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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)
32 AliSlowNucleonModelExp::AliSlowNucleonModelExp()
35 // Default constructor
44 void AliSlowNucleonModelExp::GetNumberOfSlowNucleons(AliCollisionGeometry* geo,
45 Int_t& ngp, Int_t& ngn, Int_t & nbp, Int_t & nbn) const
48 // Return the number of black and gray nucleons
50 // Number of collisions
52 Int_t nu = geo->NwN() + geo->NNw();
54 // Mean number of gray nucleons
56 Float_t nGray = fAlphaGray * nu;
57 Float_t nGrayNeutrons = nGray * fN / (fN + fP);
58 Float_t nGrayProtons = nGray - nGrayNeutrons;
60 // Mean number of black nucleons
61 Float_t nBlack = fAlphaBlack * nu;
62 Float_t nBlackNeutrons = nBlack * fN / (fN + fP);
63 Float_t nBlackProtons = nBlack - nBlackNeutrons;
65 // Actual number (including fluctuations) from binomial distribution
70 ngn = gRandom->Binomial((Int_t) fN, p);
74 ngp = gRandom->Binomial((Int_t) fP, p);
77 p = nBlackNeutrons/fN;
78 nbn = gRandom->Binomial((Int_t) fN, p);
82 nbp = gRandom->Binomial((Int_t) fP, p);
86 void AliSlowNucleonModelExp::SetParameters(Float_t alpha1, Float_t alpha2)
88 // Set the model parameters