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26 //
27 // -------------------------------------------------------------------
28 // GEANT 4 class implementation file
29 //
30 // CERN, Geneva, Switzerland
31 //
32 // File name: G4AntiProtonField.cc
33 //
34 // Author: Alessandro Brunengo (Alessandro.Brunengo@ge.infn.it)
35 //
36 // Creation date: 5 June 2000
37 // -------------------------------------------------------------------
38
39 #include "G4AntiProtonField.hh"
40 #include "G4PhysicalConstants.hh"
41 #include "G4SystemOfUnits.hh"
42 #include "G4NucleiProperties.hh"
43 #include "G4VNuclearDensity.hh"
44 #include "G4FermiMomentum.hh"
45 #include "G4ParticleDefinition.hh"
46 #include "G4AntiProton.hh"
47 #include "G4HadTmpUtil.hh"
48 #include "G4Pow.hh"
49
50 G4AntiProtonField::G4AntiProtonField(G4V3DNucleus * nucleus, G4double coeff)
51 : G4VNuclearField(nucleus)
52 {
53 theCoeff = coeff;
54 }
55
56
57 G4AntiProtonField::~G4AntiProtonField()
58 { }
59
60
61
62
63 G4double G4AntiProtonField::GetField(const G4ThreeVector & aPosition)
64 {
65 // Field is 0 out of the nucleus!
66 if(aPosition.mag() >= radius) return 0.0;
67
68 const G4ParticleDefinition *anAntiProton = G4AntiProton::AntiProtonDefinition();
69 G4double antiProtonMass = anAntiProton->GetPDGMass();
70
71 G4int A = theNucleus->GetMassNumber();
72 G4int Z = theNucleus->GetCharge();
73 G4double bindingEnergy = G4NucleiProperties::GetBindingEnergy(A, Z);
74 G4double nucleusMass = Z*proton_mass_c2+(A-Z)*neutron_mass_c2+bindingEnergy;
75 G4double reducedMass = antiProtonMass*nucleusMass/(antiProtonMass+nucleusMass);
76
77 G4double density = theNucleus->GetNuclearDensity()->GetDensity(aPosition);
78
79 return -2.*pi*hbarc*hbarc/reducedMass*(2.0)*theCoeff*density+GetBarrier();
80 }
81
82
83 G4double G4AntiProtonField::GetBarrier()
84 {
85 G4int A = theNucleus->GetMassNumber();
86 G4int Z = theNucleus->GetCharge();
87 G4double coulombBarrier = (1.44/1.14) * MeV * Z / (1.0 + G4Pow::GetInstance()->Z13(A));
88 return -coulombBarrier;
89 }
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