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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
>> 30 //#include "G4Exception.hh"
33 31
34 G4ILawTruncatedExp::G4ILawTruncatedExp(const G << 32 G4ILawTruncatedExp::G4ILawTruncatedExp(G4String name)
35 : G4VBiasingInteractionLaw(name) << 33 : G4VBiasingInteractionLaw(name),
>> 34 fMaximumDistance(0.0),
>> 35 fCrossSection(0.0),
>> 36 fCrossSectionDefined(false),
>> 37 fIsSingular(false)
36 {} 38 {}
37 39
38 G4ILawTruncatedExp::~G4ILawTruncatedExp() 40 G4ILawTruncatedExp::~G4ILawTruncatedExp()
39 {} 41 {}
40 42
41 void G4ILawTruncatedExp::SetForceCrossSection( 43 void G4ILawTruncatedExp::SetForceCrossSection(G4double crossSection)
42 { 44 {
43 if (crossSection < 0.0) 45 if (crossSection < 0.0)
44 { << 46 {
45 G4Exception("G4ILawTruncatedExp::SetForceC << 47 G4Exception("G4ILawTruncatedExp::SetForceCrossSection(..)",
46 "BIAS.GEN.09", JustWarning, << 48 "BIAS.GEN.09",
47 "Cross-section value passed is << 49 JustWarning,
48 fIsSingular = true; << 50 "Cross-section value passed is negative. It is set to zero !");
49 crossSection = 0.0; << 51 fIsSingular = true;
50 } << 52 crossSection = 0.0;
51 fIsSingular = false; << 53 }
>> 54 fIsSingular = false;
52 fCrossSectionDefined = true; 55 fCrossSectionDefined = true;
53 fCrossSection = crossSection; << 56 fCrossSection = crossSection;
54 } 57 }
55 58
56 G4double G4ILawTruncatedExp:: << 59 G4double G4ILawTruncatedExp::ComputeEffectiveCrossSectionAt(G4double distance) const
57 ComputeEffectiveCrossSectionAt(G4double distan <<
58 { 60 {
59 if ( !fCrossSectionDefined ) 61 if ( !fCrossSectionDefined )
60 { << 62 {
61 G4Exception("G4ILawTruncatedExp::ComputeEf << 63 G4Exception("G4ILawTruncatedExp::ComputeEffectiveCrossSection(..)",
62 "BIAS.GEN.10", JustWarning, << 64 "BIAS.GEN.10",
63 "Cross-section value requested << 65 JustWarning,
64 // -- zero cross-section, returns the limi << 66 "Cross-section value requested, but has not been defined yet. Assumes 0 !");
65 return 1.0 / ( fMaximumDistance - distance << 67 // -- zero cross-section, returns the limit form of the effective cross-section:
66 } << 68 return 1.0 / ( fMaximumDistance - distance );
67 << 69 }
68 G4double denum = 1.0 - std::exp(-fCrossSecti << 70 G4double denum = 1.0 - std::exp( -fCrossSection * ( fMaximumDistance - distance) );
69 return fCrossSection/denum; << 71 return fCrossSection / denum;
70 } 72 }
71 73
72 G4double G4ILawTruncatedExp:: << 74 G4double G4ILawTruncatedExp::ComputeNonInteractionProbabilityAt(G4double distance) const
73 ComputeNonInteractionProbabilityAt(G4double di <<
74 { 75 {
75 if (!fCrossSectionDefined) 76 if (!fCrossSectionDefined)
76 { << 77 {
77 G4Exception("G4ILawTruncatedExp::ComputeNo << 78 G4Exception("G4ILawTruncatedExp::ComputeNonInteractionProbability(..)",
78 "BIAS.GEN.11", JustWarning, << 79 "BIAS.GEN.11",
79 "Non interaction probability v << 80 JustWarning,
80 // -- return limit case of null cross-sect << 81 "Non interaction probability value requested, but cross section has not been defined yet. Assumes it to be 0 !");
81 return 1.0 - distance / fMaximumDistance; << 82 // -- return limit case of null cross-section:
82 } << 83 return 1.0 - distance / fMaximumDistance;
83 G4double num = 1.0 - std::exp( -fCrossSect << 84 }
84 G4double denum = 1.0 - std::exp( -fCrossSect << 85 G4double num = 1.0 - std::exp( -fCrossSection*distance);
>> 86 G4double denum = 1.0 - std::exp( -fCrossSection*fMaximumDistance);
85 return 1.0 - num/denum; 87 return 1.0 - num/denum;
86 } 88 }
87 89
88 G4double G4ILawTruncatedExp::SampleInteraction 90 G4double G4ILawTruncatedExp::SampleInteractionLength()
89 { 91 {
90 if ( !fCrossSectionDefined ) 92 if ( !fCrossSectionDefined )
91 { << 93 {
92 G4Exception("G4ILawTruncatedExp::Sample(.. << 94 G4Exception("G4ILawTruncatedExp::Sample(..)",
93 "BIAS.GEN.12", JustWarning, << 95 "BIAS.GEN.12",
94 "Trying to sample while cross- << 96 JustWarning,
95 fInteractionDistance = G4UniformRand() * f << 97 "Trying to sample while cross-section is not defined, assuming 0 !");
96 return fInteractionDistance; << 98 fInteractionDistance = G4UniformRand() * fMaximumDistance;
97 } << 99 return fInteractionDistance;
98 fInteractionDistance = -std::log(1.0-G4Unifo << 100 }
>> 101 fInteractionDistance = -std::log(1.0 - G4UniformRand()* (1.0 - std::exp(-fCrossSection*fMaximumDistance)))/fCrossSection;
99 return fInteractionDistance; 102 return fInteractionDistance;
100 } 103 }
101 104
102 G4double G4ILawTruncatedExp:: << 105
103 UpdateInteractionLengthForStep(G4double truePa << 106 G4double G4ILawTruncatedExp::UpdateInteractionLengthForStep(G4double truePathLength)
104 { 107 {
105 fInteractionDistance -= truePathLength; 108 fInteractionDistance -= truePathLength;
106 fMaximumDistance -= truePathLength; 109 fMaximumDistance -= truePathLength;
107 110
108 if ( fInteractionDistance < 0 ) 111 if ( fInteractionDistance < 0 )
109 { << 112 {
110 G4ExceptionDescription ed; << 113 G4ExceptionDescription ed;
111 ed << " Negative number of interaction len << 114 ed << " Negative number of interaction length for `" << GetName() << "' " << fInteractionDistance << ", set it to zero !" << G4endl;
112 << "' " << fInteractionDistance << ", s << 115 G4Exception("G4ILawTruncatedExp::UpdateInteractionLengthForStep(...)",
113 G4Exception("G4ILawTruncatedExp::UpdateInt << 116 "BIAS.GEN.13",
114 "BIAS.GEN.13", JustWarning, << 117 JustWarning,
115 "Trying to sample while cross- << 118 "Trying to sample while cross-section is not defined, assuming 0 !");
116 fInteractionDistance = 0.; << 119 fInteractionDistance = 0.;
117 } << 120 }
118 << 121
119 return fInteractionDistance; 122 return fInteractionDistance;
120 } 123 }
121 124