[fluka-discuss]: RE: What (1) parameter of BEAM

From: Vasilis Vlachoudis <Vasilis.Vlachoudis_at_cern.ch>
Date: Tue, 1 Apr 2014 07:53:36 +0000

Hi Helmut,

cross sections are initialized with a fixed width grid.
The variable binning mostly applies to EMF, dE/dx, DPA, delta-rays and some atomic processes
The process of readjusting the binning is somehow complex, therefore
I don't see any easy way to demonstrate with an example.


From: Helmut Vincke
Sent: 27 March 2014 09:48
To: Vasilis Vlachoudis; fluka-discuss (fluka-discuss_at_fluka.org)
Subject: RE: What (1) parameter of BEAM

Dear Vasilis

Thanks for your answer. I still have some doubts in that matter and would like to address them with an example. In particular, your statement that the tabulation becomes coarser when using a higher threshold.
I have a source routine which samples starting particles from thermal energies up to 100 TeV. When I set now the WHAT(1) of the beam card to 100 TeV does it cause then a tabulation binning being too coarse in the low-energy range (e.g. 100 MeV)? My interest in that matter (tabulation of cross sections) goes primarily to activation of matter.
Thanks again for the re-iteration of the problem.

Best regards

From: Vasilis Vlachoudis
Sent: 27 March 2014 09:08
To: Helmut Vincke; fluka-discuss (fluka-discuss_at_fluka.org)
Subject: RE: What (1) parameter of BEAM

Hi Helmut,

you correctly guessed. All tabulations of cross sections, dE/dx, etc... are calculated from the minimum threshold defined in your
input and/or from the DEFAULTS up to the energy defined in the BEAM what(1) + 10% (if I remember well).
So if you put a lower value than your source.f routine, you will make the code crashing most probably with a dp/dx < 0 (negative!)
If you set it too high you will get both unnecessary tabulations, longer initialization time and more coarser.

dE/dx tabulations you can control and print them with the EMFFIX, FLUKAFIX

Best Regards
Vasilis Vlachoudis
CH-1211 GENEVA 23

Phone: +41-22 767 9851
GSM: +41-76 487 4378
Fax: +41-22 766 9644
From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi.infn.it> [owner-fluka-discuss_at_mi.infn.it] on behalf of Helmut Vincke [Helmut.Vincke_at_cern.ch]
Sent: 26 March 2014 17:46
To: fluka-discuss (fluka-discuss_at_fluka.org<mailto:fluka-discuss_at_fluka.org>)
Subject: [fluka-discuss]: What (1) parameter of BEAM
Dear FLUKA users and authors

Can someone provide me with a bit more information about the mandatory need of WHAT(1) of the BEAM card (in case I sample my primary particles via a source.f routine). The manual says:

(command BEAM<http://www.fluka.org/fluka.php?id=man_onl&sub=12> not requested): not allowed! The WHAT(1) value of the

              BEAM<http://www.fluka.org/fluka.php?id=man_onl&sub=12> command is imperatively required, in order to set up the

              maximum energy of cross-section tabulations.

What kind of cross sections are tabulated and how does it refer to the energy/momentum set in WHAT(1)?

Is it a problem for the accuracy of the run when setting the WHAT(1) to 100 TeV and sampling primary particles only in the GeV range? I would be grateful if you could give me some indications if the granularity of the cross-section tabulation is a function of the WHAT(1) parameter or if a higher WHAT(1) value just increases the number of cross sections tabulated for the run.
Thanks in advance.

Best regards
Received on Tue Apr 01 2014 - 11:08:04 CEST

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