Re: Re: [fluka-discuss]: Problem simulating radioactive decay of isotopes at rest

From: emilio <emilio_at_impcas.ac.cn>
Date: Fri, 22 Jul 2022 19:23:16 +0800 (GMT+08:00)

Dear Paola,

thank you very much for your answer.

I tried using USRBDX, and it works.

However... I cannot see any particle coming out....

My guess is that the radioactive decay never take place: I tried to replace ISOTOPES with ELECTRON, and I can actually see the particles, so it's not a problem of USRBDX...

I only included the RADDECAY card, selecting the "semi-analogue" mode and leaving everything else empty; from my understanding this should be sufficient to have radioactive decay (without cards such as IRRPROFI or DCYTIMES, etc...), is it correct?

RADDECAY 2. 0.0

In the attached files you can find the input card and an example of the output

Thank you again for your help
Best Regards,
Emilio


&gt; -----Original Messages-----
&gt; From: "Paola Sala" <paola.sala_at_mi.infn.it>
&gt; Sent Time: 2022-07-21 17:22:37 (Thursday)
&gt; To: emilio <emilio_at_impcas.ac.cn>, fluka-discuss_at_fluka.org
&gt; Cc:
&gt; Subject: Re: [fluka-discuss]: Problem simulating radioactive decay of isotopes at rest
&gt;
&gt; Dear Emilio,
&gt;
&gt; The problem is in the combination of an ISOTOPE beam with the USRYIELD
&gt; cards.&nbsp; USRYIELD calculates angular quantities with respect to the
&gt; direction of the beam, and since some of the quantities can be
&gt; calculated with respect to the center-of-mass frame, the code tries to
&gt; initialize a center-of-mass momentum, which fails if the beam momentum
&gt; is zero.
&gt;
&gt; I have a question and a solution, besides that this specific situation
&gt; will be
&gt; protected in a next respin
&gt;
&gt; Question: are you sure that you need USRYIELD instead of USRBDX? I
&gt; mean, what is the purpose of calculating angles with respect to a
&gt; fixed (beam) direction when source and geometry are perfectly
&gt; isotropic? Why not to use USRBDX that calculates angles with respect
&gt; to the normal to the boundary surface? (see note 1 to the USRYIELD
&gt; description in the manual)
&gt;
&gt; Solution, in case you really need USRYIELD: add another USRYIELD card
&gt; with SDUM=BEAMDEF (see again note 1) , in order to define a dummy beam
&gt; just to initialize the scoring. For instance
&gt; USRYIELD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; PROTON&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1.0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 1.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0. 1.0 BEAMDEF
&gt;
&gt; Again from the fluka manual, USRYIELD description:
&gt; For SDUM = BEAMDEF:
&gt; &nbsp;&nbsp;&nbsp;&nbsp; WHAT(1) = projectile particle index, or corresponding name
&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Default= IJBEAM (beam particle)
&gt; &nbsp;&nbsp; &nbsp; WHAT(2)= target particle index, or corresponding name (used by the
&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; code to define the c.m.s. frame)
&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Default : 1.0 (proton)
&gt; &nbsp;&nbsp;&nbsp;&nbsp; WHAT(3) = projectile momentum
&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Default= PBEAM (beam momentum)
&gt; &nbsp;&nbsp;&nbsp;&nbsp; WHAT(4,5,6) = projectile direction cosines
&gt; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Default = UBEAM, VBEAM, WBEAM (beam direction cosines)
&gt;
&gt; Hope this helps
&gt; Paola
&gt;
&gt; On 7/21/22 06:44, emilio wrote:
&gt; &gt;
&gt; &gt; Dear Fluka experts,
&gt; &gt;
&gt; &gt;
&gt; &gt; I am trying to simulate the decay of radioactive isotopes, however
&gt; &gt; when I try to run the got (via Flair), i got a time-out error and no
&gt; &gt; output is produced.
&gt; &gt;
&gt; &gt;
&gt; &gt; In the attached file you can find the input card; I do believe however
&gt; &gt; that the issue is in the primary particle generation.
&gt; &gt;
&gt; &gt; The radioactive isotopes are created with the following BEAM card
&gt; &gt; (which is similar to the one I found here:
&gt; &gt; https://indico.cern.ch/event/604018/contributions/2435668/attachments/1395470/2242783/19_Activation_2017.pdf)
&gt; &gt;
&gt; &gt;
&gt; &gt; BEAM ISOTOPE
&gt; &gt; HI-PROPE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 34.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 83.
&gt; &gt;
&gt; &gt;
&gt; &gt; The RADDECAY card is present as well (semi-analogue mode)
&gt; &gt;
&gt; &gt;
&gt; &gt; At first I thought the problem was that the isotopes are created at
&gt; &gt; rest, so I changed the energy to 1 keV, but I got the same result.
&gt; &gt; However if I try to change particle (for example, using electrons) the
&gt; &gt; code runs without problem.
&gt; &gt;
&gt; &gt;
&gt; &gt; Any idea where could be the issue?
&gt; &gt;
&gt; &gt; Thank you very much for your help
&gt; &gt;
&gt; &gt; Best Regards
&gt; &gt;
&gt; &gt; Emilio Ciuffoli
&gt; &gt;
&gt; &gt;
&gt; &gt;
&gt; &gt;
&gt;
&gt; __________________________________________________________________________
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</emilio_at_impcas.ac.cn></paola.sala_at_mi.infn.it>


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Received on Fri Jul 22 2022 - 15:10:06 CEST

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