Geant4  10.03.p03
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G4ILawTruncatedExp.cc
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26 #include "G4ILawTruncatedExp.hh"
27 #include "Randomize.hh"
28 #include "G4Track.hh"
29 
30 
33  fMaximumDistance(0.0),
34  fCrossSection(0.0),
35  fCrossSectionDefined(false),
36  fIsSingular(false)
37 {}
38 
40 {}
41 
43 {
44  if (crossSection < 0.0)
45  {
46  G4Exception("G4ILawTruncatedExp::SetForceCrossSection(..)",
47  "BIAS.GEN.09",
49  "Cross-section value passed is negative. It is set to zero !");
50  fIsSingular = true;
51  crossSection = 0.0;
52  }
53  fIsSingular = false;
54  fCrossSectionDefined = true;
55  fCrossSection = crossSection;
56 }
57 
59 {
60  if ( !fCrossSectionDefined )
61  {
62  G4Exception("G4ILawTruncatedExp::ComputeEffectiveCrossSection(..)",
63  "BIAS.GEN.10",
65  "Cross-section value requested, but has not been defined yet. Assumes 0 !");
66  // -- zero cross-section, returns the limit form of the effective cross-section:
67  return 1.0 / ( fMaximumDistance - distance );
68  }
69  G4double denum = 1.0 - std::exp( -fCrossSection * ( fMaximumDistance - distance) );
70  return fCrossSection / denum;
71 }
72 
74 {
75  if (!fCrossSectionDefined)
76  {
77  G4Exception("G4ILawTruncatedExp::ComputeNonInteractionProbability(..)",
78  "BIAS.GEN.11",
80  "Non interaction probability value requested, but cross section has not been defined yet. Assumes it to be 0 !");
81  // -- return limit case of null cross-section:
82  return 1.0 - distance / fMaximumDistance;
83  }
84  G4double num = 1.0 - std::exp( -fCrossSection*distance );
85  G4double denum = 1.0 - std::exp( -fCrossSection*fMaximumDistance );
86  return 1.0 - num/denum;
87 }
88 
90 {
91  if ( !fCrossSectionDefined )
92  {
93  G4Exception("G4ILawTruncatedExp::Sample(..)",
94  "BIAS.GEN.12",
96  "Trying to sample while cross-section is not defined, assuming 0 !");
97  fInteractionDistance = G4UniformRand() * fMaximumDistance;
98  return fInteractionDistance;
99  }
100  fInteractionDistance = -std::log(1.0 - G4UniformRand()* (1.0 - std::exp(-fCrossSection*fMaximumDistance)))/fCrossSection;
101  return fInteractionDistance;
102 }
103 
104 
106 {
107  fInteractionDistance -= truePathLength;
108  fMaximumDistance -= truePathLength;
109 
110  if ( fInteractionDistance < 0 )
111  {
113  ed << " Negative number of interaction length for `" << GetName() << "' " << fInteractionDistance << ", set it to zero !" << G4endl;
114  G4Exception("G4ILawTruncatedExp::UpdateInteractionLengthForStep(...)",
115  "BIAS.GEN.13",
116  JustWarning,
117  "Trying to sample while cross-section is not defined, assuming 0 !");
118  fInteractionDistance = 0.;
119  }
120 
121  return fInteractionDistance;
122 }
const XML_Char * name
Definition: expat.h:151
std::ostringstream G4ExceptionDescription
Definition: globals.hh:76
virtual G4double ComputeNonInteractionProbabilityAt(G4double length) const
virtual G4double SampleInteractionLength()
G4ILawTruncatedExp(G4String name="expForceInteractionLaw")
#define G4UniformRand()
Definition: Randomize.hh:97
void G4Exception(const char *originOfException, const char *exceptionCode, G4ExceptionSeverity severity, const char *comments)
Definition: G4Exception.cc:41
virtual G4double UpdateInteractionLengthForStep(G4double truePathLength)
#define G4endl
Definition: G4ios.hh:61
const G4String & GetName() const
double G4double
Definition: G4Types.hh:76
virtual G4double ComputeEffectiveCrossSectionAt(G4double length) const
void SetForceCrossSection(G4double xs)