Defining neutron spectrum

Dear Fluka Experts,

I want to simulate a neutron source with following definition of its energy spectrum.
For energies 0 eV - 0.625 eV (Maxwell distribution)
for energies (0.625 eV- 122 keV) (as function of 1/E)
for energies (122keV - 10 Mev) - (as per crannberg watt function for fast neutrons)

How do i carry this out in the source.f? Any beginner inputs would be very welcome. I am attempting a activation calculation of SS in reactor environment.

Could anyone guide to a document on source.f that explain all the variables and its importance. An example source.f file where particles energy has been sampled from a given probability distribution function will be very much helpful and much appreciated.

Dear @mayank.rse,

I suggest using source_newgen.f instead of source.f user routine, since it is more user friendly.
In the attached file you need to look at the code starting at line 194. This is where you need to define the energy spectra - I already put the first two conditions.
In the present configuration the source is set to give kinetic energies since the flag is set .true. (look at line 252 for Energy flag).

You can find more details in the following presentation
and a very useful exercise here
2022 FLUKA.CERN course - Brussels (16-20 May 2022): Timetable · Indico (go to the last presentation of the day)

Best regards,

source_newgen.f (19.3 KB)

Thank you so much. I will try this and get back.

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