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25 // 25 //
26 // G4ILawTruncatedExp <<
27 // ------------------------------------------- <<
28 <<
29 #include "G4ILawTruncatedExp.hh" 26 #include "G4ILawTruncatedExp.hh"
30 #include "Randomize.hh" 27 #include "Randomize.hh"
31 #include "G4Track.hh" 28 #include "G4Track.hh"
32 29
33 30
34 G4ILawTruncatedExp::G4ILawTruncatedExp(const G << 31 G4ILawTruncatedExp::G4ILawTruncatedExp(G4String name)
35 : G4VBiasingInteractionLaw(name) << 32 : G4VBiasingInteractionLaw(name),
>> 33 fMaximumDistance(0.0),
>> 34 fCrossSection(0.0),
>> 35 fCrossSectionDefined(false),
>> 36 fIsSingular(false)
36 {} 37 {}
37 38
38 G4ILawTruncatedExp::~G4ILawTruncatedExp() 39 G4ILawTruncatedExp::~G4ILawTruncatedExp()
39 {} 40 {}
40 41
41 void G4ILawTruncatedExp::SetForceCrossSection( 42 void G4ILawTruncatedExp::SetForceCrossSection(G4double crossSection)
42 { 43 {
43 if (crossSection < 0.0) 44 if (crossSection < 0.0)
44 { << 45 {
45 G4Exception("G4ILawTruncatedExp::SetForceC << 46 G4Exception("G4ILawTruncatedExp::SetForceCrossSection(..)",
46 "BIAS.GEN.09", JustWarning, << 47 "BIAS.GEN.09",
47 "Cross-section value passed is << 48 JustWarning,
48 fIsSingular = true; << 49 "Cross-section value passed is negative. It is set to zero !");
49 crossSection = 0.0; << 50 fIsSingular = true;
50 } << 51 crossSection = 0.0;
51 fIsSingular = false; << 52 }
>> 53 fIsSingular = false;
52 fCrossSectionDefined = true; 54 fCrossSectionDefined = true;
53 fCrossSection = crossSection; << 55 fCrossSection = crossSection;
54 } 56 }
55 57
56 G4double G4ILawTruncatedExp:: << 58 G4double G4ILawTruncatedExp::ComputeEffectiveCrossSectionAt(G4double distance) const
57 ComputeEffectiveCrossSectionAt(G4double distan <<
58 { 59 {
59 if ( !fCrossSectionDefined ) 60 if ( !fCrossSectionDefined )
60 { << 61 {
61 G4Exception("G4ILawTruncatedExp::ComputeEf << 62 G4Exception("G4ILawTruncatedExp::ComputeEffectiveCrossSection(..)",
62 "BIAS.GEN.10", JustWarning, << 63 "BIAS.GEN.10",
63 "Cross-section value requested << 64 JustWarning,
64 // -- zero cross-section, returns the limi << 65 "Cross-section value requested, but has not been defined yet. Assumes 0 !");
65 return 1.0 / ( fMaximumDistance - distance << 66 // -- zero cross-section, returns the limit form of the effective cross-section:
66 } << 67 return 1.0 / ( fMaximumDistance - distance );
67 << 68 }
68 G4double denum = 1.0 - std::exp(-fCrossSecti << 69 G4double denum = 1.0 - std::exp( -fCrossSection * ( fMaximumDistance - distance) );
69 return fCrossSection/denum; << 70 return fCrossSection / denum;
70 } 71 }
71 72
72 G4double G4ILawTruncatedExp:: << 73 G4double G4ILawTruncatedExp::ComputeNonInteractionProbabilityAt(G4double distance) const
73 ComputeNonInteractionProbabilityAt(G4double di <<
74 { 74 {
75 if (!fCrossSectionDefined) 75 if (!fCrossSectionDefined)
76 { << 76 {
77 G4Exception("G4ILawTruncatedExp::ComputeNo << 77 G4Exception("G4ILawTruncatedExp::ComputeNonInteractionProbability(..)",
78 "BIAS.GEN.11", JustWarning, << 78 "BIAS.GEN.11",
79 "Non interaction probability v << 79 JustWarning,
80 // -- return limit case of null cross-sect << 80 "Non interaction probability value requested, but cross section has not been defined yet. Assumes it to be 0 !");
81 return 1.0 - distance / fMaximumDistance; << 81 // -- return limit case of null cross-section:
82 } << 82 return 1.0 - distance / fMaximumDistance;
>> 83 }
83 G4double num = 1.0 - std::exp( -fCrossSect 84 G4double num = 1.0 - std::exp( -fCrossSection*distance );
84 G4double denum = 1.0 - std::exp( -fCrossSect 85 G4double denum = 1.0 - std::exp( -fCrossSection*fMaximumDistance );
85 return 1.0 - num/denum; 86 return 1.0 - num/denum;
86 } 87 }
87 88
88 G4double G4ILawTruncatedExp::SampleInteraction 89 G4double G4ILawTruncatedExp::SampleInteractionLength()
89 { 90 {
90 if ( !fCrossSectionDefined ) 91 if ( !fCrossSectionDefined )
91 { << 92 {
92 G4Exception("G4ILawTruncatedExp::Sample(.. << 93 G4Exception("G4ILawTruncatedExp::Sample(..)",
93 "BIAS.GEN.12", JustWarning, << 94 "BIAS.GEN.12",
94 "Trying to sample while cross- << 95 JustWarning,
95 fInteractionDistance = G4UniformRand() * f << 96 "Trying to sample while cross-section is not defined, assuming 0 !");
96 return fInteractionDistance; << 97 fInteractionDistance = G4UniformRand() * fMaximumDistance;
97 } << 98 return fInteractionDistance;
98 fInteractionDistance = -std::log(1.0-G4Unifo << 99 }
>> 100 fInteractionDistance = -std::log(1.0 - G4UniformRand()* (1.0 - std::exp(-fCrossSection*fMaximumDistance)))/fCrossSection;
99 return fInteractionDistance; 101 return fInteractionDistance;
100 } 102 }
101 103
102 G4double G4ILawTruncatedExp:: << 104
103 UpdateInteractionLengthForStep(G4double truePa << 105 G4double G4ILawTruncatedExp::UpdateInteractionLengthForStep(G4double truePathLength)
104 { 106 {
105 fInteractionDistance -= truePathLength; 107 fInteractionDistance -= truePathLength;
106 fMaximumDistance -= truePathLength; 108 fMaximumDistance -= truePathLength;
107 109
108 if ( fInteractionDistance < 0 ) 110 if ( fInteractionDistance < 0 )
109 { << 111 {
110 G4ExceptionDescription ed; << 112 G4ExceptionDescription ed;
111 ed << " Negative number of interaction len << 113 ed << " Negative number of interaction length for `" << GetName() << "' " << fInteractionDistance << ", set it to zero !" << G4endl;
112 << "' " << fInteractionDistance << ", s << 114 G4Exception("G4ILawTruncatedExp::UpdateInteractionLengthForStep(...)",
113 G4Exception("G4ILawTruncatedExp::UpdateInt << 115 "BIAS.GEN.13",
114 "BIAS.GEN.13", JustWarning, << 116 JustWarning,
115 "Trying to sample while cross- << 117 "Trying to sample while cross-section is not defined, assuming 0 !");
116 fInteractionDistance = 0.; << 118 fInteractionDistance = 0.;
117 } << 119 }
118 << 120
119 return fInteractionDistance; 121 return fInteractionDistance;
120 } 122 }
121 123