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19 // Experimental data inspired Gray Particle Model for p-Pb collisions
20 // The number of gray nucleons is proportional to the number of collisions.
21 // The number of black nucleons is proportional to the number of collisions
22 // Fluctuations are calculated from a binomial distribution.
26 #include "AliSlowNucleonModelExp.h"
27 #include "AliCollisionGeometry.h"
30 ClassImp(AliSlowNucleonModelExp)
33 AliSlowNucleonModelExp::AliSlowNucleonModelExp():
38 fApplySaturation(kTRUE),
43 // Default constructor
48 void AliSlowNucleonModelExp::GetNumberOfSlowNucleons(AliCollisionGeometry* geo,
49 Int_t& ngp, Int_t& ngn, Int_t & nbp, Int_t & nbn) const
52 // Return the number of black and gray nucleons
54 // Number of collisions
56 Int_t nu = geo->NwN() + geo->NNw();
58 // Mean number of gray nucleons
60 Float_t nGray = fAlphaGray * nu;
61 Float_t nGrayNeutrons = nGray * fN / (fN + fP);
62 Float_t nGrayProtons = nGray - nGrayNeutrons;
64 // Mean number of black nucleons
66 if(!fApplySaturation || (fApplySaturation && nGray<fnGraySaturation)) nBlack = fAlphaBlack * nu;
67 else if(fApplySaturation && nGray>=fnGraySaturation) nBlack = fnBlackSaturation;
68 Float_t nBlackNeutrons = nBlack * fN / (fN + fP);
69 Float_t nBlackProtons = nBlack - nBlackNeutrons;
71 // Actual number (including fluctuations) from binomial distribution
76 ngn = gRandom->Binomial((Int_t) fN, p);
80 ngp = gRandom->Binomial((Int_t) fP, p);
83 p = nBlackNeutrons/fN;
84 nbn = gRandom->Binomial((Int_t) fN, p);
88 nbp = gRandom->Binomial((Int_t) fP, p);
92 void AliSlowNucleonModelExp::SetParameters(Float_t alpha1, Float_t alpha2)
94 // Set the model parameters