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 // **************************************************************************
17 #include "AliRICHv1.h"
18 #include "AliRICHParam.h"
19 #include "AliRICHChamber.h"
20 #include <TParticle.h>
22 #include <TVirtualMC.h>
31 //__________________________________________________________________________________________________
32 void AliRICHv1::StepManager()
35 // 3- Ckovs absorbed on Collection electrods
36 // 5- Ckovs absorbed on Cathode wires
37 // 6- Ckovs absorbed on Anod wires
40 static Int_t iCurrentChamber;
41 //history of Cerenkovs
42 if(gMC->TrackPid()==kCerenkov){
43 if( gMC->IsNewTrack() && gMC->CurrentVolID(copy)==gMC->VolId("RRAD")) fCounters(0)++;// 0- Ckovs produced in radiator
44 if(!gMC->IsTrackAlive() && gMC->CurrentVolID(copy)==gMC->VolId("RRAD")) fCounters(1)++;// 1- Ckovs absorbed in radiator
45 if(!gMC->IsTrackAlive() && gMC->CurrentVolID(copy)==gMC->VolId("RRWI")) fCounters(2)++;// 2- Ckovs absorbed in radiator window
46 if(!gMC->IsTrackAlive() && gMC->CurrentVolID(copy)==gMC->VolId("RICH")) fCounters(4)++;// 4- Ckovs absorbed in CH4
50 static TLorentzVector cerX4;
51 if((gMC->TrackPid()==kCerenkov||gMC->TrackPid()==kFeedback)&&gMC->CurrentVolID(copy)==gMC->VolId("RPC ")){//photon in PC
52 if(gMC->Edep()>0){//photon in PC +DE
53 if(IsLostByFresnel()){
54 if(gMC->TrackPid()==kCerenkov) fCounters(7)++;// 7- Ckovs reflected from CsI
58 gMC->TrackPosition(cerX4); gMC->CurrentVolOffID(2,iCurrentChamber);//RICH-RPPF-RPC
60 AddHit(iCurrentChamber,gAlice->GetMCApp()->GetCurrentTrackNumber(),cerX4.Vect(),cerX4.Vect());//HIT for PHOTON in conditions CF+CSI+DE
61 fCounters(8)++;//4- Ckovs converted to electron on CsI
62 GenerateFeedbacks(iCurrentChamber);
63 }//photon in PC and DE >0
66 //Treat charged particles
68 static TLorentzVector mipInX4,mipOutX4;
69 if(gMC->TrackCharge() && gMC->CurrentVolID(copy)==gMC->VolId("RGAP")){//MIP in GAP
70 gMC->CurrentVolOffID(1,iCurrentChamber);//RICH-RGAP
71 if(gMC->IsTrackEntering()||gMC->IsNewTrack()) {//MIP in GAP entering or newly created
73 gMC->TrackPosition(mipInX4);
74 }else if(gMC->IsTrackExiting()||gMC->IsTrackStop()||gMC->IsTrackDisappeared()){//MIP in GAP exiting or disappeared
75 eloss+=gMC->Edep();//take into account last step dEdX
76 gMC->TrackPosition(mipOutX4);
77 AddHit(iCurrentChamber,gAlice->GetMCApp()->GetCurrentTrackNumber(),mipInX4.Vect(),mipOutX4.Vect(),eloss);//HIT for MIP: MIP in GAP Exiting
78 GenerateFeedbacks(iCurrentChamber,eloss);//MIP+GAP+Exit
79 }else//MIP in GAP going inside
83 //__________________________________________________________________________________________________
84 Bool_t AliRICHv1::IsLostByFresnel()
86 // Calculate probability for the photon to be lost by Fresnel reflection.
88 Double_t mom[3],localMom[3];
89 gMC->TrackMomentum(p4); mom[0]=p4(1); mom[1]=p4(2); mom[2]=p4(3);
90 localMom[0]=0; localMom[1]=0; localMom[2]=0;
91 gMC->Gmtod(mom,localMom,2);
92 Double_t localTc = localMom[0]*localMom[0]+localMom[2]*localMom[2];
93 Double_t localTheta = TMath::ATan2(TMath::Sqrt(localTc),localMom[1]);
94 Double_t cotheta = TMath::Abs(TMath::Cos(localTheta));
95 if(gMC->GetRandom()->Rndm() < Fresnel(p4.E()*1e9,cotheta,1)){
96 AliDebug(1,"Photon lost");
101 //__________________________________________________________________________________________________
102 void AliRICHv1::GenerateFeedbacks(Int_t iChamber,Float_t eloss)
104 // Generate FeedBack photons for the current particle. To be invoked from StepManager().
105 // eloss=0 means photon so only pulse height distribution is to be analysed. This one is done in AliRICHParam::TotQdc()
108 gMC->TrackPosition(x4);
109 TVector2 x2=C(iChamber)->Mrs2Pc(x4);//hit position on photocathode plane
111 Int_t sector=P()->Loc2Sec(xspe); if(sector==kBad) return; //hit in dead zone, nothing to produce
112 Int_t iTotQdc=P()->TotQdc(x2,eloss);
113 Int_t iNphotons=gMC->GetRandom()->Poisson(P()->C(iChamber)->AlphaFeedback(sector)*iTotQdc);
114 AliDebug(1,Form("N photons=%i",iNphotons));
116 Float_t cthf, phif, enfp = 0, sthf, e1[3], e2[3], e3[3], vmod, uswop,dir[3], phi,pol[3], mom[4];
118 for(Int_t i=0;i<iNphotons;i++){//feedbacks loop
120 gMC->GetRandom()->RndmArray(2,ranf); //Sample direction
123 sthf = TMath::Sqrt((1 - cthf) * (1 + cthf));
124 phif = ranf[1] * 2 * TMath::Pi();
126 if(Double_t randomNumber=gMC->GetRandom()->Rndm()<=0.57)
128 else if(randomNumber<=0.7)
134 dir[0] = sthf * TMath::Sin(phif); dir[1] = cthf; dir[2] = sthf * TMath::Cos(phif);
135 gMC->Gdtom(dir, mom, 2);
136 mom[0]*=enfp; mom[1]*=enfp; mom[2]*=enfp;
137 mom[3] = TMath::Sqrt(mom[0]*mom[0]+mom[1]*mom[1]+mom[2]*mom[2]);
140 e1[0]= 0; e1[1]=-dir[2]; e1[2]= dir[1];
141 e2[0]=-dir[1]; e2[1]= dir[0]; e2[2]= 0;
142 e3[0]= dir[1]; e3[1]= 0; e3[2]=-dir[0];
145 for(j=0;j<3;j++) vmod+=e1[j]*e1[j];
146 if (!vmod) for(j=0;j<3;j++) {
152 for(j=0;j<3;j++) vmod+=e2[j]*e2[j];
153 if (!vmod) for(j=0;j<3;j++) {
159 vmod=0; for(j=0;j<3;j++) vmod+=e1[j]*e1[j]; vmod=TMath::Sqrt(1/vmod); for(j=0;j<3;j++) e1[j]*=vmod;
160 vmod=0; for(j=0;j<3;j++) vmod+=e2[j]*e2[j]; vmod=TMath::Sqrt(1/vmod); for(j=0;j<3;j++) e2[j]*=vmod;
162 phi = gMC->GetRandom()->Rndm()* 2 * TMath::Pi();
163 for(j=0;j<3;j++) pol[j]=e1[j]*TMath::Sin(phi)+e2[j]*TMath::Cos(phi);
164 gMC->Gdtom(pol, pol, 2);
165 Int_t outputNtracksStored;
166 gAlice->GetMCApp()->PushTrack(1, //do not transport
167 gAlice->GetMCApp()->GetCurrentTrackNumber(),//parent track
169 mom[0],mom[1],mom[2],mom[3], //track momentum
170 x4.X(),x4.Y(),x4.Z(),x4.T(), //track origin
171 pol[0],pol[1],pol[2], //polarization
177 }//GenerateFeedbacks()