RE: [fluka-discuss]: Run

From: Anton Lechner <>
Date: Sun, 30 Apr 2017 08:03:10 +0000


Even with higher electron/photon cuts, the CPU time would be rather long. You should use instead the LAM-BIAS card to reduce strongly the interaction length of photo-nuclear interactions in Tantalum. Considering the thickness of your Tantalum layer (100 um) and the cross-section for 181Ta(gamma,n) below 10 MeV, I would use a reduction factor of around 1E-5 on WHAT(2) of the LAM-BIAS card. I gave it a try with your input file, and it works fine (i.e. you can get a nice neutron spectrum with a reasonable CPU time).

From your last sentence, I guess that you are interested in the rad decay of the created 180Ta? Note that with your input file no rad decay is performed as the relevant card(s) are not issued. You have to use the RADDECAY card and related cards (depending on what you want to do). Please have a look in the manual. Just as a side remark: with the RADDECAY card you can in principle also manipulate separately the thresholds for prompt and decay radiation (but anyway, the suitable solution for improving CPU time is rather the LAM-BIAS card as mentioned above).

Cheers, Anton

From: [] on behalf of kabytayeva []
Sent: 26 April 2017 11:11
To: Fluka Discuss
Subject: [fluka-discuss]: Run

  Hello everybody!

  I would like to know is it possible to reduce the calculation time of
the number of primary histories to be simulated in the run?

I have electron beam with energy 10MeV and interested in the following
reaction: 181Ta(gamma,n)180Ta,reaction threshold is about 8.5MeV. So,
the electron's energy is low and I need in may be 10^9-10^10 number of
primary histories, but it takes a lot of CPU time. Of course, I know
that I can use EMF-CUT and it will be reduce the time of calculations,
but I notice that it cut the energy spectrum of gamma irradiation from
180Ta and I would like to see the full spectrum.

  Thank you very much!!!

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Received on Sun Apr 30 2017 - 10:03:10 CEST

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