Cosmic neutron ray energy spectrum data calculation problem?

[fengfengxu]

Dear experts,

I simplified the computational model, using the air layer as the neutron source,the soil thickness is 6 m.The calculations were made using the cosmic neutron ray energy spectrum, but the resulting trend seems to be problematic.I can only calculate single-energy neutrons.

My calculations turn out to be such a trend：

The flux result trend of the relevant paper is:

How do I implement the following energy spectrum calculations?At the moment it seems that there is something wrong with the program.Please help me！

Cosmic.inp (2.9 KB)
cydnp.txt (7.2 KB)
source_spectrum.f (10.5 KB)

Fengfeng Xu
Thanks in advance！

[horvathd (Dávid Horváth)]

Dear Fengfeng,

I could not reproduce your first plot, with the user routine you provided. Also, to make it run I had to remove the first line from the spectrum file.

Furthermore, what is the quantity of the second column? For me it seems, that the numbers are the values of a lethargy plot (dN/d(logE) = E*dN/dE), while the source routine expects dN/dE values.

With my assumption I get the following source spectrum:

Which resembles the ones on your second figure.

Cheers,
David

[horvathd (Dávid Horváth)]

Dear Fengfeng,

more meaningful error messages can be found in the .out, .log and/or .err files, located next to the input file or in the fluka_xxxx directories.

In this case the problem is with the character encoding of the spectrum file. See:

Fortran runtime error( End of file) when using source.f to read a file with OPEN card

Dear Jingfang, the issue seems to be with the encoding of the file. According to my editor it is UTF-16 LE. When I change it to UTF-8, then the Fortran code can read the lines, but there are other errors in the code which prevents FLUKA to run. Cheers, David

Cheers,
David

[horvathd (Dávid Horváth)]

Dear Fengfeng,

I don’t see any changes in your spectrum file or source routine, also the attached Flair project file has different plot settings compared to the figure you posted last.

For these reasons I couldn’t reproduce you last result.

My spectrum was scored immediately after the starting location of the neutrons, so that is maybe the reason you see a different result.

Cheers,
David

[fengfengxu]

Dear Teacher David，

Dear David, your judgment is correct. I gained a lot from this exchange and thank you again.This post can be closed.

Fengfeng