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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::G4SmpNuDistDataU232_234_236_238(G4double nubar) {
63
64 /*
65 Description
66 Sample Number of Neutrons from fission in U-232, U-234, U-236
67 and U-238 using Zucker and Holden's tabulated data for U-238
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 U-238 data from Zucker and Holden.
71 */
72
73 /*
74 Input
75 nubar - average number of neutrons per fission
76 Output
77 G4SmpNuDistDataU232_234_236_238 - 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 >= 2.25 && nubar <= 3.80) {
88 /*
89 Use Zucker and Holden Data
90 */
91 G4Pow* Pow=G4Pow::GetInstance();
92 pnu[0]=-7.705432e-3*Pow->powN(nubar,3)+8.904671e-2*Pow->powN(nubar,2)-3.488123e-1*nubar+4.627291e-1;
93 pnu[1]=-2.879938e-2*Pow->powN(nubar,3)+3.629189e-1*Pow->powN(nubar,2)-1.545284*nubar+2.229503;
94 pnu[2]=6.543684e-2*Pow->powN(nubar,3)-6.673117e-1*Pow->powN(nubar,2)+2.087358*nubar-1.771396;
95 pnu[3]=1.412971e-2*Pow->powN(nubar,3)-2.309842e-1*Pow->powN(nubar,2)+1.022451*nubar-1.032235;
96 pnu[4]=-5.163167e-2*Pow->powN(nubar,3)+4.457516e-1*Pow->powN(nubar,2)-1.114981*nubar+9.484241e-1;
97 pnu[5]=8.758841e-4*Pow->powN(nubar,3)+3.707461e-2*Pow->powN(nubar,2)-1.565149e-1*nubar+1.851039e-1;
98 pnu[6]=-3.871089e-5*Pow->powN(nubar,3)+1.936524e-2*Pow->powN(nubar,2)-8.091057e-2*nubar+9.019871e-2;
99 pnu[7]=3.945995e-3*Pow->powN(nubar,3)-2.697509e-2*Pow->powN(nubar,2)+6.237296e-2*nubar-4.820745e-2;
100 pnu[8]=1.708054e-3*Pow->powN(nubar,4)-1.706039e-2*Pow->powN(nubar,3)+6.550213e-2*Pow->powN(nubar,2)-1.135e-1*nubar+7.443828e-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