2-step simulation

Dear FLUKA experts,
I am trying to perform 2-step simulation, based on the example given in this thread.
I have some questions:

  1. When I look at the created files in step 1, I see a file named “xray001_1step” that grows in size linearly when I increase the number of primaries. What is this file? In longer runs it takes a lot of storage, which is a problem when I try to run several cycles and/or spawns simultaneously.
  2. How can I concatenate the results from multiple cycles and spawns?
  3. From your experience, what is the recommended size for the phase space file? (1e6 lines? 1e7 lines?)
    Thank you kindly in advance,
    Hen Shukrun

Dear @rachel.hen.shukrun,

The file created at the end of step1 will be used as input to step2. It makes absolutely sense that increases linearly with the number of primaries. It has to be large enough to sensibly describe the population that you want to use as input in the second step. For this reason, it is not possible to answer your third question as only you can judge on this matter.

Concatenating the results is a simple concatenation of text files. For this, I would suggest to look for some guidelines on how to do this on linux, it should be straightforward.

Dear @amario,
Thank you for your replay.
The file that I am asking about is not the file used for the phase space simulation, but a binary file that I could not open (highlighted in the attached screenshot - “xray001_1step”).
As can be seen, Its size is more than 60 times larger than the size of the results file (“xray001_fort.90”).

.

I have obtained those results from a simulation of only 1000 primaries.

Thank you kindly in advance,
Hen Shukrun

Hello @rachel.hen.shukrun ,

Please provide us with your flair or input file for this simulation such that we can have a look at what triggers the creation of this large file.

Cheers,

Andreas

Dear @anwaets,
Thank you for your replay.
Please find the attached files.
Also, I wanted to ask about applying the two-step simulation process in a complex geometry.
Assuming I have the target inside a room in a building and want to simulate the particles exiting a certain wall. Should I make the area right after the wall a black body to ensure that no reflected particles are counted?

Thank you kindly in advance,
Hen
2-step_simulation_example.zip (118.6 KB)

Hello @rachel.hen.shukrun ,

From a quick glance it seems like you are using the standard mgdraw.f routine. Hence when you are calling this routine with USERDUMP specifying “step1” as SDUM, the standard output will be collected in the file with suffix “_step1” in binary format. Depending on the case you are studying this can can indeed take up quite some memory. Please have a look at for example this post on how to reduce the MGDRAW output file size.

If you would only like to count exiting particles making the surrounding geometry blackbody material is a good approach to save time. Of course it is up to your judgment if this corresponds enough to a realistic situation.

Cheers,

Andreas