// ************************************************************************** // * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. * // * * // * Author: The ALICE Off-line Project. * // * Contributors are mentioned in the code where appropriate. * // * * // * Permission to use, copy, modify and distribute this software and its * // * documentation strictly for non-commercial purposes is hereby granted * // * without fee, provided that the above copyright notice appears in all * // * copies and that both the copyright notice and this permission notice * // * appear in the supporting documentation. The authors make no claims * // * about the suitability of this software for any purpose. It is * // * provided "as is" without express or implied warranty. * // ************************************************************************** #include "AliRICHv1.h" #include "AliRICHParam.h" #include "AliRICHChamber.h" #include #include #include #include #include #include #include #include ClassImp(AliRICHv1) //__________________________________________________________________________________________________ void AliRICHv1::StepManager() { // Full Step Manager. // 3- Ckovs absorbed on Collection electrods // 5- Ckovs absorbed on Cathode wires // 6- Ckovs absorbed on Anod wires Int_t copy; static Int_t iCurrentChamber; static Int_t idRRAD = gMC->VolId("RRAD"); static Int_t idRRWI = gMC->VolId("RRWI"); static Int_t idRICH = gMC->VolId("RICH"); static Int_t idRPC = gMC->VolId("RPC "); static Int_t idRGAP = gMC->VolId("RGAP"); //history of Cerenkovs if(gMC->TrackPid()==kCerenkov){ if( gMC->IsNewTrack() && gMC->CurrentVolID(copy)==idRRAD) fCounters(0)++;// 0- Ckovs produced in radiator if(!gMC->IsTrackAlive() && gMC->CurrentVolID(copy)==idRRAD) fCounters(1)++;// 1- Ckovs absorbed in radiator if(!gMC->IsTrackAlive() && gMC->CurrentVolID(copy)==idRRWI) fCounters(2)++;// 2- Ckovs absorbed in radiator window if(!gMC->IsTrackAlive() && gMC->CurrentVolID(copy)==idRICH) fCounters(4)++;// 4- Ckovs absorbed in CH4 } //Treat photons static TLorentzVector cerX4; if((gMC->TrackPid()==kCerenkov||gMC->TrackPid()==kFeedback)&&gMC->CurrentVolID(copy)==idRPC){//photon in PC if(gMC->Edep()>0){//photon in PC +DE if(IsLostByFresnel()){ if(gMC->TrackPid()==kCerenkov) fCounters(7)++;// 7- Ckovs reflected from CsI gMC->StopTrack(); return; } gMC->TrackPosition(cerX4); gMC->CurrentVolOffID(2,iCurrentChamber);//RICH-RPPF-RPC AddHit(iCurrentChamber,gAlice->GetMCApp()->GetCurrentTrackNumber(),cerX4.Vect(),cerX4.Vect());//HIT for PHOTON in conditions CF+CSI+DE fCounters(8)++;//4- Ckovs converted to electron on CsI GenerateFeedbacks(iCurrentChamber); }//photon in PC and DE >0 }//photon in PC //Treat charged particles static Float_t eloss; static TLorentzVector mipInX4,mipOutX4; if(gMC->TrackCharge() && gMC->CurrentVolID(copy)==idRGAP){//MIP in GAP gMC->CurrentVolOffID(1,iCurrentChamber);//RICH-RGAP if(gMC->IsTrackEntering()||gMC->IsNewTrack()) {//MIP in GAP entering or newly created eloss=0; gMC->TrackPosition(mipInX4); }else if(gMC->IsTrackExiting()||gMC->IsTrackStop()||gMC->IsTrackDisappeared()){//MIP in GAP exiting or disappeared eloss+=gMC->Edep();//take into account last step dEdX gMC->TrackPosition(mipOutX4); AddHit(iCurrentChamber,gAlice->GetMCApp()->GetCurrentTrackNumber(),mipInX4.Vect(),mipOutX4.Vect(),eloss);//HIT for MIP: MIP in GAP Exiting GenerateFeedbacks(iCurrentChamber,eloss);//MIP+GAP+Exit }else//MIP in GAP going inside eloss += gMC->Edep(); }//MIP in GAP }//StepManager() //__________________________________________________________________________________________________ Bool_t AliRICHv1::IsLostByFresnel() { // Calculate probability for the photon to be lost by Fresnel reflection. TLorentzVector p4; Double_t mom[3],localMom[3]; gMC->TrackMomentum(p4); mom[0]=p4(1); mom[1]=p4(2); mom[2]=p4(3); localMom[0]=0; localMom[1]=0; localMom[2]=0; gMC->Gmtod(mom,localMom,2); Double_t localTc = localMom[0]*localMom[0]+localMom[2]*localMom[2]; Double_t localTheta = TMath::ATan2(TMath::Sqrt(localTc),localMom[1]); Double_t cotheta = TMath::Abs(TMath::Cos(localTheta)); if(gMC->GetRandom()->Rndm() < Fresnel(p4.E()*1e9,cotheta,1)){ AliDebug(1,"Photon lost"); return kTRUE; }else return kFALSE; }//IsLostByFresnel() //__________________________________________________________________________________________________ void AliRICHv1::GenerateFeedbacks(Int_t iChamber,Float_t eloss) { // Generate FeedBack photons for the current particle. To be invoked from StepManager(). // eloss=0 means photon so only pulse height distribution is to be analysed. This one is done in AliRICHParam::TotQdc() TLorentzVector x4; gMC->TrackPosition(x4); TVector2 x2=C(iChamber)->Mrs2Pc(x4);//hit position on photocathode plane TVector2 xspe=x2; Int_t sector=P()->Loc2Sec(xspe); if(sector==kBad) return; //hit in dead zone, nothing to produce Int_t iTotQdc=P()->TotQdc(x2,eloss); Int_t iNphotons=gMC->GetRandom()->Poisson(P()->C(iChamber)->AlphaFeedback(sector)*iTotQdc); AliDebug(1,Form("N photons=%i",iNphotons)); Int_t j; Float_t cthf, phif, enfp = 0, sthf, e1[3], e2[3], e3[3], vmod, uswop,dir[3], phi,pol[3], mom[4]; //Generate photons for(Int_t i=0;iGetRandom()->RndmArray(2,ranf); //Sample direction cthf=ranf[0]*2-1.0; if(cthf<0) continue; sthf = TMath::Sqrt((1 - cthf) * (1 + cthf)); phif = ranf[1] * 2 * TMath::Pi(); if(Double_t randomNumber=gMC->GetRandom()->Rndm()<=0.57) enfp = 7.5e-9; else if(randomNumber<=0.7) enfp = 6.4e-9; else enfp = 7.9e-9; dir[0] = sthf * TMath::Sin(phif); dir[1] = cthf; dir[2] = sthf * TMath::Cos(phif); gMC->Gdtom(dir, mom, 2); mom[0]*=enfp; mom[1]*=enfp; mom[2]*=enfp; mom[3] = TMath::Sqrt(mom[0]*mom[0]+mom[1]*mom[1]+mom[2]*mom[2]); // Polarisation e1[0]= 0; e1[1]=-dir[2]; e1[2]= dir[1]; e2[0]=-dir[1]; e2[1]= dir[0]; e2[2]= 0; e3[0]= dir[1]; e3[1]= 0; e3[2]=-dir[0]; vmod=0; for(j=0;j<3;j++) vmod+=e1[j]*e1[j]; if (!vmod) for(j=0;j<3;j++) { uswop=e1[j]; e1[j]=e3[j]; e3[j]=uswop; } vmod=0; for(j=0;j<3;j++) vmod+=e2[j]*e2[j]; if (!vmod) for(j=0;j<3;j++) { uswop=e2[j]; e2[j]=e3[j]; e3[j]=uswop; } 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; 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; phi = gMC->GetRandom()->Rndm()* 2 * TMath::Pi(); for(j=0;j<3;j++) pol[j]=e1[j]*TMath::Sin(phi)+e2[j]*TMath::Cos(phi); gMC->Gdtom(pol, pol, 2); Int_t outputNtracksStored; gAlice->GetMCApp()->PushTrack(1, //do not transport gAlice->GetMCApp()->GetCurrentTrackNumber(),//parent track kFeedback, //PID mom[0],mom[1],mom[2],mom[3], //track momentum x4.X(),x4.Y(),x4.Z(),x4.T(), //track origin pol[0],pol[1],pol[2], //polarization kPFeedBackPhoton, outputNtracksStored, 1.0); }//feedbacks loop AliDebug(1,"Stop."); }//GenerateFeedbacks()