx hit
836 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
840 ,gMC->TrackTime()*1.0e06
844 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
848 ,gMC->TrackTime()*1.0e06
854 // Calculate the maximum step size for the next tracking step
855 // Produce only one hit if Ekin is below cutoff
856 aMass = gMC->TrackMass();
857 if ((gMC->Etot() - aMass) > kEkinMinStep) {
859 // The energy loss according to Bethe Bloch
860 iPdg = TMath::Abs(gMC->TrackPid());
861 if ((iPdg != kPdgElectron) ||
862 ((iPdg == kPdgElectron) &&
863 (pTot < kPTotMaxEl))) {
864 gMC->TrackMomentum(mom);
866 betaGamma = pTot / aMass;
867 pp = kPrim * BetheBloch(betaGamma);
868 // Take charge > 1 into account
869 charge = gMC->TrackCharge();
870 if (TMath::Abs(charge) > 1) {
871 pp = pp * charge*charge;
875 // Electrons above 20 Mev/c are at the plateau
876 pp = kPrim * kPlateau;
881 gMC->GetRandom()->RndmArray(1,random);
883 while ((random[0] == 1.0) ||
885 stepSize = - TMath::Log(random[0]) / pp;
886 gMC->SetMaxStep(stepSize);
897 //_____________________________________________________________________________
898 void AliTRDv1::StepManagerFixedStep()
901 // Slow simulator. Every charged track produces electron cluster as hits
902 // along its path across the drift volume. The step size is fixed in
903 // this version of the step manager.
907 const Int_t kPdgElectron = 11;
918 Bool_t drRegion = kFALSE;
919 Bool_t amRegion = kFALSE;
926 TString cIdSensDr = "J";
927 TString cIdSensAm = "K";
928 Char_t cIdChamber[3];
934 const Int_t kNplan = AliTRDgeometry::Nplan();
935 const Int_t kNcham = AliTRDgeometry::Ncham();
936 const Int_t kNdetsec = kNplan * kNcham;
938 const Double_t kBig = 1.0e+12;
940 const Float_t kWion = 23.53; // Ionization energy
941 const Float_t kEkinMinStep = 1.0e-5; // Minimum energy for the step size adjustment
943 // Set the maximum step size to a very large number for all
944 // neutral particles and those outside the driftvolume
945 gMC->SetMaxStep(kBig);
947 // If not charged track or already stopped or disappeared, just return.
948 if ((!gMC->TrackCharge()) ||
949 gMC->IsTrackDisappeared()) {
953 // Inside a sensitive volume?
954 cIdCurrent = gMC->CurrentVolName();
956 if (cIdSensDr == cIdCurrent[1]) {
959 if (cIdSensAm == cIdCurrent[1]) {
968 // The hit coordinates and charge
969 gMC->TrackPosition(pos);
974 // The sector number (0 - 17), according to standard coordinate system
975 cIdPath = gGeoManager->GetPath();
976 cIdSector[0] = cIdPath[21];
977 cIdSector[1] = cIdPath[22];
978 sec = atoi(cIdSector);
980 // The plane and chamber number
981 cIdChamber[0] = cIdCurrent[2];
982 cIdChamber[1] = cIdCurrent[3];
983 Int_t idChamber = (atoi(cIdChamber) % kNdetsec);
984 cha = ((Int_t) idChamber / kNplan);
985 pla = ((Int_t) idChamber % kNplan);
987 // The detector number
988 det = fGeometry->GetDetector(pla,cha,sec);
990 // 0: InFlight 1:Entering 2:Exiting
993 // Special hits only in the drift region
995 (gMC->IsTrackEntering())) {
997 // Create a track reference at the entrance of each
998 // chamber that contains the momentum components of the particle
999 gMC->TrackMomentum(mom);
1000 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
1003 // Create the hits from TR photons if electron/positron is
1004 // entering the drift volume
1006 (TMath::Abs(gMC->TrackPid()) == kPdgElectron)) {
1011 else if ((amRegion) &&
1012 (gMC->IsTrackExiting())) {
1014 // Create a track reference at the exit of each
1015 // chamber that contains the momentum components of the particle
1016 gMC->TrackMomentum(mom);
1017 AddTrackReference(gAlice->GetMCApp()->GetCurrentTrackNumber(), AliTrackReference::kTRD);
1022 // Calculate the charge according to GEANT Edep
1023 // Create a new dEdx hit
1024 eDep = TMath::Max(gMC->Edep(),0.0) * 1.0e+09;
1025 qTot = (Int_t) (eDep / kWion);
1028 AddHit(gAlice->GetMCApp()->GetCurrentTrackNumber()
1032 ,gMC->TrackTime()*1.0e06
1036 // Set Maximum Step Size
1037 // Produce only one hit if Ekin is below cutoff
1038 if ((gMC->Etot() - gMC->TrackMass()) < kEkinMinStep) {
1041 gMC->SetMaxStep(fStepSize);
1045 //_____________________________________________________________________________
1046 Double_t AliTRDv1::BetheBloch(Double_t bg)
1049 // Parametrization of the Bethe-Bloch-curve
1050 // The parametrization is the same as for the TPC and is taken from Lehrhaus.
1053 // This parameters have been adjusted to averaged values from GEANT
1054 const Double_t kP1 = 7.17960e-02;
1055 const Double_t kP2 = 8.54196;
1056 const Double_t kP3 = 1.38065e-06;
1057 const Double_t kP4 = 5.30972;
1058 const Double_t kP5 = 2.83798;
1060 // Lower cutoff of the Bethe-Bloch-curve to limit step sizes
1061 const Double_t kBgMin = 0.8;
1062 const Double_t kBBMax = 6.83298;
1065 Double_t yy = bg / TMath::Sqrt(1.0 + bg*bg);
1066 Double_t aa = TMath::Power(yy,kP4);
1067 Double_t bb = TMath::Power((1.0/bg),kP5);
1068 bb = TMath::Log(kP3 + bb);
1069 return ((kP2 - aa - bb) * kP1 / aa);
1077 //_____________________________________________________________________________
1078 Double_t AliTRDv1::BetheBlochGeant(Double_t bg)
1081 // Return dN/dx (number of primary collisions per centimeter)
1082 // for given beta*gamma factor.
1084 // Implemented by K.Oyama according to GEANT 3 parametrization shown in
1085 // A.Andronic's webpage: http://www-alice.gsi.de/trd/papers/dedx/dedx.html
1086 // This must be used as a set with IntSpecGeant.
1091 Double_t arrG[20] = { 1.100000, 1.200000, 1.300000, 1.500000
1092 , 1.800000, 2.000000, 2.500000, 3.000000
1093 , 4.000000, 7.000000, 10.000000, 20.000000
1094 , 40.000000, 70.000000, 100.000000, 300.000000
1095 , 600.000000, 1000.000000, 3000.000000, 10000.000000 };
1097 Double_t arrNC[20] = { 75.009056, 45.508083, 35.299252, 27.116327
1098 , 22.734999, 21.411915, 19.934095, 19.449375
1099 , 19.344431, 20.185553, 21.027925, 22.912676
1100 , 24.933352, 26.504053, 27.387468, 29.566597
1101 , 30.353779, 30.787134, 31.129285, 31.157350 };
1103 // Betagamma to gamma
1104 Double_t g = TMath::Sqrt(1.0 + bg*bg);
1106 // Find the index just before the point we need.
1107 for (i = 0; i < 18; i++) {
1108 if ((arrG[i] < g) &&
1114 // Simple interpolation.
1115 Double_t pp = ((arrNC[i+1] - arrNC[i]) / (arrG[i+1] - arrG[i]))
1116 * (g - arrG[i]) + arrNC[i];
1122 //_____________________________________________________________________________
1123 Double_t Ermilova(Double_t *x, Double_t *)
1126 // Calculates the delta-ray energy distribution according to Ermilova.
1127 // Logarithmic scale !
1137 const Int_t kNv = 31;
1139 Float_t vxe[kNv] = { 2.3026, 2.9957, 3.4012, 3.6889, 3.9120
1140 , 4.0943, 4.2485, 4.3820, 4.4998, 4.6052
1141 , 4.7005, 5.0752, 5.2983, 5.7038, 5.9915
1142 , 6.2146, 6.5221, 6.9078, 7.3132, 7.6009
1143 , 8.0064, 8.5172, 8.6995, 8.9872, 9.2103
1144 , 9.4727, 9.9035, 10.3735, 10.5966, 10.8198
1147 Float_t vye[kNv] = { 80.0, 31.0, 23.3, 21.1, 21.0
1148 , 20.9, 20.8, 20.0, 16.0, 11.0
1149 , 8.0, 6.0, 5.2, 4.6, 4.0
1150 , 3.5, 3.0, 1.4, 0.67, 0.44
1151 , 0.3, 0.18, 0.12, 0.08, 0.056
1152 , 0.04, 0.023, 0.015, 0.011, 0.01
1157 // Find the position
1162 dpos = energy - vxe[pos2++];
1171 // Differentiate between the sampling points
1172 dnde = (vye[pos1] - vye[pos2]) / (vxe[pos2] - vxe[pos1]);
1178 //_____________________________________________________________________________
1179 Double_t IntSpecGeant(Double_t *x, Double_t *)
1182 // Integrated spectrum from Geant3
1185 const Int_t npts = 83;
1186 Double_t arre[npts] = { 2.421257, 2.483278, 2.534301, 2.592230
1187 , 2.672067, 2.813299, 3.015059, 3.216819
1188 , 3.418579, 3.620338, 3.868209, 3.920198
1189 , 3.978284, 4.063923, 4.186264, 4.308605
1190 , 4.430946, 4.553288, 4.724261, 4.837736
1191 , 4.999842, 5.161949, 5.324056, 5.486163
1192 , 5.679688, 5.752998, 5.857728, 5.962457
1193 , 6.067185, 6.171914, 6.315653, 6.393674
1194 , 6.471694, 6.539689, 6.597658, 6.655627
1195 , 6.710957, 6.763648, 6.816338, 6.876198
1196 , 6.943227, 7.010257, 7.106285, 7.252151
1197 , 7.460531, 7.668911, 7.877290, 8.085670
1198 , 8.302979, 8.353585, 8.413120, 8.483500
1199 , 8.541030, 8.592857, 8.668865, 8.820485
1200 , 9.037086, 9.253686, 9.470286, 9.686887
1201 , 9.930838, 9.994655, 10.085822, 10.176990
1202 , 10.268158, 10.359325, 10.503614, 10.627565
1203 , 10.804637, 10.981709, 11.158781, 11.335854
1204 , 11.593397, 11.781165, 12.049404, 12.317644
1205 , 12.585884, 12.854123, 14.278421, 16.975889
1206 , 20.829416, 24.682943, 28.536469 };
1208 Double_t arrdnde[npts] = { 10.960000, 10.960000, 10.359500, 9.811340
1209 , 9.1601500, 8.206670, 6.919630, 5.655430
1210 , 4.6221300, 3.777610, 3.019560, 2.591950
1211 , 2.5414600, 2.712920, 3.327460, 4.928240
1212 , 7.6185300, 10.966700, 12.225800, 8.094750
1213 , 3.3586900, 1.553650, 1.209600, 1.263840
1214 , 1.3241100, 1.312140, 1.255130, 1.165770
1215 , 1.0594500, 0.945450, 0.813231, 0.699837
1216 , 0.6235580, 2.260990, 2.968350, 2.240320
1217 , 1.7988300, 1.553300, 1.432070, 1.535520
1218 , 1.4429900, 1.247990, 1.050750, 0.829549
1219 , 0.5900280, 0.395897, 0.268741, 0.185320
1220 , 0.1292120, 0.103545, 0.0949525, 0.101535
1221 , 0.1276380, 0.134216, 0.123816, 0.104557
1222 , 0.0751843, 0.0521745, 0.0373546, 0.0275391
1223 , 0.0204713, 0.0169234, 0.0154552, 0.0139194
1224 , 0.0125592, 0.0113638, 0.0107354, 0.0102137
1225 , 0.00845984, 0.00683338, 0.00556836, 0.00456874
1226 , 0.0036227, 0.00285991, 0.00226664, 0.00172234
1227 , 0.00131226, 0.00100284, 0.000465492, 7.26607e-05
1228 , 3.63304e-06, 0.0000000, 0.0000000 };
1231 Double_t energy = x[0];
1233 if (energy >= arre[npts-1]) {
1237 for (i = 0; i < npts; i++) {
1238 if (energy < arre[i]) {
1244 AliErrorGeneral("AliTRDv1::IntSpecGeant","Given energy value is too small or zero");