Geant4  10.01
G4SampleResonance.cc
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28 // ------------------------------------------------------------
29 // GEANT 4 class header file
30 //
31 // ---------------- G4SampleResonance ----------------
32 // by Henning Weber, March 2001.
33 // helper class for sampling resonance masses
34 // ------------------------------------------------------------
35 
36 
37 #include "globals.hh"
38 #include <iostream>
39 #include "G4SampleResonance.hh"
40 #include "G4DecayTable.hh"
41 #include "Randomize.hh"
42 #include "G4HadronicException.hh"
43 
45 
48 
49  G4double minResonanceMass = DBL_MAX;
50 
51  if ( p->IsShortLived() )
52  {
53  minMassMapIterator iter = minMassCache.find(p);
54  if ( iter!=minMassCache.end() )
55  {
56  minResonanceMass = (*iter).second;
57  }
58  else
59  {
60  // G4cout << "--> request for " << p->GetParticleName() << G4endl;
61 
62  const G4DecayTable* theDecays = p->GetDecayTable();
63  const G4int nDecays = theDecays->entries();
64 
65  for (G4int i=0; i<nDecays; i++)
66  {
67  const G4VDecayChannel* aDecay = theDecays->GetDecayChannel(i);
68  const G4int nDaughters = aDecay->GetNumberOfDaughters();
69 
70  G4double minChannelMass = 0;
71 
72  for (G4int j=0; j<nDaughters; j++)
73  {
74  const G4ParticleDefinition* aDaughter = const_cast<G4VDecayChannel*>(aDecay)->GetDaughter(j);
75  G4double minMass = GetMinimumMass(aDaughter);
76  if (!minMass) minMass = DBL_MAX; // exclude gamma channel;
77  minChannelMass+=minMass;
78  }
79  // G4cout << "channel mass for the above is " << minChannelMass/MeV << G4endl;
80  if (minChannelMass < minResonanceMass) minResonanceMass = minChannelMass;
81 
82  }
83  // replace this as soon as the compiler supports mutable!!
84  G4SampleResonance* self = const_cast<G4SampleResonance*>(this);
85  //Andrea Dotti (13Jan2013): Change needed for G4MT
86  //(self->minMassCache)[p] = minResonanceMass;
87  self->minMassCache_G4MT_TLS_->operator[](p) = minResonanceMass;
88 
89  }
90  }
91  else
92  {
93 
94  minResonanceMass = p->GetPDGMass();
95 
96  }
97  // G4cout << "minimal mass for " << p->GetParticleName() << " is " << minResonanceMass/MeV << G4endl;
98 
99  return minResonanceMass;
100 }
101 
102 
103 
106  return SampleMass(p->GetPDGMass(), p->GetPDGWidth(), GetMinimumMass(p), maxMass);
107 }
108 
109 
111  const G4double gamma,
112  const G4double minMass,
113  const G4double maxMass) const
115  // Chooses a mass randomly between minMass and maxMass
116  // according to a Breit-Wigner function with constant
117  // width gamma and pole poleMass
118 
119  if ( minMass > maxMass )
120  {
121  throw G4HadronicException(__FILE__, __LINE__,
122  "SampleResonanceMass: mass range negative (minMass>maxMass)");
123  }
124 
125  G4double returnMass;
126 
127  if ( gamma < DBL_EPSILON )
128  {
129  returnMass = std::max(minMass, std::min(maxMass, poleMass));
130  }
131  else
132  {
133  double fmin = BrWigInt0(minMass, gamma, poleMass);
134  double fmax = BrWigInt0(maxMass, gamma, poleMass);
135  double f = fmin + (fmax-fmin)*G4UniformRand();
136  returnMass = BrWigInv(f, gamma, poleMass);
137  }
138 
139  return returnMass;
140 }
141 
142 
143 
144 
G4double SampleMass(const G4double poleMass, const G4double gamma, const G4double minMass, const G4double maxMass) const
static G4ThreadLocal minMassMapType * minMassCache_G4MT_TLS_
G4int GetNumberOfDaughters() const
G4double BrWigInt0(const G4double x, const G4double gamma, const G4double m0) const
G4VDecayChannel * GetDecayChannel(G4int index) const
#define G4ThreadLocal
Definition: tls.hh:84
int G4int
Definition: G4Types.hh:78
G4int entries() const
G4DecayTable * GetDecayTable() const
G4double GetPDGWidth() const
#define G4UniformRand()
Definition: Randomize.hh:95
#define DBL_EPSILON
Definition: templates.hh:87
std::map< const G4ParticleDefinition *, G4double, std::less< const G4ParticleDefinition * > >::const_iterator minMassMapIterator
G4double GetMinimumMass(const G4ParticleDefinition *p) const
G4double GetPDGMass() const
T max(const T t1, const T t2)
brief Return the largest of the two arguments
G4double BrWigInv(const G4double x, const G4double gamma, const G4double m0) const
T min(const T t1, const T t2)
brief Return the smallest of the two arguments
double G4double
Definition: G4Types.hh:76
std::map< const G4ParticleDefinition *, G4double, std::less< const G4ParticleDefinition * > > minMassMapType
#define DBL_MAX
Definition: templates.hh:83