[fluka-discuss]: How to reduce the statistical errors of results?

From: 梅志远 <meizhiyuan_at_hust.edu.cn>
Date: Wed, 9 Jun 2021 11:33:31 +0800 (GMT+08:00)

Dear experts,

I recently ran a simulation by Fluka. Unfortunately, I found the statistical errors of the results (the concerned particles' flux scoring by the USRTRACK cards) were very big!

I have tried many ways to reduce the errors. However, the drop of the errors are unapparent. I have some questions about the statistical errors of calculating results:

1) How many primary particles should I set in the START card to obtain a reasonable result? I have tried to set the primary particles equal to 1E8. However, the errors are still unacceptable.

2) If the number of primary particles in the START card is N, the number of cycles to run is Nr, and the number of spawned jobs is Ns, I found the number of 'total' primary particles in the result files Nt = N * Nr *Ns. So, what is the most crucial numbers influencing the statistical errors, N or Nt?

3) The Fluka manual says that the cycles of run should be 4 or 5 to obtain the statistical errors. If I run the FLUKA project by a spawning ways, the 'total' cycles of run should equal Nr * Ns. I really want to know how should I set the cycles of run to be 4 or 5. Should I directly set Nr = 4, or should I set Nr * Ns = 4? How dose the number of spawned jobs Ns affect the statistical errors?

4)Do the random number seeds in RANDOMIZ cards affect the statistical errors of the results? Should I adopt different seeds in different cycles of run to obtain a more reasonable results? If I should, how can I implement it.

I have attached my inp files here.

Any help is appreciated!

Best regards


Zhiyuan Mei
Institute of Applied Electromagnetic Engineering(IAEE)
Huazhong University of Science and Technology(HUST)
Address: Luoyu Road 1037, Wuhan, China
Tel: +86-155-2701-7168
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Received on Wed Jun 09 2021 - 07:35:11 CEST

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