* 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 "AliCollisionGeometry.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.),
+ fATarget (0.),
+ fZTarget (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(),
+ 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.),
+ fATarget (208.),
+ fZTarget (82.),
+ fCharge(1),
+ fProtonDirection(1.),
+ fTemperatureG(0.04),
+ fBetaSourceG(0.05),
+ fTemperatureB(0.004),
+ fBetaSourceB(0.),
+ fNgp(0),
+ fNgn(0),
+ fNbp(0),
+ fNbn(0),
+ fDebug(0),
+ fDebugHist1(0),
+ fDebugHist2(0),
+ fThetaDistribution(),
+ fCosThetaGrayHist(),
+ fCosTheta(),
+ 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()
{
fMomentum = fCMS/2. * fZTarget / fATarget;
fBeta = fMomentum / TMath::Sqrt(kMass * kMass + fMomentum * fMomentum);
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.);
}
}
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();
+ 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 nnw = fCollisionGeometry->NNw();
Int_t nwnw = fCollisionGeometry->NwNw();
- fSlowNucleonModel->GetNumberOfSlowNucleons(fCollisionGeometry, ngp, ngn, nbp, nbn);
+ fSlowNucleonModel->GetNumberOfSlowNucleons(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.);
+ fDebugHist1->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), fCollisionGeometry->NwN(), 1.);
+ fDebugHist2->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), b, 1.);
printf("AliGenSlowNucleons: Impact parameter from Collision Geometry %f %d %d %d %d\n",
b, nn, nwn, nnw, nwnw);
}
}
//
- Float_t p[3];
+ Float_t p[3], 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;
+
+ 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.);
KeepTrack(nt);
}
//
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.);
KeepTrack(nt);
}
//
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.);
KeepTrack(nt);
}
//
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.);
KeepTrack(nt);
}
}
-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;
-
+ 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();
}
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 */
/* Transform to laboratory system */
Lorentz(m, fBeta, q);
+ q[2] *= fProtonDirection;
}
Double_t AliGenSlowNucleons::Maxwell(Double_t m, Double_t p, Double_t T)
{
/* Lorentz transform in the direction of q[2] */
- Double_t gamma = 1/sqrt(1-beta*beta);
+ Double_t gamma = 1./sqrt((1.-beta)*(1.+beta));
Double_t energy = sqrt(m*m + q[0]*q[0] + q[1]*q[1] + q[2]*q[2]);
q[2] = gamma * (q[2] + beta*energy);
}
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git://git.uio.no / u / mrichter / AliRoot.git / blobdiff