/* $Id$ */
+//////////////////////////////////////////////////////////////////////
+// // //
+// Generator of spectator nucleons (either protons or neutrons)//
+// computes beam crossing and divergence and Fermi momentum //
+// //
+/////////////////////////////////////////////////////////////////////
+
#include <assert.h>
#include <TDatabasePDG.h>
//_____________________________________________________________________________
AliGenZDC::AliGenZDC()
- :AliGenerator()
+ :AliGenerator(),
+ fIpart(0),
+ fCosx(0),
+ fCosy(0),
+ fCosz(0),
+ fPseudoRapidity(0),
+ fFermiflag(0),
+ fBeamDiv(0),
+ fBeamCrossAngle(0),
+ fBeamCrossPlane(0),
+ fDebugOpt(0)
{
//
// Default constructor
//
- fIpart = 0;
+ for(Int_t i=0; i<201; i++){
+ fProbintp[i]=0.;
+ fProbintn[i]=0.;
+ fPp[i]=0.;
+ }
}
//_____________________________________________________________________________
AliGenZDC::AliGenZDC(Int_t npart)
- :AliGenerator(npart)
+ :AliGenerator(npart),
+ fIpart(kNeutron),
+ fCosx(0.),
+ fCosy(0.),
+ fCosz(1.),
+ fPseudoRapidity(0.),
+ fFermiflag(1),
+ fBeamDiv(0.000032),
+ fBeamCrossAngle(0.0001),
+ fBeamCrossPlane(2),
+ fDebugOpt(0)
{
//
// 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++){
+ for(Int_t i=0; i<201; i++){
fProbintp[i] = 0;
fProbintn[i] = 0;
+ fPp[i] = 0;
}
- for(j=0; j<3; j++) fPp[i] = 0;
- fDebugOpt = 0;
}
//_____________________________________________________________________________
void AliGenZDC::Init()
{
+ //Initialize Fermi momentum distributions for Pb-Pb
+ //
printf("\n\n AliGenZDC initialization:\n");
printf(" Particle: %d, Track cosines: x = %f, y = %f, z = %f \n",
fIpart,fCosx,fCosy,fCosz);
"= %f, Crossing plane = %d\n\n", fFermiflag, fBeamDiv, fBeamCrossAngle,
fBeamCrossPlane);
- //Initialize Fermi momentum distributions for Pb-Pb
- FermiTwoGaussian(207.,fPp,fProbintp,fProbintn);
+ FermiTwoGaussian(208.);
}
//_____________________________________________________________________________
//
Int_t i;
- Double_t Mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3], dddp0, dddp[3];
+ Double_t mass, pLab[3], fP0, fP[3], fBoostP[3], ddp[3]={0.,0.,0.}, dddp0, dddp[3];
Float_t fPTrack[3], ptot = fPMin;
Int_t nt;
// Beam divergence and crossing angle
if(fBeamCrossAngle!=0.) {
- BeamDivCross(1,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
+ BeamDivCross(1, pLab);
for(i=0; i<=2; i++) fP[i] = pLab[i];
}
if(fBeamDiv!=0.) {
- BeamDivCross(0,fBeamDiv,fBeamCrossAngle,fBeamCrossPlane,pLab);
+ BeamDivCross(0, 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);
+ ExtractFermi(fIpart, ddp);
+ mass=TDatabasePDG::Instance()->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);
+ 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);
}
//_____________________________________________________________________________
-void AliGenZDC::FermiTwoGaussian(Float_t A, Double_t *fPp,
- Double_t *fProbintp, Double_t *fProbintn)
+void AliGenZDC::FermiTwoGaussian(Float_t A)
{
//
// 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));
}
}
//_____________________________________________________________________________
-void AliGenZDC::ExtractFermi(Int_t id, Double_t *fPp, Double_t *fProbintp,
- Double_t *fProbintn, Double_t *ddp)
+void AliGenZDC::ExtractFermi(Int_t id, Double_t *ddp)
{
//
// Compute Fermi momentum for spectator nucleons
//
- Int_t i;
+ Int_t index=0;
Float_t xx = gRandom->Rndm();
assert ( id==kProton || id==kNeutron );
if(id==kProton){
- for(i=1; i<=200; i++){
+ for(Int_t i=1; i<=200; i++){
if((xx>=fProbintp[i-1]) && (xx<fProbintp[i])) break;
- }
+ index = i;
+ }
}
else {
- for(i=0; i<=200; i++){
+ for(Int_t i=1; i<=200; i++){
if((xx>=fProbintn[i-1]) && (xx<fProbintn[i])) break;
- }
- }
- Float_t pext = fPp[i]+0.001;
- Float_t phi = k2PI*(gRandom->Rndm());
- 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;
+ index = i;
+ }
+ }
+ Float_t pext = fPp[index]+0.001;
+ Float_t phi = k2PI*(gRandom->Rndm());
+ 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");
}
//_____________________________________________________________________________
-void AliGenZDC::BeamDivCross(Int_t icross, Float_t fBeamDiv, Float_t fBeamCrossAngle,
- Int_t fBeamCrossPlane, Double_t *pLab)
+void AliGenZDC::BeamDivCross(Int_t icross, Double_t *pLab)
{
+ // Applying beam divergence and crossing angle
+ //
Double_t tetpart, fipart, tetdiv=0, fidiv=0, angleSum[2], tetsum, fisum;
Double_t rvec;
fidiv = (gRandom->Rndm())*k2PI;
}
else if(icross==1){ // ##### Crossing angle
- if(fBeamCrossPlane==0.){
+ if(fBeamCrossPlane==0){
tetdiv = 0.;
fidiv = 0.;
}
- else if(fBeamCrossPlane==1.){ // Horizontal crossing plane
+ else if(fBeamCrossPlane==1){ // Horizontal crossing plane
tetdiv = fBeamCrossAngle;
fidiv = 0.;
}
- else if(fBeamCrossPlane==2.){ // Vertical crossing plane
+ else if(fBeamCrossPlane==2){ // Vertical crossing plane
tetdiv = fBeamCrossAngle;
fidiv = k2PI/4.;
}
//_____________________________________________________________________________
void AliGenZDC::AddAngle(Double_t theta1, Double_t phi1, Double_t theta2,
Double_t phi2, Double_t *angleSum)
-{
+{
+ // Calculating the sum of 2 angles
Double_t temp, conv, cx, cy, cz, ct1, st1, ct2, st2, cp1, sp1, cp2, sp2;
Double_t rtetsum, tetsum, fisum;