Phase space file run issue

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Versions

Please provide the used software versions.

FLUKA:4-5.0
Flair:3.4-0

Machine: Ubuntu 20

Description

Dear experts,

In this simulation, the neutron source is read from a phase space file. While running the simulation, I observed the following aspects:

  1. No matter what the primaries are selected (1E+7 or higher), in the sum file I could see: Total primaries run: 2611280. Thus, I am unable to improve the statistics in the simulation.

  2. The simulation is finishing within 30 mins or so, however, in the Run window, large time is shown at the bottom

    Also, most of the time one or more spawn run is stopped due to Time out error.

    However, since the ‘total primaries run’ printed in the output is less than what is given in the input, I believe, it is not completing the total no of primary histories.

Can you please guide me with this issue?

Regards,

Riya

Input files

neutron_pipe.inp (9.4 KB)

source_newgen.f (20.8 KB)

fluence_neutron.zip (4.1 MB)

2

Dear Riya,

In the read_phase_space_file subroutine, you set the sequential_logical_flag to .true.. In this mode, FLUKA will read your phase-space file line-by-line and stop when it reaches it the end.

You need to set the sequential_logical_flag to .false. to sample the file randomly until you simulate the requested number of primaries.

Cheers,
David

1 Like
3

Dear @horvathd ,

I misunderstood the purpose of this logical flag, thank you for the guidance. I corrected it.

However, can you please guide why the run time is still so large? Is it purely because of the geometry considered in this case?

Regards,

Riya

4

Dear Riya,

The initial time estimation comes from the time of the first primary particle, which tends to be much longer that the later ones due to background initializations.

If you run a shorter simulation (~1e4 primaries) in the .err or .out files, you will find the correct average time per primary particle. From this you can have an accurate guess how long the full simulation would be.

Cheers,
David

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