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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 "G4Pow.hh"
60 #include "G4fissionEvent.hh"
61
62 G4int G4fissionEvent::G4SmpNuDistDataPu239_241(G4double nubar) {
63
64 /*
65 Description
66 Sample Number of Neutrons from fission in Pu-239 and Pu-241 using
67 Zucker and Holden's tabulated data for Pu-239
68 The P(nu) distribution is given as a function of the average
69 number of neutrons from fission, based on interpolation of the
70 Pu-239 data from Zucker and Holden.
71 */
72
73 /*
74 Input
75 nubar - average number of neutrons per fission
76 Output
77 G4SmpNuDistDataPu239_241 - sampled multiplicity
78
79 */
80
81 G4double pnu[9], cpnu, sum;
82 G4double r;
83
84 /*
85 Check if nubar is within the range of experimental values
86 */
87 if(nubar >= 2.85 && nubar <= 4.25) {
88 /*
89 Use Zucker and Holden Data
90 */
91 G4Pow* Pow=G4Pow::GetInstance();
92 pnu[0]=-2.412937e-3*Pow->powN(nubar,3)+3.210687e-2*Pow->powN(nubar,2)-1.434037e-1*nubar+2.150733e-1;
93 pnu[1]=-2.650615e-2*Pow->powN(nubar,3)+3.290389e-1*Pow->powN(nubar,2)-1.389007*nubar+2.002327;
94 pnu[2]=3.232028e-2*Pow->powN(nubar,3)-3.176093e-1*Pow->powN(nubar,2)+8.605098e-1*nubar-3.411191e-1;
95 pnu[3]=1.623289e-2*Pow->powN(nubar,3)-2.414705e-1*Pow->powN(nubar,2)+1.007282*nubar-9.583769e-1;
96 pnu[4]=1.932275e-2*Pow->powN(nubar,3)-2.923666e-1*Pow->powN(nubar,2)+1.421383*nubar-1.924025;
97 pnu[5]=-6.185679e-2*Pow->powN(nubar,3)+6.82888e-1*Pow->powN(nubar,2)-2.347653*nubar+2.647049;
98 pnu[6]=1.79773e-2*Pow->powN(nubar,3)-1.60516e-1*Pow->powN(nubar,2)+5.228077e-1*nubar-5.939556e-1;
99 pnu[7]=3.530038e-3*Pow->powN(nubar,4)-4.925425e-2*Pow->powN(nubar,3)+2.726784e-1*Pow->powN(nubar,2)-6.81281e-1*nubar+6.347577e-1;
100 pnu[8]=2.837523e-3*Pow->powN(nubar,3)-2.678644e-2*Pow->powN(nubar,2)+8.545638e-2*nubar-9.156078e-2;
101
102 sum=pnu[0]+pnu[1]+pnu[2]+pnu[3]+pnu[4]+pnu[5]+pnu[6]+pnu[7]+pnu[8];
103
104 pnu[0]=pnu[0]/sum;
105 pnu[1]=pnu[1]/sum;
106 pnu[2]=pnu[2]/sum;
107 pnu[3]=pnu[3]/sum;
108 pnu[4]=pnu[4]/sum;
109 pnu[5]=pnu[5]/sum;
110 pnu[6]=pnu[6]/sum;
111 pnu[7]=pnu[7]/sum;
112 pnu[8]=pnu[8]/sum;
113
114 r=fisslibrng();
115
116 if(r <= pnu[0]) return 0;
117
118 cpnu=pnu[0]+pnu[1];
119 if(r <= cpnu) return 1;
120
121 cpnu=cpnu+pnu[2];
122 if(r <= cpnu) return 2;
123
124 cpnu=cpnu+pnu[3];
125 if(r <= cpnu) return 3;
126
127 cpnu=cpnu+pnu[4];
128 if(r <= cpnu) return 4;
129
130 cpnu=cpnu+pnu[5];
131 if(r <= cpnu) return 5;
132
133 cpnu=cpnu+pnu[6];
134 if(r <= cpnu) return 6;
135
136 cpnu=cpnu+pnu[7];
137 if(r <= cpnu) return 7;
138 else return 8;
139
140 } else {
141 /*
142 Use Terrell's formula
143 */
144 return (G4int) G4SmpTerrell(nubar);
145 }
146 }
147