| Geant4 Cross Reference |
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25 // 25 //
26 // 26 //
27 // Abstract base class for multibody "phase sp 27 // Abstract base class for multibody "phase space" generators. Subclasses
28 // implement a specific algorithm, such as Kop 28 // implement a specific algorithm, such as Kopylov, GENBOD, or Makoto's
29 // NBody. Subclasses are used by G4HadPhaseSp 29 // NBody. Subclasses are used by G4HadPhaseSpaceGenerator.
30 // 30 //
31 // Author: Michael Kelsey (SLAC) <kelsey@slac 31 // Author: Michael Kelsey (SLAC) <kelsey@slac.stanford.edu>
32 32
33 #include "G4VHadDecayAlgorithm.hh" 33 #include "G4VHadDecayAlgorithm.hh"
34 #include "G4HadronicException.hh" 34 #include "G4HadronicException.hh"
35 #include "G4PhysicalConstants.hh" 35 #include "G4PhysicalConstants.hh"
36 #include "G4SystemOfUnits.hh" 36 #include "G4SystemOfUnits.hh"
37 #include "G4ThreeVector.hh" 37 #include "G4ThreeVector.hh"
38 #include "Randomize.hh" 38 #include "Randomize.hh"
39 #include <algorithm> 39 #include <algorithm>
40 #include <iostream> 40 #include <iostream>
41 #include <iterator> 41 #include <iterator>
42 #include <numeric> 42 #include <numeric>
43 #include <vector> 43 #include <vector>
44 44
45 45
46 // Initial state (rest mass) and list of final 46 // Initial state (rest mass) and list of final masses
47 47
48 void G4VHadDecayAlgorithm::Generate(G4double i 48 void G4VHadDecayAlgorithm::Generate(G4double initialMass,
49 const std::vector<G4double>& masse 49 const std::vector<G4double>& masses,
50 std::vector<G4LorentzVector>& fina 50 std::vector<G4LorentzVector>& finalState) {
51 if (verboseLevel) G4cout << GetName() << ":: 51 if (verboseLevel) G4cout << GetName() << "::Generate" << G4endl;
52 52
53 // Initialization and sanity check 53 // Initialization and sanity check
54 finalState.clear(); 54 finalState.clear();
55 if (!IsDecayAllowed(initialMass, masses)) re 55 if (!IsDecayAllowed(initialMass, masses)) return;
56 56
57 // Allow different procedures for two-body o 57 // Allow different procedures for two-body or N-body distributions
58 if (masses.size() == 2U) 58 if (masses.size() == 2U)
59 GenerateTwoBody(initialMass, masses, final 59 GenerateTwoBody(initialMass, masses, finalState);
60 else 60 else
61 GenerateMultiBody(initialMass, masses, fin 61 GenerateMultiBody(initialMass, masses, finalState);
62 } 62 }
63 63
64 64
65 // Base class does very simple validation of c 65 // Base class does very simple validation of configuration
66 66
67 G4bool G4VHadDecayAlgorithm:: 67 G4bool G4VHadDecayAlgorithm::
68 IsDecayAllowed(G4double initialMass, 68 IsDecayAllowed(G4double initialMass,
69 const std::vector<G4double>& masses) 69 const std::vector<G4double>& masses) const {
70 G4bool okay = 70 G4bool okay =
71 (initialMass > 0. && masses.size() >= 2 && 71 (initialMass > 0. && masses.size() >= 2 &&
72 initialMass >= std::accumulate(masses.beg 72 initialMass >= std::accumulate(masses.begin(),masses.end(),0.));
73 73
74 if (verboseLevel) { 74 if (verboseLevel) {
75 G4cout << GetName() << "::IsDecayAllowed? 75 G4cout << GetName() << "::IsDecayAllowed? initialMass " << initialMass
76 << " " << masses.size() << " masses sum " 76 << " " << masses.size() << " masses sum "
77 << std::accumulate(masses.begin(),masses. 77 << std::accumulate(masses.begin(),masses.end(),0.) << G4endl;
78 78
79 if (verboseLevel>1) PrintVector(masses," " 79 if (verboseLevel>1) PrintVector(masses," ",G4cout);
80 80
81 G4cout << " Returning " << okay << G4endl; 81 G4cout << " Returning " << okay << G4endl;
82 } 82 }
83 83
84 return okay; 84 return okay;
85 } 85 }
86 86
87 87
88 // Momentum function (c.f. PDK() function from 88 // Momentum function (c.f. PDK() function from CERNLIB W515)
89 89
90 G4double G4VHadDecayAlgorithm::TwoBodyMomentum 90 G4double G4VHadDecayAlgorithm::TwoBodyMomentum(G4double M0, G4double M1,
91 G4double M2) const { 91 G4double M2) const {
92 G4double PSQ = (M0+M1+M2)*(M0+M1-M2)*(M0-M1+ 92 G4double PSQ = (M0+M1+M2)*(M0+M1-M2)*(M0-M1+M2)*(M0-M1-M2);
93 if (PSQ < 0.) { 93 if (PSQ < 0.) {
94 G4cout << GetName() << ": problem of deca 94 G4cout << GetName() << ": problem of decay of M(GeV) " << M0/GeV
95 << " to M1(GeV) " << M1/GeV << " and M2(G 95 << " to M1(GeV) " << M1/GeV << " and M2(GeV) " << M2/GeV
96 << " PSQ(MeV) " << PSQ/MeV << " < 0" << G 96 << " PSQ(MeV) " << PSQ/MeV << " < 0" << G4endl;
97 // exception only if the problem is numeri 97 // exception only if the problem is numerically significant
98 if (PSQ < -CLHEP::eV) { 98 if (PSQ < -CLHEP::eV) {
99 throw G4HadronicException(__FILE__, __LI 99 throw G4HadronicException(__FILE__, __LINE__,"Error in decay kinematics");
100 } 100 }
101 101
102 PSQ = 0.; 102 PSQ = 0.;
103 } 103 }
104 104
105 return std::sqrt(PSQ)/(2.*M0); 105 return std::sqrt(PSQ)/(2.*M0);
106 } 106 }
107 107
108 // Convenience functions for uniform angular d 108 // Convenience functions for uniform angular distributions
109 109
110 G4double G4VHadDecayAlgorithm::UniformTheta() 110 G4double G4VHadDecayAlgorithm::UniformTheta() const {
111 return std::acos(2.0*G4UniformRand() - 1.0); 111 return std::acos(2.0*G4UniformRand() - 1.0);
112 } 112 }
113 113
114 G4double G4VHadDecayAlgorithm::UniformPhi() co 114 G4double G4VHadDecayAlgorithm::UniformPhi() const {
115 return twopi*G4UniformRand(); 115 return twopi*G4UniformRand();
116 } 116 }
117 117
118 118
119 // Dump contents of vector to output 119 // Dump contents of vector to output
120 120
121 void G4VHadDecayAlgorithm:: 121 void G4VHadDecayAlgorithm::
122 PrintVector(const std::vector<G4double>& v, 122 PrintVector(const std::vector<G4double>& v,
123 const G4String& vname, std::ostream& os) 123 const G4String& vname, std::ostream& os) const {
124 os << " " << vname << "(" << v.size() << ") 124 os << " " << vname << "(" << v.size() << ") ";
125 std::copy(v.begin(), v.end(), std::ostream_i 125 std::copy(v.begin(), v.end(), std::ostream_iterator<G4double>(os, " "));
126 os << std::endl; 126 os << std::endl;
127 } 127 }
128 128