/************************************************************************** * 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. * **************************************************************************/ /* $Id$ */ #include #include #include #include #include #include #include #include "AliConst.h" #include "AliGenZDC.h" #include "AliRun.h" #include "AliMC.h" ClassImp(AliGenZDC) //_____________________________________________________________________________ AliGenZDC::AliGenZDC() :AliGenerator() { // // Default constructor // fIpart = 0; } //_____________________________________________________________________________ AliGenZDC::AliGenZDC(Int_t npart) :AliGenerator(npart) { // // Standard constructor // fName = "AliGenZDC"; fTitle = "Generation of Test Particles for ZDCs"; fIpart = kNeutron; fCosx = 0.; fCosy = 0.; fCosz = 1.; fPseudoRapidity = 0.; fFermiflag = 1; // LHC values for beam divergence and crossing angle fBeamDiv = 0.000032; fBeamCrossAngle = 0.0001; fBeamCrossPlane = 2; Int_t i, j; for(i=0; i<201; i++){ fProbintp[i] = 0; fProbintn[i] = 0; } for(j=0; j<3; j++) fPp[i] = 0; fDebugOpt = 0; } //_____________________________________________________________________________ void AliGenZDC::Init() { printf("\n\n AliGenZDC initialization:\n"); printf(" Particle: %d, Track cosines: x = %f, y = %f, z = %f \n", fIpart,fCosx,fCosy,fCosz); printf(" Fermi flag = %d, Beam divergence = %f, Crossing angle " "= %f, Crossing plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle, fBeamCrossPlane); //Initialize Fermi momentum distributions for Pb-Pb FermiTwoGaussian(207.,fPp,fProbintp,fProbintn); } //_____________________________________________________________________________ void AliGenZDC::Generate() { // // Generate one trigger (n or p) // Int_t i; Double_t Mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3]; Float_t fPTrack[3], ptot = fPMin; Int_t nt; if(fPseudoRapidity==0.){ pLab[0] = ptot*fCosx; pLab[1] = ptot*fCosy; pLab[2] = ptot*fCosz; } else{ Float_t scang = 2*TMath::ATan(TMath::Exp(-(fPseudoRapidity))); pLab[0] = -ptot*TMath::Sin(scang); pLab[1] = 0.; pLab[2] = ptot*TMath::Cos(scang); } for(i=0; i<=2; i++) fP[i] = pLab[i]; if(fDebugOpt == 1){ printf("\n\n Particle momentum before divergence and crossing\n"); for(i=0; i<=2; i++)printf(" pLab[%d] = %f\n",i,pLab[i]); } // Beam divergence and crossing angle if(fBeamCrossAngle!=0.) { BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab); for(i=0; i<=2; i++) fP[i] = pLab[i]; } if(fBeamDiv!=0.) { BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab); for(i=0; i<=2; i++) fP[i] = pLab[i]; } // If required apply the Fermi momentum if(fFermiflag==1){ if((fIpart==kProton) || (fIpart==kNeutron)) ExtractFermi(fIpart,fPp,fProbintp,fProbintn,ddp); Mass=gAlice->PDGDB()->GetParticle(fIpart)->Mass(); fP0 = TMath::Sqrt(fP[0]*fP[0]+fP[1]*fP[1]+fP[2]*fP[2]+Mass*Mass); for(i=0; i<=2; i++) dddp[i] = ddp[i]; dddp0 = TMath::Sqrt(dddp[0]*dddp[0]+dddp[1]*dddp[1]+dddp[2]*dddp[2]+Mass*Mass); TVector3 b(fP[0]/fP0, fP[1]/fP0, fP[2]/fP0); TLorentzVector pFermi(dddp[0], dddp[1], dddp[2], dddp0); pFermi.Boost(b); for(i=0; i<=2; i++){ fBoostP[i] = pFermi[i]; fP[i] = pFermi[i]; } } for(i=0; i<=2; i++) fPTrack[i] = fP[i]; Float_t polar[3] = {0,0,0}; gAlice->GetMCApp()->PushTrack(fTrackIt,-1,fIpart,fPTrack,fOrigin.GetArray(),polar,0, kPPrimary,nt); // ----------------------------------------------------------------------- if(fDebugOpt == 1){ printf("\n\n Track momentum:\n"); printf("\n fPTrack = %f, %f, %f \n",fPTrack[0],fPTrack[1],fPTrack[2]); } else if(fDebugOpt == 2){ FILE *file; if((file = fopen("SpectMomentum.dat","a")) == NULL){ printf("Cannot open file SpectMomentum.dat\n"); return; } fprintf(file," %f \t %f \t %f \n",fPTrack[0],fPTrack[1],fPTrack[2]); fclose(file); } } //_____________________________________________________________________________ void AliGenZDC::FermiTwoGaussian(Float_t A, Double_t *fPp, Double_t *fProbintp, Double_t *fProbintn) { // // Momenta distributions according to the "double-gaussian" // distribution (Ilinov) - equal for protons and neutrons // fProbintp[0] = 0; fProbintn[0] = 0; Double_t sig1 = 0.113; Double_t sig2 = 0.250; Double_t alfa = 0.18*(TMath::Power((A/12.),(Float_t)1/3)); Double_t xk = (2*k2PI)/((1.+alfa)*(TMath::Power(k2PI,1.5))); for(Int_t i=1; i<=200; i++){ Double_t p = i*0.005; fPp[i] = p; Double_t e1 = (p*p)/(2.*sig1*sig1); Double_t e2 = (p*p)/(2.*sig2*sig2); Double_t f1 = TMath::Exp(-(e1)); Double_t f2 = TMath::Exp(-(e2)); Double_t probp = xk*p*p*(f1/(TMath::Power(sig1,3.))+ alfa*f2/(TMath::Power(sig2,3.)))*0.005; fProbintp[i] = fProbintp[i-1] + probp; fProbintn[i] = fProbintp[i]; } if(fDebugOpt == 1){ printf("\n\n Initialization of Fermi momenta distribution \n"); //for(Int_t i=0; i<=200; i++) // printf(" fProbintp[%d] = %f, fProbintn[%d] = %f\n",i,fProbintp[i],i,fProbintn[i]); } } //_____________________________________________________________________________ void AliGenZDC::ExtractFermi(Int_t id, Double_t *fPp, Double_t *fProbintp, Double_t *fProbintn, Double_t *ddp) { // // Compute Fermi momentum for spectator nucleons // Int_t i; Float_t xx = gRandom->Rndm(); assert ( id==kProton || id==kNeutron ); if(id==kProton){ for(i=1; i<=200; i++){ if((xx>=fProbintp[i-1]) && (xx=fProbintn[i-1]) && (xxRndm()); Float_t cost = (1.-2.*(gRandom->Rndm())); Float_t tet = TMath::ACos(cost); ddp[0] = pext*TMath::Sin(tet)*TMath::Cos(phi); ddp[1] = pext*TMath::Sin(tet)*TMath::Sin(phi); ddp[2] = pext*cost; if(fDebugOpt == 1){ printf("\n\n Extraction of Fermi momentum\n"); printf("\n pxFermi = %f pyFermi = %f pzFermi = %f \n",ddp[0],ddp[1],ddp[2]); } } //_____________________________________________________________________________ void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle, Int_t fBeamCrossPlane, Double_t *pLab) { Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum; Double_t rvec; Double_t pmq = 0.; Int_t i; for(i=0; i<=2; i++) pmq = pmq+pLab[i]*pLab[i]; Double_t pmod = TMath::Sqrt(pmq); if(icross==0){ // ##### Beam divergence rvec = gRandom->Gaus(0.0,1.0); tetdiv = fBeamDiv * TMath::Abs(rvec); fidiv = (gRandom->Rndm())*k2PI; } else if(icross==1){ // ##### Crossing angle if(fBeamCrossPlane==0.){ tetdiv = 0.; fidiv = 0.; } else if(fBeamCrossPlane==1.){ // Horizontal crossing plane tetdiv = fBeamCrossAngle; fidiv = 0.; } else if(fBeamCrossPlane==2.){ // Vertical crossing plane tetdiv = fBeamCrossAngle; fidiv = k2PI/4.; } } tetpart = TMath::ATan2(TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1]),pLab[2]); if(pLab[1]!=0. || pLab[0]!=0.) fipart = TMath::ATan2(pLab[1],pLab[0]); else fipart = 0.; if(fipart<0.) {fipart = fipart+k2PI;} tetdiv = tetdiv*kRaddeg; fidiv = fidiv*kRaddeg; tetpart = tetpart*kRaddeg; fipart = fipart*kRaddeg; AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum); tetsum = angleSum[0]; fisum = angleSum[1]; tetsum = tetsum*kDegrad; fisum = fisum*kDegrad; pLab[0] = pmod*TMath::Sin(tetsum)*TMath::Cos(fisum); pLab[1] = pmod*TMath::Sin(tetsum)*TMath::Sin(fisum); pLab[2] = pmod*TMath::Cos(tetsum); if(fDebugOpt == 1){ if(icross==0) printf("\n\n Beam divergence \n"); else printf("\n\n Beam crossing \n"); for(i=0; i<=2; i++)printf(" pLab[%d] = %f\n",i,pLab[i]); } } //_____________________________________________________________________________ void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2, Double_t phi2, Double_t *angleSum) { Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2; Double_t rtetsum, tetsum, fisum; temp = -1.; conv = 180./TMath::ACos(temp); ct1 = TMath::Cos(theta1/conv); st1 = TMath::Sin(theta1/conv); cp1 = TMath::Cos(phi1/conv); sp1 = TMath::Sin(phi1/conv); ct2 = TMath::Cos(theta2/conv); st2 = TMath::Sin(theta2/conv); cp2 = TMath::Cos(phi2/conv); sp2 = TMath::Sin(phi2/conv); cx = ct1*cp1*st2*cp2+st1*cp1*ct2-sp1*st2*sp2; cy = ct1*sp1*st2*cp2+st1*sp1*ct2+cp1*st2*sp2; cz = ct1*ct2-st1*st2*cp2; rtetsum = TMath::ACos(cz); tetsum = conv*rtetsum; if(tetsum==0. || tetsum==180.){ fisum = 0.; return; } temp = cx/TMath::Sin(rtetsum); if(temp>1.) temp=1.; if(temp<-1.) temp=-1.; fisum = conv*TMath::ACos(temp); if(cy<0) {fisum = 360.-fisum;} angleSum[0] = tetsum; angleSum[1] = fisum; }