# Using the source_newgen.f file

Dear Fluka Experts,

I am running a fluka simulation that requires sampling my source from a histogram distribution. The source_newgen.f file says I do not need to normalize the bin value dN/dE but I have two problems.

1. Uising the AmBe ISO spectrum: page 14 and 17

This spectrum is reported as the Source strength Bi[s^-1] normalized such that sum(Bi) = 1s^-2. To get the dN/dE from here, I proceeded by dividing the Bi by the bin width Delta_E but the results obtained from Fluka don’t make any sense. Is this right? IF not, then what is the correct approach?

1. Another Spectrum.

In this second specrtum, it is reported the spectral strength Phi(E).Ec against Ec and shown in the file. To proceed, I juts let Phi(E) = dN/dE = (Phi(E)*Ec)/Ec, then I computed the bin width using the formula reported. Is this the correct approach?

1. I also computed the normalized dN/dE as well as the CDF from both spetra but these three approaches all produce three different simulation resluts from FLUKA.

kindly let me know and I will be grateful. Also find attahced the useful files
ISO 8529-1.pdf (330.9 KB)
Source file 2.txt (3.6 KB)

Dear @Zev

to be able to use the histogram sampling in the source_newgen.f the bins should be represented by a minimum and a maximum value.

`dN/dE` is should calculated as:

``````dN/dE (i) = N(i) / (Emax(i) - Emin(i))
``````

where

`N(i)` is the total number of particles in the i^th bin.
`Emax(i)` and `Emin(i)` are the maximum and minimum energy boundary of the i^th bin.

Cheers,
David