newly implemented model for slow nucleon production

Chiara Oppedisano

diff --git a/EVGEN/AliGenSlowNucleons.cxx b/EVGEN/AliGenSlowNucleons.cxx
index 7b9a52b78507c476cb17a748120e798e2491e1e6..7bf44a4b29350620501fe676ffc0bf44a1379b74 100644 (file)
--- a/EVGEN/AliGenSlowNucleons.cxx
+++ b/EVGEN/AliGenSlowNucleons.cxx
@@ -140,7 +140,7 @@ void AliGenSlowNucleons::FinishRun()
        TCanvas *c = new TCanvas("c","Canvas 1",400,10,600,700);
        c->Divide(2,1);
        c->cd(1);
-       fDebugHist1->Draw();
+       fDebugHist1->Draw("colz");
        c->cd(2);
        fDebugHist2->Draw();
        c->cd(3);
@@ -164,11 +164,12 @@ void AliGenSlowNucleons::Generate()
        //      Int_t  nnw  = fCollisionGeometry->NNw();
        //      Int_t  nwnw = fCollisionGeometry->NwNw();
        
-       fSlowNucleonModel->GetNumberOfSlowNucleons(fCollisionGeometry, fNgp, fNgn, fNbp, fNbn);
+       //fSlowNucleonModel->GetNumberOfSlowNucleons(fCollisionGeometry, fNgp, fNgn, fNbp, fNbn);
+       fSlowNucleonModel->GetNumberOfSlowNucleons2(fCollisionGeometry, fNgp, fNgn, fNbp, fNbn);
        if (fDebug) {
            //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->NwN(), 1.);
+           fDebugHist1->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), fCollisionGeometry->NNw(), 1.);
            fDebugHist2->Fill(Float_t(fNgp + fNgn + fNbp + fNbn), b, 1.);
        }
     }     
@@ -195,7 +196,7 @@ void AliGenSlowNucleons::Generate()
        GenerateSlow(fCharge, fTemperatureG, fBetaSourceG, p, theta);
        if (fDebug) fCosThetaGrayHist->Fill(TMath::Cos(theta));
        PushTrack(fTrackIt, -1, kf, p, origin, polar,
-                time, kPNoProcess, nt, 1.,1);
+                time, kPNoProcess, nt, 1.,-2);
        KeepTrack(nt);
     }
 //
@@ -207,7 +208,7 @@ void AliGenSlowNucleons::Generate()
        GenerateSlow(fCharge, fTemperatureG, fBetaSourceG, p, theta);
        if (fDebug) fCosThetaGrayHist->Fill(TMath::Cos(theta));
        PushTrack(fTrackIt, -1, kf, p, origin, polar,
-                time, kPNoProcess, nt, 1.,1);
+                time, kPNoProcess, nt, 1.,-2);
        KeepTrack(nt);
     }
 //
@@ -218,7 +219,7 @@ void AliGenSlowNucleons::Generate()
     for(i = 0; i < fNbp; i++) {
        GenerateSlow(fCharge, fTemperatureB, fBetaSourceB, p, theta);
        PushTrack(fTrackIt, -1, kf, p, origin, polar,
-                time, kPNoProcess, nt, 1.,1);
+                time, kPNoProcess, nt, 1.,-1);
        KeepTrack(nt);
     }
 //
@@ -229,7 +230,7 @@ void AliGenSlowNucleons::Generate()
     for(i = 0; i < fNbn; i++) {
        GenerateSlow(fCharge, fTemperatureB, fBetaSourceB, p, theta);
        PushTrack(fTrackIt, -1, kf, p, origin, polar,
-                time, kPNoProcess, nt, 1.,1);
+                time, kPNoProcess, nt, 1.,-1);
        KeepTrack(nt);
     }
 }

diff --git a/EVGEN/AliSlowNucleonModel.h b/EVGEN/AliSlowNucleonModel.h
index 38b85a3cfc5bda525e5442f826b8737d965c2459..d78d7531ec929e35d6c79d0d3713c512fe57d538 100644 (file)
--- a/EVGEN/AliSlowNucleonModel.h
+++ b/EVGEN/AliSlowNucleonModel.h
@@ -16,6 +16,9 @@ public:
     virtual void GetNumberOfSlowNucleons(AliCollisionGeometry* /*geo*/,
                                         Int_t& /*ngp*/, Int_t& /*ngn*/,
                                         Int_t& /*nbp*/, Int_t& /*nbn*/) const {;}
+    virtual void GetNumberOfSlowNucleons2(AliCollisionGeometry* /*geo*/,
+                                        Int_t& /*ngp*/, Int_t& /*ngn*/,
+                                        Int_t& /*nbp*/, Int_t& /*nbn*/) const {;}
     
  protected:
   ClassDef(AliSlowNucleonModel,1) // Gray Particle Model

diff --git a/EVGEN/AliSlowNucleonModelExp.cxx b/EVGEN/AliSlowNucleonModelExp.cxx
index 9598cb2bf97d0543a3099c8714c90ec67a963dc0..5b73473d12266c3fbc1f1f95b78c6bff8a4e7e44 100644 (file)
--- a/EVGEN/AliSlowNucleonModelExp.cxx
+++ b/EVGEN/AliSlowNucleonModelExp.cxx
@@ -26,13 +26,14 @@
 #include "AliSlowNucleonModelExp.h"
 #include "AliCollisionGeometry.h"
 #include <TRandom.h>
+#include <TMath.h>
 
 ClassImp(AliSlowNucleonModelExp)
 
 
 AliSlowNucleonModelExp::AliSlowNucleonModelExp():
     fP(82),
-    fN (208 - 82),
+    fN (126),
     fAlphaGray(2.3),
     fAlphaBlack(3.6),
     fApplySaturation(kTRUE),
@@ -45,7 +46,7 @@ AliSlowNucleonModelExp::AliSlowNucleonModelExp():
   //
   printf("\n\nInitializing slow nucleon model with parameters:\n");
   printf(" \t alpha_{gray} %1.2f  alpha_{black} %1.2f\n",fAlphaGray, fAlphaBlack);
-  printf(" \t SATURATION %d w. %d (gray) %d (black) \n\n",fApplySaturation,fnGraySaturation,fnBlackSaturation);
+  //printf(" \t SATURATION %d w. %d (gray) %d (black) \n\n",fApplySaturation,fnGraySaturation,fnBlackSaturation);
 }
 
 
@@ -57,7 +58,7 @@ void AliSlowNucleonModelExp::GetNumberOfSlowNucleons(AliCollisionGeometry* geo,
 //
 // Number of collisions
 
-    Int_t nu = geo->NN() + geo->NwN() + geo->NNw(); 
+    Float_t nu = geo->NN() + geo->NwN() + geo->NNw(); 
 
 // Mean number of gray nucleons 
 
@@ -90,7 +91,79 @@ void AliSlowNucleonModelExp::GetNumberOfSlowNucleons(AliCollisionGeometry* geo,
 //  black protons
     p =  nBlackProtons/fP;
     nbp = gRandom->Binomial((Int_t) fP, p);
-       
+
+}
+
+void AliSlowNucleonModelExp::GetNumberOfSlowNucleons2(AliCollisionGeometry* geo, 
+                                                     Int_t& ngp, Int_t& ngn, Int_t & nbp, Int_t & nbn) const
+{
+//
+// Return the number of black and gray nucleons
+//
+// Number of collisions
+
+   // based on E910 model ================================================================
+
+   Float_t nu = (Float_t) (geo->NN() + geo->NwN() + geo->NNw()); 
+   //
+   nu = nu+1.*gRandom->Rndm();
+   //
+   Float_t  poverpd = 0.843; 
+   Float_t  zAu2zPb = 82./79.;
+   Float_t  nGrayp = (-0.27 + 0.63 * nu - 0.0008 *nu *nu)*poverpd*zAu2zPb;
+
+//  gray protons
+    Double_t p;
+    p =  nGrayp/fP;
+    ngp = gRandom->Binomial((Int_t) fP, p);
+    //ngp = gRandom->Gaus(nGrayp, TMath::Sqrt(fP*p*(1-p)));
+    if(nGrayp<0.) ngp=0;
+    
+    //Float_t blackovergray = 3./7.;// from spallation
+    Float_t blackovergray = 0.65; // from COSY
+    Float_t nBlackp  = blackovergray*nGrayp; 
+
+//  black protons
+    p =  nBlackp/fP;
+    nbp = gRandom->Binomial((Int_t) fP, p);
+    //nbp = gRandom->Gaus(nBlackp, TMath::Sqrt(fP*p*(1-p)));
+    if(nBlackp<0.) nbp=0;
+    
+    if(nu<3.){
+      nGrayp = -0.836 + 0.9112 *nu - 0.05381 *nu *nu;
+      nBlackp  = blackovergray*nGrayp; 
+    }
+    
+    Float_t nGrayNeutrons = 0.;
+    Float_t nBlackNeutrons = 0.;
+    Float_t cp = (nGrayp+nBlackp)/0.24;
+    
+    if(cp>0.){
+      Float_t nSlow  = 51.5+469.2/(-8.762-cp);
+      //if(cp<2.5) nSlow = 1+(9.9-1)/(2.5-0)*(cp-0);
+      if(cp<3.) nSlow = 0.+(11.6-0.)/(3.-0.)*(cp-0.);
+    
+      nGrayNeutrons = nSlow * 0.1; 
+      nBlackNeutrons = nSlow - nGrayNeutrons;
+    }
+    else{
+      // Sikler "pasturato"
+      nGrayNeutrons = 0.47 * fAlphaGray *  nu; 
+      nBlackNeutrons = 0.88 * fAlphaBlack * nu;      
+      printf("nslowp=0 -> ncoll = %1.0f -> ngrayn = %1.0f  nblackn = %1.0f \n", nu, nGrayNeutrons, nBlackNeutrons);
+    }
+    
+//  gray neutrons
+    p =  nGrayNeutrons/fN;
+//    ngn = gRandom->Binomial((Int_t) fN, p);
+    ngn = gRandom->Gaus(nGrayNeutrons, TMath::Sqrt(fN*p*(1-p)));
+
+//  black neutrons
+    p =  nBlackNeutrons/fN;
+//    nbn = gRandom->Binomial((Int_t) fN, p);
+    nbn = gRandom->Gaus(nBlackNeutrons, TMath::Sqrt(fN*p*(1-p)));
+    
+    
 }
 
 void AliSlowNucleonModelExp::SetParameters(Float_t alpha1, Float_t alpha2)

diff --git a/EVGEN/AliSlowNucleonModelExp.h b/EVGEN/AliSlowNucleonModelExp.h
index 83a240dfa64f99d5348f17f4f076c397885c830d..4755e44c4a79972f3cbc4b6f0e7b898fd05988ee 100644 (file)
--- a/EVGEN/AliSlowNucleonModelExp.h
+++ b/EVGEN/AliSlowNucleonModelExp.h
@@ -22,6 +22,8 @@ class AliSlowNucleonModelExp : public AliSlowNucleonModel
     virtual ~AliSlowNucleonModelExp(){;}
     virtual void GetNumberOfSlowNucleons(AliCollisionGeometry* geo,
                                         Int_t& ngp, Int_t& ngn, Int_t& nbp, Int_t& nbn) const;
+    virtual void GetNumberOfSlowNucleons2(AliCollisionGeometry* geo,
+                                        Int_t& ngp, Int_t& ngn, Int_t& nbp, Int_t& nbn) const;
     virtual void SetParameters(Float_t alpha1, Float_t alpha2);
     virtual void SetSaturation(Bool_t saturation) {fApplySaturation = saturation;}
     virtual void SetSaturationParams(Int_t ngray=15, Int_t nblack=28)