G4SmpNuDistDataU232_234_236_238.cc

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// $Id: G4SmpNuDistDataU232_234_236_238.cc 67966 2013-03-13 09:38:38Z gcosmo $
//

#include <cmath>
#include "G4fissionEvent.hh"

G4int G4fissionEvent::G4SmpNuDistDataU232_234_236_238(G4double nubar) {

/*
  Description
    Sample Number of Neutrons from fission in U-232, U-234, U-236 
    and U-238 using Zucker and Holden's tabulated data for U-238
    The P(nu) distribution is given as a function of the average 
    number of neutrons from fission, based on interpolation of the 
    U-238 data from Zucker and Holden.
*/

/*
  Input
    nubar    - average number of neutrons per fission
  Output
    G4SmpNuDistDataU232_234_236_238  - sampled multiplicity
    
*/

  G4double pnu[9], cpnu, sum;
  G4double r;

/* 
  Check if nubar is within the range of experimental values
*/
  if (nubar >= 2.25 && nubar <= 3.80) {
/*
     Use Zucker and Holden Data
*/
     pnu[0]=-7.705432e-3*std::pow(nubar,3)+8.904671e-2*std::pow(nubar,2)-3.488123e-1*nubar+4.627291e-1;
     pnu[1]=-2.879938e-2*std::pow(nubar,3)+3.629189e-1*std::pow(nubar,2)-1.545284*nubar+2.229503;
     pnu[2]=6.543684e-2*std::pow(nubar,3)-6.673117e-1*std::pow(nubar,2)+2.087358*nubar-1.771396;
     pnu[3]=1.412971e-2*std::pow(nubar,3)-2.309842e-1*std::pow(nubar,2)+1.022451*nubar-1.032235;
     pnu[4]=-5.163167e-2*std::pow(nubar,3)+4.457516e-1*std::pow(nubar,2)-1.114981*nubar+9.484241e-1;
     pnu[5]=8.758841e-4*std::pow(nubar,3)+3.707461e-2*std::pow(nubar,2)-1.565149e-1*nubar+1.851039e-1;
     pnu[6]=-3.871089e-5*std::pow(nubar,3)+1.936524e-2*std::pow(nubar,2)-8.091057e-2*nubar+9.019871e-2;
     pnu[7]=3.945995e-3*std::pow(nubar,3)-2.697509e-2*std::pow(nubar,2)+6.237296e-2*nubar-4.820745e-2;
     pnu[8]=1.708054e-3*std::pow(nubar,4)-1.706039e-2*std::pow(nubar,3)+6.550213e-2*std::pow(nubar,2)-1.135e-1*nubar+7.443828e-2;

     sum=pnu[0]+pnu[1]+pnu[2]+pnu[3]+pnu[4]+pnu[5]+pnu[6]+pnu[7]+pnu[8];

     pnu[0]=pnu[0]/sum;
     pnu[1]=pnu[1]/sum;
     pnu[2]=pnu[2]/sum;
     pnu[3]=pnu[3]/sum;
     pnu[4]=pnu[4]/sum;
     pnu[5]=pnu[5]/sum;
     pnu[6]=pnu[6]/sum;
     pnu[7]=pnu[7]/sum;
     pnu[8]=pnu[8]/sum;

     r=fisslibrng();

     if(r <= pnu[0]) return 0;

     cpnu=pnu[0]+pnu[1];
     if(r <= cpnu) return 1;

     cpnu=cpnu+pnu[2];
     if(r <= cpnu) return 2;

     cpnu=cpnu+pnu[3];
     if(r <= cpnu) return 3;

     cpnu=cpnu+pnu[4];
     if(r <= cpnu) return 4;

     cpnu=cpnu+pnu[5];
     if(r <= cpnu) return 5;

     cpnu=cpnu+pnu[6];
     if(r <= cpnu) return 6;

     cpnu=cpnu+pnu[7];
     if(r <= cpnu) return 7;
     else return 8;

  } else {
/*
     Use Terrell's formula
*/
     return (G4int) G4SmpTerrell(nubar);
  }
}