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51 // Copyright (c) 2006 The Regents of the University of California.
52 // All rights reserved.
53 // UCRL-CODE-224807
54 //
55 //
56 //
57
58 #include <cmath>
59 #include "G4fissionEvent.hh"
60 #include "G4Exp.hh"
61 #include "G4Log.hh"
62 #include "G4Pow.hh"
63
64 #define nfissg 40
65 #define alphanegbin 26
66
67 G4int G4fissionEvent::G4SmpNugDist(G4int isotope, G4double nubar) {
68
69 /*
70 Description
71 Sample Number of Photons from neutron induced fission in
72 all isotopes using Tim Valentine's model (negative binomial
73 distribution, using nubar as a model parameter)
74 */
75
76 /*
77 Input
78 iso - isotope
79 Output
80 G4SmpNugDist - sampled multiplicity
81 */
82
83 static G4double logcoeff[nfissg+1] = {
84 0.00000000000000e+00,
85 3.25809653802149e+00,
86 5.86078622346587e+00,
87 8.09437844497297e+00,
88 1.00753799138395e+01,
89 1.18671393830676e+01,
90 1.35093671183247e+01,
91 1.50291928720691e+01,
92 1.64462588918558e+01,
93 1.77753948391357e+01,
94 1.90281578076311e+01,
95 2.02137814732888e+01,
96 2.13397927361450e+01,
97 2.24124295384099e+01,
98 2.34369338549243e+01,
99 2.44177631079360e+01,
100 2.53587464524005e+01,
101 2.62632027266277e+01,
102 2.71340310844251e+01,
103 2.79737817391769e+01,
104 2.87847119553932e+01,
105 2.95688309141589e+01,
106 3.03279360625106e+01,
107 3.10636428574894e+01,
108 3.17774093252521e+01,
109 3.24705565058120e+01,
110 3.31442856005149e+01,
111 3.37996924530920e+01,
112 3.44377798564689e+01,
113 3.50594680730467e+01,
114 3.56656038766170e+01,
115 3.62569683628670e+01,
116 3.68342837279018e+01,
117 3.73982191769817e+01,
118 3.79493960962713e+01,
119 3.84883925970040e+01,
120 3.90157475227212e+01,
121 3.95319639951220e+01,
122 4.00375125617872e+01,
123 4.05328339990172e+01,
124 4.10183418147990e+01
125 };
126 G4int i, A, Z;
127 G4double cpi[nfissg+1];
128 G4double p, q, nubarg;
129 G4double r;
130
131 /*
132 No data is available for induced fission gamma number
133 distributions. Sample the negative binomial cumulative
134 probability distribution.
135 */
136 A = (G4int) (isotope-1000*((G4int)(isotope/1000)));
137 Z = (G4int) ((isotope-A)/1000);
138 G4Pow* Pow = G4Pow::GetInstance();
139 nubarg = ((2.51-1.13e-5*Pow->powA(G4double(Z),2.)*std::sqrt(G4double(A)))*nubar+4.0)
140 /(-1.33+119.6*Pow->A13(G4double(Z))/G4double(A));
141 p = 1.*alphanegbin/(alphanegbin+nubarg);
142 q = 1.-p;
143 cpi[0] = G4Exp(logcoeff[0]+26.*G4Log(p));
144 for (i=1; i<=nfissg; i++) cpi[i] = cpi[i-1] + G4Exp(logcoeff[i]+26.*G4Log(p)+i*G4Log(q));
145 for (i=0; i<=nfissg; i++) cpi[i] = cpi[i]/cpi[nfissg-1];
146
147 r=fisslibrng();
148
149 for(i=0; i<=nfissg; i++) if (r <= cpi[i]) return i;
150
151 //
152 // Fall through
153 //
154
155 G4cout << " SmpNugDist: random number " << r << " out of range " << G4endl;
156 return -1;
157
158 }
159