Re: [fluka-discuss]: I: momentum spread with source routine

From: Boscolo, Daria Dr. <D.Boscolo_at_gsi.de>
Date: Fri, 14 Jan 2022 13:45:11 +0000

Hi Mario,

many thanks. I tried to test the new version but it sims to me that there is still a problem with the units.
Is it possible that while in the beam card the momentum spread has to be given in GeV/c/u (at least for heavy ions) in the source routine it is interpreted as GeV/c? When I multiply my momentum spread by the atomic mass then I get very similar results. Am I correct?


The updated user routine now looks like that:

* | Particle momentum
        CALL FLNRRN(RGAUS_MO)
         PMOSPR= (WHASOU(5) * AM (IONID)) /2.355
         PMOFLK (NPFLKA) = PBEAM + ( PMOSPR * RGAUS_MO )

* | Kinetic energy of the particle (GeV)
         TKEFLK (NPFLKA) = SQRT ( PMOFLK (NPFLKA)**2 + AM (IONID)**2 )
     & - AM (IONID)

many thanks,
Best regards,
Daria


--
Dr. Daria Boscolo
Biophysics / Biophysik
Phone / Telefon: +49 6159 71 1650
Fax: +49 6159 71 2106
Mail: d.boscolo_at_gsi.de
Location:  SB2.3.188
GSI Helmholtzzentrum für Schwerionenforschung GmbH
Planckstraße 1, 64291 Darmstadt, Germany, www.gsi.de
________________________________________
Da: Santana, Mario <msantana_at_slac.stanford.edu>
Inviato: giovedì 13 gennaio 2022 18:45:15
A: Boscolo, Daria Dr.; fluka-discuss_at_fluka.org; giuseppe.battistoni_at_mi.infn.it
Oggetto: Re: [fluka-discuss]: I: momentum spread with source routine
PMOFLK (NPFLKA) = PBEAM*(ONEONE+PMOSPR*RGAUS_MO)
-->
PMOFLK (NPFLKA) = PBEAM + ( PMOSPR * RGAUS_MO )
Isn't it?
________________________________
From: owner-fluka-discuss_at_mi.infn.it <owner-fluka-discuss_at_mi.infn.it> on behalf of Boscolo, Daria Dr. <D.Boscolo_at_gsi.de>
Sent: Thursday, January 13, 2022 3:08 AM
To: fluka-discuss_at_fluka.org <fluka-discuss_at_fluka.org>; giuseppe.battistoni_at_mi.infn.it <giuseppe.battistoni_at_mi.infn.it>
Subject: Re: [fluka-discuss]: I: momentum spread with source routine
Hi Giuseppe,
many thanks for the help.
Unfortunately, inverting the calculation of the kinetic energy and momentum did not help and I get the same result as before.
Just for consistency I attach here the new source routine and the plot with the two spectra.
Ciao,
Daria
--
Dr. Daria Boscolo
Biophysics / Biophysik
Phone / Telefon: +49 6159 71 1650
Fax: +49 6159 71 2106
Mail: d.boscolo_at_gsi.de
Location:  SB2.3.188
GSI Helmholtzzentrum für Schwerionenforschung GmbH
Planckstraße 1, 64291 Darmstadt, Germany, www.gsi.de
________________________________________
Da: Giuseppe Battistoni <giuseppe.battistoni_at_mi.infn.it>
Inviato: mercoledì 12 gennaio 2022 18:06:16
A: Boscolo, Daria Dr.; fluka-discuss_at_fluka.org
Oggetto: Re: [fluka-discuss]: I: momentum spread with source routine
Hi Daria
I see that in the source routine you write:
*  |  Kinetic energy of the particle (GeV)
          TKEFLK (NPFLKA) = SQRT ( PMOFLK (NPFLKA)**2 + AM (IONID)**2 )
      &                   - AM (IONID)
*  |  Particle momentum
          CALL FLNRRN(RGAUS_MO)
          PMOSPR=WHASOU(5)/2.355
          PMOFLK (NPFLKA) = PBEAM*(ONEONE+PMOSPR*RGAUS_MO)
*
So you first calculate the kinetic energy and after that you fluctuate
the momentum. This could be inconsistent.
Try instead to write:
*  |  Particle momentum
          CALL FLNRRN(RGAUS_MO)
          PMOSPR=WHASOU(5)/2.355
          PMOFLK (NPFLKA) = PBEAM*(ONEONE+PMOSPR*RGAUS_MO)
*  |  Kinetic energy of the particle (GeV)
          TKEFLK (NPFLKA) = SQRT ( PMOFLK (NPFLKA)**2 + AM (IONID)**2 )
      &                   - AM (IONID)
So you calculate a kinetic energy consistent with the fluctuated momentum.
I do not know if this is the solution, but I invite you to test it.
Ciao
         Giuseppe
On 12/01/2022 11:31, Boscolo, Daria Dr. wrote:
> Dear FLUKA experts,
>
> I am trying to implement a gaussian momentum spread with the source routine as it is in the beam card.
> To do that I followed the indication given in a previous discussion in this forum:
> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/18392.html
>
> However, the distribution I obtain does not match with the one I see when using the beam card: the two results differ of about a 30% on the momentum spread sigma.
>
> I attach here a plot of the two energy spectra together with the two input files and the source routine I am using.
>
> Many thanks for the help,
> Best regards,
> Daria
>
> --
> Dr. Daria Boscolo
> Biophysics / Biophysik
>
> Phone / Telefon: +49 6159 71 1650
> Fax: +49 6159 71 2106
> Mail: d.boscolo_at_gsi.de
> Location:  SB2.3.188
>
> GSI Helmholtzzentrum für Schwerionenforschung GmbH
> Planckstraße 1, 64291 Darmstadt, Germany, www.gsi.de
--
INFN Sezione di Milano
via Celoria 16, 20133 Milano
tel: +39 02 50317307
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Received on Fri Jan 14 2022 - 16:30:29 CET

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