1 | // |
---|
2 | // ******************************************************************** |
---|
3 | // * License and Disclaimer * |
---|
4 | // * * |
---|
5 | // * The Geant4 software is copyright of the Copyright Holders of * |
---|
6 | // * the Geant4 Collaboration. It is provided under the terms and * |
---|
7 | // * conditions of the Geant4 Software License, included in the file * |
---|
8 | // * LICENSE and available at http://cern.ch/geant4/license . These * |
---|
9 | // * include a list of copyright holders. * |
---|
10 | // * * |
---|
11 | // * Neither the authors of this software system, nor their employing * |
---|
12 | // * institutes,nor the agencies providing financial support for this * |
---|
13 | // * work make any representation or warranty, express or implied, * |
---|
14 | // * regarding this software system or assume any liability for its * |
---|
15 | // * use. Please see the license in the file LICENSE and URL above * |
---|
16 | // * for the full disclaimer and the limitation of liability. * |
---|
17 | // * * |
---|
18 | // * This code implementation is the result of the scientific and * |
---|
19 | // * technical work of the GEANT4 collaboration. * |
---|
20 | // * By using, copying, modifying or distributing the software (or * |
---|
21 | // * any work based on the software) you agree to acknowledge its * |
---|
22 | // * use in resulting scientific publications, and indicate your * |
---|
23 | // * acceptance of all terms of the Geant4 Software license. * |
---|
24 | // ******************************************************************** |
---|
25 | // |
---|
26 | // |
---|
27 | // Implementation of the HETC88 code into Geant4. |
---|
28 | // Evaporation and De-excitation parts |
---|
29 | // T. Lampen, Helsinki Institute of Physics, May-2000 |
---|
30 | |
---|
31 | #include "globals.hh" |
---|
32 | #include "G4ios.hh" |
---|
33 | #include "Randomize.hh" |
---|
34 | #include "G4Neutron.hh" |
---|
35 | #include "G4Proton.hh" |
---|
36 | #include "G4Deuteron.hh" |
---|
37 | #include "G4Triton.hh" |
---|
38 | #include "G4Alpha.hh" |
---|
39 | #include "G4ParticleTable.hh" |
---|
40 | #include "G4Nucleus.hh" |
---|
41 | #include "G4BENeutronChannel.hh" |
---|
42 | |
---|
43 | |
---|
44 | G4BENeutronChannel::G4BENeutronChannel() |
---|
45 | { |
---|
46 | name = "neutron"; |
---|
47 | particleA = 1; |
---|
48 | particleZ = 0; |
---|
49 | verboseLevel = 0; |
---|
50 | rho = 0; |
---|
51 | } |
---|
52 | |
---|
53 | |
---|
54 | G4BENeutronChannel::~G4BENeutronChannel() |
---|
55 | { |
---|
56 | } |
---|
57 | |
---|
58 | |
---|
59 | void G4BENeutronChannel::calculateProbability() |
---|
60 | { |
---|
61 | const G4int residualZ = nucleusZ - particleZ; |
---|
62 | const G4int residualA = nucleusA - particleA; |
---|
63 | |
---|
64 | if ( nucleusA < 2.0 * particleA || |
---|
65 | nucleusZ < 2.0 * particleZ || |
---|
66 | residualA <= residualZ || |
---|
67 | excitationEnergy - getThresh() - correction < 0 ) |
---|
68 | { |
---|
69 | if ( verboseLevel >= 6 ) |
---|
70 | G4cout << "G4BENeutronChannel : calculateProbability = 0 " << G4endl; |
---|
71 | emissionProbability = 0; |
---|
72 | return; |
---|
73 | } |
---|
74 | |
---|
75 | // In HETC88 s-s0 was used in std::exp( s ), in which s0 was either 50 or |
---|
76 | // max(s_i), where i goes over all channels. |
---|
77 | |
---|
78 | const G4double levelParam = getLevelDensityParameter(); |
---|
79 | |
---|
80 | const G4double s = 2 * std::sqrt( levelParam * ( excitationEnergy - getThresh() - correction ) ); |
---|
81 | // const G4double temp = ( std::pow( s, 2. ) - 3 * s + 3 ) / ( 4 * std::pow( levelParam, 2. ) ) |
---|
82 | // + beta() * ( s - 1 ) / ( 2 * levelParam ); |
---|
83 | const G4double eye0 = std::exp( s ) * ( s - 1 ) / ( 2 * levelParam ); |
---|
84 | const G4double eye1 = ( std::pow( s, 2. ) - 3*s +3 ) * std::exp( s ) / ( 4 * std::pow( levelParam, 2. ) ) ; |
---|
85 | |
---|
86 | emissionProbability = std::pow( G4double(residualA), 0.666666 ) * alpha() * ( eye1 + beta() * eye0 ); |
---|
87 | |
---|
88 | if ( verboseLevel >= 6 ) |
---|
89 | G4cout << "G4BENeutronChannel : calculateProbability " << G4endl |
---|
90 | << " res A = " << residualA << G4endl |
---|
91 | << " res Z = " << residualZ << G4endl |
---|
92 | << " alpha = " << alpha() << G4endl |
---|
93 | << " beta = " << beta() << G4endl |
---|
94 | << " E = " << excitationEnergy << G4endl |
---|
95 | << " correction = " << correction << G4endl |
---|
96 | << " eye1 = " << eye1 << G4endl |
---|
97 | << " eye0 = " << eye0 << G4endl |
---|
98 | << " levelParam = " << levelParam << G4endl |
---|
99 | << " thresh = " << getThresh() << G4endl |
---|
100 | << " s = " << s << G4endl |
---|
101 | << " probability = " << emissionProbability << G4endl; |
---|
102 | |
---|
103 | return; |
---|
104 | } |
---|
105 | |
---|
106 | |
---|
107 | G4double G4BENeutronChannel::sampleKineticEnergy() |
---|
108 | { |
---|
109 | // Samples the kinetic energy of the particle in CMS |
---|
110 | // |
---|
111 | // Algorithm used in HETC98 |
---|
112 | // |
---|
113 | // G4double e1; |
---|
114 | // G4double e2; |
---|
115 | // G4double s; |
---|
116 | // G4double levelParam; |
---|
117 | // G4double eye0; |
---|
118 | // G4double eye1; |
---|
119 | // G4double kineticEnergyAv; |
---|
120 | // G4double kineticEnergy; |
---|
121 | |
---|
122 | // e1 = RandExponential::shoot( 1 ); |
---|
123 | // e2 = RandExponential::shoot( 1 ); |
---|
124 | |
---|
125 | // levelParam = getLevelDensityParameter(); |
---|
126 | // s = 2 * std::sqrt( levelParam * ( excitationEnergy - getThresh() - correction ) ); |
---|
127 | // eye0 = 0.5 * ( s - 1 ) * std::exp( s ) / levelParam; |
---|
128 | // eye1 = ( std::pow( s, 2. ) - 3*s + 3 ) * std::exp( s ) / ( 4 * std::pow( levelParam, 2. ) ); |
---|
129 | // kineticEnergyAv = 2 * ( std::pow( s, 3. ) - 6.0 * std::pow( s, 2. ) + 15.0 * s - 15.0 ) / |
---|
130 | // ( ( 2.0 * std::pow( s, 2. ) - 6.0 * s + 6.0 ) * levelParam ); |
---|
131 | // kineticEnergyAv = ( kineticEnergyAv + beta() ) / ( 1.0 + beta() * eye0 |
---|
132 | // / eye1 ); |
---|
133 | |
---|
134 | // kineticEnergy = 0.5 * ( e1 + e2 ) * kineticEnergyAv + getThresh() - getQ(); |
---|
135 | |
---|
136 | //////////////// |
---|
137 | // A random number is sampled from the density function |
---|
138 | // P(x) = x * std::exp ( 2 std::sqrt ( a ( xMax - x ) ) ) [not normalized], |
---|
139 | // x belongs to [ 0, xMax ] |
---|
140 | // with the 'Hit or Miss' -method |
---|
141 | // Kinetic energy is this energy scaled properly |
---|
142 | |
---|
143 | G4double levelParam; |
---|
144 | levelParam = getLevelDensityParameter(); |
---|
145 | |
---|
146 | const G4double xMax = excitationEnergy - getThresh() - correction + beta(); // maximum number |
---|
147 | const G4double xProb = ( - 1 + std::sqrt ( 1 + 4 * levelParam * xMax ) ) / ( 2 * levelParam ); // most probable value |
---|
148 | const G4double m = xProb * std::exp ( 2 * std::sqrt ( levelParam * ( xMax - xProb ) ) ); // maximum value of P(x) |
---|
149 | |
---|
150 | // Sample x according to density function P(x) with rejection method |
---|
151 | G4double r1; |
---|
152 | G4double r2; |
---|
153 | G4int koe=0; |
---|
154 | do |
---|
155 | { |
---|
156 | r1 = beta() + G4UniformRand() * ( xMax - beta() ); |
---|
157 | r2 = G4UniformRand() * m; |
---|
158 | koe++; |
---|
159 | } |
---|
160 | while ( r1 * std::exp ( 2 * std::sqrt ( levelParam * ( xMax - r1 ) ) ) < r2 ); |
---|
161 | |
---|
162 | // G4cout << koe << G4endl; |
---|
163 | G4double kineticEnergy = r1 - beta(); |
---|
164 | |
---|
165 | if ( verboseLevel >= 10 ) |
---|
166 | G4cout << " G4BENeutronChannel : sampleKineticEnergy() " << G4endl |
---|
167 | << " kinetic n e = " << kineticEnergy << G4endl |
---|
168 | << " levelParam = " << levelParam << G4endl |
---|
169 | << " thresh= " << getThresh() << G4endl |
---|
170 | << " beta= " << beta() << G4endl; |
---|
171 | |
---|
172 | return kineticEnergy; |
---|
173 | } |
---|
174 | |
---|
175 | |
---|
176 | G4DynamicParticle * G4BENeutronChannel::emit() |
---|
177 | { |
---|
178 | G4double u; |
---|
179 | G4double v; |
---|
180 | G4double w; |
---|
181 | G4DynamicParticle * pParticle = new G4DynamicParticle; |
---|
182 | |
---|
183 | pParticle -> SetDefinition( G4Neutron::Neutron() ); |
---|
184 | pParticle -> SetKineticEnergy( sampleKineticEnergy() ); |
---|
185 | isotropicCosines( u, v, w ); |
---|
186 | pParticle -> SetMomentumDirection( u , v , w ); |
---|
187 | |
---|
188 | return pParticle; |
---|
189 | } |
---|
190 | |
---|
191 | |
---|
192 | G4double G4BENeutronChannel::alpha() |
---|
193 | { |
---|
194 | const G4double residualA = nucleusA - particleA; |
---|
195 | return 0.76 + 1.93 * std::pow( residualA, -0.33333 ); |
---|
196 | } |
---|
197 | |
---|
198 | |
---|
199 | G4double G4BENeutronChannel::beta() |
---|
200 | { |
---|
201 | G4double residualA = nucleusA - particleA; |
---|
202 | return ( 1.66 * std::pow ( residualA, -0.66666 ) - 0.05 )/alpha()*MeV; |
---|
203 | } |
---|
204 | |
---|