* provided "as is" without express or implied warranty. *
**************************************************************************/
-/*
-$Log$
-Revision 1.1 2003/03/24 16:49:23 morsch
-Slow nucleon generator and model.
+/* $Id$ */
-*/
-
-/*
- Generator for slow nucluons in pA interactions.
- Source is modelled by a relativistic Maxwell distributions.
- Original code by Ferenc Sikler <sikler@rmki.kfki.hu>
- */
+//
+// Generator for slow nucleons in pA interactions.
+// Source is modelled by a relativistic Maxwell distributions.
+// This class cooparates with AliCollisionGeometry if used inside AliGenCocktail.
+// In this case the number of slow nucleons is determined from the number of wounded nuclei
+// using a realisation of AliSlowNucleonModel.
+// Original code by Ferenc Sikler <sikler@rmki.kfki.hu>
+//
#include <TDatabasePDG.h>
#include <TPDGCode.h>
#include <TH2F.h>
+#include <TH1F.h>
+#include <TF1.h>
+#include <TCanvas.h>
+#include <TParticle.h>
+#include "AliConst.h"
#include "AliCollisionGeometry.h"
+#include "AliStack.h"
+#include "AliRun.h"
+#include "AliMC.h"
#include "AliGenSlowNucleons.h"
#include "AliSlowNucleonModel.h"
- ClassImp(AliGenSlowNucleons)
+ClassImp(AliGenSlowNucleons)
+
- AliGenSlowNucleons::AliGenSlowNucleons():AliGenerator(-1)
+AliGenSlowNucleons::AliGenSlowNucleons()
+ :AliGenerator(-1),
+ fCMS(0.),
+ fMomentum(0.),
+ fBeta(0.),
+ fPmax (0.),
+ fCharge(0),
+ fProtonDirection(1.),
+ fTemperatureG(0.),
+ fBetaSourceG(0.),
+ fTemperatureB(0.),
+ fBetaSourceB(0.),
+ fNgp(0),
+ fNgn(0),
+ fNbp(0),
+ fNbn(0),
+ fDebug(0),
+ fDebugHist1(0),
+ fDebugHist2(0),
+ fThetaDistribution(),
+ fCosThetaGrayHist(),
+ fCosTheta(),
+ fBeamCrossingAngle(0.),
+ fBeamDivergence(0.),
+ fBeamDivEvent(0.),
+ fSmearMode(2),
+ fSlowNucleonModel(0)
{
// Default constructor
- fSlowNucleonModel = 0;
fCollisionGeometry = 0;
}
AliGenSlowNucleons::AliGenSlowNucleons(Int_t npart)
- :AliGenerator(npart)
+ :AliGenerator(npart),
+ fCMS(14000.),
+ fMomentum(0.),
+ fBeta(0.),
+ fPmax (10.),
+ fCharge(1),
+ fProtonDirection(1.),
+ fTemperatureG(0.05),
+ fBetaSourceG(0.05),
+ fTemperatureB(0.005),
+ fBetaSourceB(0.),
+ fNgp(0),
+ fNgn(0),
+ fNbp(0),
+ fNbn(0),
+ fDebug(0),
+ fDebugHist1(0),
+ fDebugHist2(0),
+ fThetaDistribution(),
+ fCosThetaGrayHist(),
+ fCosTheta(),
+ fBeamCrossingAngle(0.),
+ fBeamDivergence(0.),
+ fBeamDivEvent(0.),
+ fSmearMode(2),
+ fSlowNucleonModel(new AliSlowNucleonModel())
+
{
// Constructor
fName = "SlowNucleons";
fTitle = "Generator for gray particles in pA collisions";
- SetPmax();
- SetTarget();
- SetNominalCmsEnergy();
- SetCharge();
- SetTemperature();
- SetBetaSource();
- fSlowNucleonModel = new AliSlowNucleonModel();
fCollisionGeometry = 0;
- fDebug = 0;
}
//____________________________________________________________
delete fSlowNucleonModel;
}
+void AliGenSlowNucleons::SetProtonDirection(Float_t dir) {
+// Set direction of the proton to change between pA (1) and Ap (-1)
+ fProtonDirection = dir / TMath::Abs(dir);
+}
void AliGenSlowNucleons::Init()
{
//
// Initialization
//
- Float_t kMass = TDatabasePDG::Instance()->GetParticle(kProton)->Mass();
- fMomentum = fCMS/2. * fZTarget / fATarget;
+ Double_t kMass = TDatabasePDG::Instance()->GetParticle(kProton)->Mass();
+ fMomentum = fCMS/2. * Float_t(fZTarget) / Float_t(fATarget);
fBeta = fMomentum / TMath::Sqrt(kMass * kMass + fMomentum * fMomentum);
+ //printf(" fMomentum %f fBeta %1.10f\n",fMomentum, fBeta);
if (fDebug) {
- fDebugHist = new TH2F("DebugHist", "N_heavy vs nu", 50, 0., 50., 50, 0., 50.);
+ fDebugHist1 = new TH2F("DebugHist1", "nu vs N_slow", 100, 0., 100., 20, 0., 20.);
+ fDebugHist2 = new TH2F("DebugHist2", "b vs N_slow", 100, 0., 100., 15, 0., 15.);
+ fCosThetaGrayHist = new TH1F("fCosThetaGrayHist", "Gray particles angle", 100, -1., 1.);
}
+ //
+ // non-uniform cos(theta) distribution
+ //
+ if(fThetaDistribution != 0) {
+ fCosTheta = new TF1("fCosTheta",
+ "(2./3.14159265358979312)/(exp(2./3.14159265358979312)-exp(-2./3.14159265358979312))*exp(2.*x/3.14159265358979312)",
+ -1., 1.);
+ }
+
+ printf("\n AliGenSlowNucleons: applying crossing angle %f mrad to slow nucleons\n",fBeamCrossingAngle*1000.);
}
void AliGenSlowNucleons::FinishRun()
{
+// End of run action
+// Show histogram for debugging if requested.
if (fDebug) {
- fDebugHist->Draw();
+ TCanvas *c = new TCanvas("c","Canvas 1",400,10,600,700);
+ c->Divide(2,1);
+ c->cd(1);
+ fDebugHist1->Draw("colz");
+ c->cd(2);
+ fDebugHist2->Draw();
+ c->cd(3);
+ fCosThetaGrayHist->Draw();
}
}
//
// Communication with Gray Particle Model
//
- Int_t ngp, ngn, nbp, nbn;
-
if (fCollisionGeometry) {
Float_t b = fCollisionGeometry->ImpactParameter();
- Int_t nn = fCollisionGeometry->NN();
- Int_t nwn = fCollisionGeometry->NwN();
- Int_t nnw = fCollisionGeometry->NNw();
- Int_t nwnw = fCollisionGeometry->NwNw();
-
- fSlowNucleonModel->GetNumberOfSlowNucleons(fCollisionGeometry, ngp, ngn, nbp, nbn);
+ // Int_t nn = fCollisionGeometry->NN();
+ // Int_t nwn = fCollisionGeometry->NwN();
+ // Int_t nnw = fCollisionGeometry->NNw();
+ // Int_t nwnw = fCollisionGeometry->NwNw();
+
+ // (1) Sikler' model
+ if(fSmearMode==0) fSlowNucleonModel->GetNumberOfSlowNucleons(fCollisionGeometry, fNgp, fNgn, fNbp, fNbn);
+ // (2) Model inspired on exp. data at lower energy (Gallio-Oppedisano)
+ // --- smearing the Ncoll fron generator used as input
+ else if(fSmearMode==1) fSlowNucleonModel->GetNumberOfSlowNucleons2(fCollisionGeometry, fNgp, fNgn, fNbp, fNbn);
+ // --- smearing directly Nslow
+ else if(fSmearMode==2) fSlowNucleonModel->GetNumberOfSlowNucleons2s(fCollisionGeometry, fNgp, fNgn, fNbp, fNbn);
if (fDebug) {
- printf("Nucleons %d %d %d %d \n", fNgp, fNgn, fNbp, fNbn);
- fDebugHist->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), fCollisionGeometry->NwN(), 1.);
- printf("AliGenSlowNucleons: Impact parameter from Collision Geometry %f %d %d %d %d\n",
- b, nn, nwn, nnw, nwnw);
+ //printf("Collision Geometry %f %d %d %d %d\n", b, nn, nwn, nnw, nwnw);
+ printf("Slow nucleons: %d grayp %d grayn %d blackp %d blackn \n", fNgp, fNgn, fNbp, fNbn);
+ fDebugHist1->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), fCollisionGeometry->NNw(), 1.);
+ fDebugHist2->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), b, 1.);
+
}
}
//
- Float_t p[3];
+ Float_t p[3] = {0., 0., 0.}, theta=0;
Float_t origin[3] = {0., 0., 0.};
+ Float_t time = 0.;
Float_t polar [3] = {0., 0., 0.};
- Int_t nt, i;
+ Int_t nt, i, j;
Int_t kf;
+
+ // Extracting 1 value per event for the divergence angle
+ Double_t rvec = gRandom->Gaus(0.0, 1.0);
+ fBeamDivEvent = fBeamDivergence * TMath::Abs(rvec);
+ printf("\n AliGenSlowNucleons: applying beam divergence %f mrad to slow nucleons\n",fBeamDivEvent*1000.);
+
+ if(fVertexSmear == kPerEvent) {
+ Vertex();
+ for (j=0; j < 3; j++) origin[j] = fVertex[j];
+ time = fTime;
+ } // if kPerEvent
//
// Gray protons
//
fCharge = 1;
kf = kProton;
for(i = 0; i < fNgp; i++) {
- GenerateSlow(fCharge, fTemperatureG, fBetaSourceG, p);
- SetTrack(fTrackIt, -1, kf, p, origin, polar,
- 0., kPNoProcess, nt, 1.);
+ GenerateSlow(fCharge, fTemperatureG, fBetaSourceG, p, theta);
+ if (fDebug) fCosThetaGrayHist->Fill(TMath::Cos(theta));
+ PushTrack(fTrackIt, -1, kf, p, origin, polar,
+ time, kPNoProcess, nt, 1.,-2);
KeepTrack(nt);
+ SetProcessID(nt,kGrayProcess);
}
//
// Gray neutrons
fCharge = 0;
kf = kNeutron;
for(i = 0; i < fNgn; i++) {
- GenerateSlow(fCharge, fTemperatureG, fBetaSourceG, p);
- SetTrack(fTrackIt, -1, kf, p, origin, polar,
- 0., kPNoProcess, nt, 1.);
+ GenerateSlow(fCharge, fTemperatureG, fBetaSourceG, p, theta);
+ if (fDebug) fCosThetaGrayHist->Fill(TMath::Cos(theta));
+ PushTrack(fTrackIt, -1, kf, p, origin, polar,
+ time, kPNoProcess, nt, 1.,-2);
KeepTrack(nt);
+ SetProcessID(nt,kGrayProcess);
}
//
// Black protons
fCharge = 1;
kf = kProton;
for(i = 0; i < fNbp; i++) {
- GenerateSlow(fCharge, fTemperatureB, fBetaSourceB, p);
- SetTrack(fTrackIt, -1, kf, p, origin, polar,
- 0., kPNoProcess, nt, 1.);
+ GenerateSlow(fCharge, fTemperatureB, fBetaSourceB, p, theta);
+ PushTrack(fTrackIt, -1, kf, p, origin, polar,
+ time, kPNoProcess, nt, 1.,-1);
KeepTrack(nt);
+ SetProcessID(nt,kBlackProcess);
}
//
// Black neutrons
fCharge = 0;
kf = kNeutron;
for(i = 0; i < fNbn; i++) {
- GenerateSlow(fCharge, fTemperatureB, fBetaSourceB, p);
- SetTrack(fTrackIt, -1, kf, p, origin, polar,
- 0., kPNoProcess, nt, 1.);
+ GenerateSlow(fCharge, fTemperatureB, fBetaSourceB, p, theta);
+ PushTrack(fTrackIt, -1, kf, p, origin, polar,
+ time, kPNoProcess, nt, 1.,-1);
KeepTrack(nt);
+ SetProcessID(nt,kBlackProcess);
}
}
-void AliGenSlowNucleons::GenerateSlow(Int_t charge, Double_t T, Double_t beta, Float_t* q)
+void AliGenSlowNucleons::GenerateSlow(Int_t charge, Double_t T,
+ Double_t beta, Float_t* q, Float_t &theta)
+
+{
/*
Emit a slow nucleon with "temperature" T [GeV],
from a source moving with velocity beta
Three-momentum [GeV/c] is given back in q[3]
*/
-{
- Double_t m, pmax, p, f, theta, phi;
+ //printf("Generating slow nuc. with: charge %d. temp. %1.4f, beta %f \n",charge,T,beta);
+ Double_t m, pmax, p, f, phi;
TDatabasePDG * pdg = TDatabasePDG::Instance();
const Double_t kMassProton = pdg->GetParticle(kProton) ->Mass();
const Double_t kMassNeutron = pdg->GetParticle(kNeutron)->Mass();
/* Momentum at maximum of Maxwell-distribution */
- pmax = TMath::Sqrt(2*T*(T+sqrt(T*T+m*m)));
+ pmax = TMath::Sqrt(2*T*(T+TMath::Sqrt(T*T+m*m)));
/* Try until proper momentum */
/* for lack of primitive function of the Maxwell-distribution */
}
while(f < Rndm());
- /* Spherical symmetric emission */
- theta = TMath::ACos(2. * Rndm() - 1.);
+ /* Spherical symmetric emission for black particles (beta=0)*/
+ if(beta==0 || fThetaDistribution==0) theta = TMath::ACos(2. * Rndm() - 1.);
+ /* cos theta distributed according to experimental results for gray particles (beta=0.05)*/
+ else if(fThetaDistribution!=0){
+ Double_t costheta = fCosTheta->GetRandom();
+ theta = TMath::ACos(costheta);
+ }
+ //
phi = 2. * TMath::Pi() * Rndm();
+
/* Determine momentum components in system of the moving source */
q[0] = p * TMath::Sin(theta) * TMath::Cos(phi);
q[1] = p * TMath::Sin(theta) * TMath::Sin(phi);
q[2] = p * TMath::Cos(theta);
+ //if(fDebug==1) printf("\n Momentum in RS of the moving source: p = (%f, %f, %f)\n",q[0],q[1],q[2]);
+
/* Transform to system of the target nucleus */
/* beta is passed as negative, because the gray nucleons are slowed down */
Lorentz(m, -beta, q);
+ //if(fDebug==1) printf(" Momentum in RS of the target nucleus: p = (%f, %f, %f)\n",q[0],q[1],q[2]);
/* Transform to laboratory system */
Lorentz(m, fBeta, q);
+ q[2] *= fProtonDirection;
+ if(fDebug==1)printf("\n Momentum after LHC boost: p = (%f, %f, %f)\n",q[0],q[1],q[2]);
+
+ if(fBeamCrossingAngle>0.) BeamCrossDivergence(1, q); // applying crossing angle
+ if(fBeamDivergence>0.) BeamCrossDivergence(2, q); // applying divergence
+
}
Double_t AliGenSlowNucleons::Maxwell(Double_t m, Double_t p, Double_t T)
}
+//_____________________________________________________________________________
void AliGenSlowNucleons::Lorentz(Double_t m, Double_t beta, Float_t* q)
{
/* Lorentz transform in the direction of q[2] */
- Double_t gamma = 1/sqrt(1-beta*beta);
- Double_t energy = sqrt(m*m + q[0]*q[0] + q[1]*q[1] + q[2]*q[2]);
+ Double_t gamma = 1./TMath::Sqrt((1.-beta)*(1.+beta));
+ Double_t energy = TMath::Sqrt(m*m + q[0]*q[0] + q[1]*q[1] + q[2]*q[2]);
q[2] = gamma * (q[2] + beta*energy);
+ //printf(" \t beta %1.10f gamma %f energy %f -> p_z = %f\n",beta, gamma, energy,q[2]);
}
-
-
-
-
-
-
+//_____________________________________________________________________________
+void AliGenSlowNucleons::BeamCrossDivergence(Int_t iwhat, Float_t *pLab)
+{
+ // Applying beam divergence and crossing angle
+ //
+ Double_t pmod = TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1]+pLab[2]*pLab[2]);
+
+ Double_t tetdiv = 0.;
+ Double_t fidiv = 0.;
+ if(iwhat==1){
+ tetdiv = fBeamCrossingAngle;
+ fidiv = k2PI/4.;
+ }
+ else if(iwhat==2){
+ tetdiv = fBeamDivEvent;
+ fidiv = (gRandom->Rndm())*k2PI;
+ }
+
+ Double_t tetpart = TMath::ATan2(TMath::Sqrt(pLab[0]*pLab[0]+pLab[1]*pLab[1]), pLab[2]);
+ Double_t fipart=0.;
+ if(TMath::Abs(pLab[1])>0. || TMath::Abs(pLab[0])>0.) fipart = TMath::ATan2(pLab[1], pLab[0]);
+ if(fipart<0.) {fipart = fipart+k2PI;}
+ tetdiv = tetdiv*kRaddeg;
+ fidiv = fidiv*kRaddeg;
+ tetpart = tetpart*kRaddeg;
+ fipart = fipart*kRaddeg;
+
+ Double_t angleSum[2]={0., 0.};
+ AddAngle(tetpart,fipart,tetdiv,fidiv,angleSum);
+
+ Double_t tetsum = angleSum[0];
+ Double_t fisum = angleSum[1];
+ //printf("tetpart %f fipart %f tetdiv %f fidiv %f angleSum %f %f\n",tetpart,fipart,tetdiv,fidiv,angleSum[0],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(fDebug==1){
+ if(iwhat==1) printf(" Beam crossing angle %f mrad ", fBeamCrossingAngle*1000.);
+ else if(iwhat==2) printf(" Beam divergence %f mrad ", fBeamDivEvent*1000.);
+ printf(" p = (%f, %f, %f)\n",pLab[0],pLab[1],pLab[2]);
+ }
+}
+
+//_____________________________________________________________________________
+void AliGenSlowNucleons::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 = -1.;
+ Double_t conv = 180./TMath::ACos(temp);
+
+ Double_t ct1 = TMath::Cos(theta1/conv);
+ Double_t st1 = TMath::Sin(theta1/conv);
+ Double_t cp1 = TMath::Cos(phi1/conv);
+ Double_t sp1 = TMath::Sin(phi1/conv);
+ Double_t ct2 = TMath::Cos(theta2/conv);
+ Double_t st2 = TMath::Sin(theta2/conv);
+ Double_t cp2 = TMath::Cos(phi2/conv);
+ Double_t sp2 = TMath::Sin(phi2/conv);
+ Double_t cx = ct1*cp1*st2*cp2+st1*cp1*ct2-sp1*st2*sp2;
+ Double_t cy = ct1*sp1*st2*cp2+st1*sp1*ct2+cp1*st2*sp2;
+ Double_t cz = ct1*ct2-st1*st2*cp2;
+
+ Double_t rtetsum = TMath::ACos(cz);
+ Double_t tetsum = conv*rtetsum;
+ if(TMath::Abs(tetsum)<1e-4 || tetsum==180.) return;
+
+ temp = cx/TMath::Sin(rtetsum);
+ if(temp>1.) temp=1.;
+ if(temp<-1.) temp=-1.;
+ Double_t fisum = conv*TMath::ACos(temp);
+ if(cy<0) {fisum = 360.-fisum;}
+
+ angleSum[0] = tetsum;
+ angleSum[1] = fisum;
+}
+
+//_____________________________________________________________________________
+void AliGenSlowNucleons::SetProcessID(Int_t nt, UInt_t process)
+{
+ // Tag the particle as
+ // gray or black
+ if (fStack)
+ fStack->Particle(nt)->SetUniqueID(process);
+ else
+ gAlice->GetMCApp()->Particle(nt)->SetUniqueID(process);
+}
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