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25 //
26 //
27 //
28 // Hadronic Process: Nuclear De-excitations
29 // by V. Lara (Oct 1998)
30 //
31 //
32 // J.M.Quesada (14 february 2009) bug fixed in fission width: missing
33 // parenthesis in the denominator
34
35
36 #include "G4FissionProbability.hh"
37 #include "G4PhysicalConstants.hh"
38 #include "G4NuclearLevelData.hh"
39 #include "G4PairingCorrection.hh"
40 #include "G4EvaporationLevelDensityParameter.hh"
41 #include "G4FissionLevelDensityParameter.hh"
42 #include "G4Exp.hh"
43
44 G4FissionProbability::G4FissionProbability() :
45 G4VEmissionProbability(0, 0),
46 theEvapLDP(new G4EvaporationLevelDensityParameter),
47 theFissLDP(new G4FissionLevelDensityParameter),
48 ownEvapLDP(true),
49 ownFissLDP(true)
50 {
51 fPairCorr = G4NuclearLevelData::GetInstance()->GetPairingCorrection();
52 }
53
54 G4FissionProbability::~G4FissionProbability()
55 {
56 if (ownEvapLDP) delete theEvapLDP;
57 if (ownFissLDP) delete theFissLDP;
58 }
59
60 G4double
61 G4FissionProbability::EmissionProbability(const G4Fragment & fragment,
62 G4double MaximalKineticEnergy)
63 // Compute integrated probability of fission channel
64 {
65 if (MaximalKineticEnergy <= 0.0) { return 0.0; }
66 G4int A = fragment.GetA_asInt();
67 G4int Z = fragment.GetZ_asInt();
68 G4double U = fragment.GetExcitationEnergy();
69
70 G4double Ucompound = U - fPairCorr->GetPairingCorrection(A,Z);
71 G4double Ufission = U - fPairCorr->GetFissionPairingCorrection(A,Z);
72 if(Ucompound < 0.0 || Ufission < 0.0) { return 0.0; }
73
74 G4double SystemEntropy =
75 2.0*std::sqrt(theEvapLDP->LevelDensityParameter(A,Z,Ucompound)*Ucompound);
76
77 G4double afission = theFissLDP->LevelDensityParameter(A,Z,Ufission);
78
79 G4double Cf = 2.0*std::sqrt(afission*MaximalKineticEnergy);
80 G4double Exp1 = (SystemEntropy <= 160.0) ? G4Exp(-SystemEntropy) : 0.0;
81 G4double Exp2 = (SystemEntropy-Cf <= 160.0) ? G4Exp(-SystemEntropy+Cf) : 0.0;
82
83 // JMQ 14/02/09 BUG fixed in fission probability (missing parenthesis
84 // at denominator)
85 G4double probability = (Exp1 + (Cf-1.0)*Exp2) / (4.0*pi*afission);
86
87 return probability;
88 }
89
90