Oh yes! It is true that the energy variables FLUKA in the stack, TKEFLK
(NPFLKA) is always in total energy and so also the momentum.
Maybe you will obtain a better agreement if you express the mass not in
GeV/c^2 but in units of atomic mass, for instance you can write:
PMOSPR= (WHASOU(5) * AM (IONID)/AMUC12) /2.355
AMUC12 is a parameter containing 0.931... GeV/c^2
Even better if you write:
PMOSPR= (WHASOU(5) * AM (IONID)/AMUC12) /S2FWHM
S2FWHM is the 2.355 but in double precision with many more decimals
Ciao
Giuseppe
On 14/01/2022 14:45, Boscolo, Daria Dr. wrote:
> 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
>
>
--
INFN Sezione di Milano
via Celoria 16, 20133 Milano
tel: +39 02 50317307
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Received on Fri Jan 14 2022 - 16:30:30 CET