How to determine the number of particles recorded in a phase space file and perform scoring?

Scoring
1

Dear expert, I am using a source to import a custom phase space file. This file records 200,000 photons. I want to measure the percentage depth dose (PDD) curve and profile curve in the water tank below this phase space source. I have used the usrbin-dose scorer. Do I still need to normalize the results? Will the number of photons recorded in the phase space file affect the results?

3

Dear Xing Xing,
welcome to our FLUKA community!

Yes, generally speaking, you might still need to normalize the results at different levels (e.g.: volume normalization based on the scoring mesh). I invite you to revise the FLUKA lecture on scorings.

About the second question: the number of histories has an influence on the statistical uncertainty of your results.
It is harder to predict if your phase space file is affecting the results. In fact, your implementation of the routine has an essential role in this.

  • Are you sampling from an “inventory” of photons with certain characteristics? In this case, are you sampling correctly and is the inventory sufficiently well describing your primary source? This could have a role in the physical meaning of your results.
  • Will, then, each photon be a primary particle of your simulation? One photon could be loaded on stack as primary particle, and the USRBIN scorer will contain results per primary particle.

I am sure that this lecture on Monte Carlo and this one on our FLUKA source routines contain useful hints to reach your goal. Do not hesitate to browse the forum for similar problems and to reach out here if you are still stuck.

Good luck with your simulation.
Tommaso

4

Dear Professor

Thank you for your previous responses; I have gained a clear understanding of the issue.
When I want to import two phase space files, which record particle information in different planes, does source.f support writing two phase space files? Or should I merge the two phase space files before importing?

5

Dear Xing Xing,

I would recommend to merge the two phase space files.
In my view, introducing any additional sampling logic across multiple files would be an unnecessary complication.

Best regards,

Tommaso