Geant4  10.03.p02
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G4InteractionLawPhysical.cc
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27 #include "Randomize.hh"
28 
31  fCrossSection(0.0),
32  fCrossSectionDefined(false),
33  fNumberOfInteractionLength(-1.0)
34 {}
35 
37 {}
38 
40 {
41  if (crossSection < 0.0)
42  {
43  G4Exception("G4InteractionLawPhysical::SetPhysicalCrossSection(..)",
44  "BIAS.GEN.14",
46  "Cross-section value passed is negative. It is set to zero !");
47  crossSection = 0.0;
48  }
49  fCrossSectionDefined = true;
50  fCrossSection = crossSection;
51 }
52 
54 {
55  if (!fCrossSectionDefined) G4Exception("G4InteractionLawPhysical::ComputeEffectiveCrossSection(..)",
56  "BIAS.GEN.15",
58  "Cross-section value requested, but has not been defined yet. Assumes 0 !");
59  return fCrossSection;
60 }
61 
63 {
64  if (!fCrossSectionDefined) G4Exception("G4InteractionLawPhysical::ComputeNonInteractionProbability(..)",
65  "BIAS.GEN.16",
67  "Non interaction probabitlity value requested, but cross section has not been defined yet. Assumes it to be 0 !");
68  // -- allows zero cross-section case, by convention:
69  if ( fCrossSection == 0.0 ) return 1.0;
70  else return std::exp(-fCrossSection*stepLength);
71 }
72 
74 {
75  if ( !fCrossSectionDefined || fCrossSection < 0.0 ) G4Exception("G4InteractionLawPhysical::Sample(..)",
76  "BIAS.GEN.17",
78  "Trying to sample while cross-section is not defined or < 0 !");
79  if ( fCrossSection == 0.0 ) return DBL_MAX;
80 
81  fNumberOfInteractionLength = -std::log( G4UniformRand() );
82  return fNumberOfInteractionLength/fCrossSection;
83 }
84 
85 
87 {
88  fNumberOfInteractionLength -= truePathLength*fCrossSection;
89 
90  if ( fNumberOfInteractionLength < 0 )
91  {
93  ed << " Negative number of interaction length for `" << GetName() << "' " << fNumberOfInteractionLength << ", set it to zero !" << G4endl;
94  G4Exception("G4InteractionLawPhysical::UpdateInteractionLengthForStep(...)",
95  "BIAS.GEN.13",
97  ed);
98  fNumberOfInteractionLength = 0.;
99  }
100  return fNumberOfInteractionLength/fCrossSection;
101 }
const XML_Char * name
Definition: expat.h:151
virtual G4double ComputeNonInteractionProbabilityAt(G4double length) const
std::ostringstream G4ExceptionDescription
Definition: globals.hh:76
virtual G4double UpdateInteractionLengthForStep(G4double truePathLength)
G4InteractionLawPhysical(G4String name="exponentialLaw")
virtual G4double SampleInteractionLength()
#define G4UniformRand()
Definition: Randomize.hh:97
virtual G4double ComputeEffectiveCrossSectionAt(G4double length) const
void SetPhysicalCrossSection(G4double crossSection)
void G4Exception(const char *originOfException, const char *exceptionCode, G4ExceptionSeverity severity, const char *comments)
Definition: G4Exception.cc:41
#define G4endl
Definition: G4ios.hh:61
const G4String & GetName() const
double G4double
Definition: G4Types.hh:76
#define DBL_MAX
Definition: templates.hh:83