Re: Re: [fluka-discuss]: Attenuation coefficient for photons in a material

From: Mauro Valente <mauro.valente_at_gmail.com>
Date: Tue, 20 Feb 2018 15:14:29 -0300

Dear Beatrice

Unfortunately I may not feel able for advising about FLUKA input files,
however I would contribute reminding Alberto's recommendation clearly
describing what a "transmission experiment" should be.

Do not forget setup geometric characteristics, considerations for
primary/scattering conditions: collimation for incident beam (point-like
i.e. filiform) and large enough lateral (transverse) sample dimensions.

Besides, as mentioned by Joachim, you should be clear about "type of
photons" to be detected/accounted. According to his suggestion, the
BEAMPART tally should accounts for primary photons (assuming you are
starting your simulation with photons as primary particles).

Regards,



2018-02-20 12:17 GMT-03:00 Beatrice Pomaro <beatrice.pomaro_at_dicea.unipd.it>:

> Dear Fluka experts,
> can someone check whether the attached input file is correct for the
> computation of the linear attenuation coefficient of a sample at 20cm from
> a gamma-source in a collimated geometry, please?
> BIN 42 and 43 correspond to two thin bins (2cm long in direction of the
> beam) in the front and back face of the sample, which is 10cm thick.
> I would like to know in particular if SCORE and AUXSCORE cards are
> correctly defined in the input file.
> Therefore I would compute the attenuation coefficient as: ln(BIN 43/BIN
> 42), divided by the thickness. Is it correct?
> Would you use the same procedure also for a non-collimated geometry? Or
> would you say that it is meaningless to reproduce a non-collimated
> experiment for the computation of the attenuation coefficient?
> Thank you for your attention,
> Bests
> Beatrice
>
>
> ---
> **************************************************
> Ing. Beatrice Pomaro
>
> Universita' degli Studi di Padova
> Dipartimento di Ingegneria Civile, Edile e Ambientale
> Via F. Marzolo, 9 - 35131 Padova (Italy)
> tel.: +39 049 8275592
> e-mail: beatrice.pomaro_at_dicea.unipd.it
>
>
>
> On Fri, Feb 16, 2018 at 5:49 PM, Beatrice Pomaro <
> beatrice.pomaro_at_dicea.unipd.it> wrote:
>
>> Dear Dr. Fasso',
>> thank you, I read that the score card gives a result by region of the
>> density of stars produced by the selected particles (photons in my case).
>> Does it mean that to compute the linear attenuation coefficient of the
>> medium I have to calculate this quantity with and without the absorbing
>> medium and do the natural logarithm of the ratio: ln(beampart_with
>> sample/beampart_without sample) and divide it by the thickness of the
>> sample?
>> Thank you for your explanation,
>> Best regards,
>> Beatrice
>>
>>
>>
>>
>> ---
>> **************************************************
>> Ing. Beatrice Pomaro
>>
>> Universita' degli Studi di Padova
>> Dipartimento di Ingegneria Civile, Edile e Ambientale
>> Via F. Marzolo, 9 - 35131 Padova (Italy
>> <https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g>
>> )
>> tel.: +39 049 8275592 <+39%20049%20827%205592>
>> e-mail: beatrice.pomaro_at_dicea.unipd.it
>>
>>
>>
>> Il 16-02-2018 17:03 Fasso, Alberto ha scritto:
>>
>> Dear Beatrice,
>> the easiest way to calculate the linear attenuation coefficient is to
>> score the flux of
>> primary particles (BEAMPART). This avoids the buildup due to scattered
>> particles.
>>
>> Alberto
>> ________________________________________
>> From: Beatrice Pomaro <beatrice.pomaro_at_dicea.unipd.it>
>> Sent: Thursday, February 15, 2018 4:53 PM
>> To: Fasso, Alberto
>> Cc: Mauro Valente; Vasilis Vlachoudis; fluka-discuss;
>> owner-fluka-discuss_at_mi.infn.it
>> Subject: Re: [fluka-discuss]: Attenuation coefficient for photons in a
>> material
>>
>> Ok, thank you very much Dr. Fassò. Does it mean that I have to correct
>> the computation with a buildup factor coming from literature for the
>> absorbing medium (and keep the ratio of the fluxes given by Fluka) or shall
>> I totally change the geometry of the problem?
>> Thank you,
>> Bests
>> Beatrice
>>
>>
>>
>> ---
>> **************************************************
>> Ing. Beatrice Pomaro
>>
>> Universita' degli Studi di Padova
>> Dipartimento di Ingegneria Civile, Edile e Ambientale
>> Via F. Marzolo, 9 - 35131 Padova (Italy
>> <https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g>
>> )
>> tel.: +39 049 8275592 <+39%20049%20827%205592>
>> e-mail: beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.pomaro_at_dicea.
>> unipd.it>
>>
>>
>>
>> Il 15-02-2018 16:18 Fasso, Alberto ha scritto:
>>
>> Dear Beatrice,
>> you cannot calculate a linear attenuation coefficient unless in what in
>> dosimetry
>> is called a "good geometry": both source and target being narrowly
>> collimated.
>> In the "bad geometry" that you have (no collimation) you get in addition
>> to linear
>> attenuation a buildup factor due to scattering inside the target.
>> Check on any good dosimetry textbook.
>>
>> Alberto
>> ________________________________________
>> From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi
>> .infn.it> <owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_m
>> i.infn.it>> on behalf of Beatrice Pomaro <beatrice.pomaro_at_dicea.unipd.it
>> <mailto:beatrice.pomaro_at_dicea.unipd.it>>
>> Sent: Thursday, February 15, 2018 2:30 PM
>> To: Mauro Valente
>> Cc: Vasilis Vlachoudis; fluka-discuss; owner-fluka-discuss_at_mi.infn.it
>> <mailto:owner-fluka-discuss_at_mi.infn.it>
>> Subject: Re: [fluka-discuss]: Attenuation coefficient for photons in a
>> material
>>
>> Thank you very much for your explanations,
>> so if I would like to estimate the linear attenuation coefficient through
>> the different media, am I allowed to do the natural logarithmic
>> ln(flux_in/flux_out) and divide it by the thickness, whatever the inner
>> flux is?
>> Or would you suggest a more elegant approach?
>> Thank you once more,
>> Beatrice
>>
>>
>>
>>
>> ---
>> **************************************************
>> Ing. Beatrice Pomaro
>>
>> Universita' degli Studi di Padova
>> Dipartimento di Ingegneria Civile, Edile e Ambientale
>> Via F. Marzolo, 9 - 35131 Padova (Italy
>> <https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g>
>> )
>> tel.: +39 049 8275592 <+39%20049%20827%205592>
>> e-mail: beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.pomaro_at_dicea.
>> unipd.it><mailto:beatrice.pomaro_at_dicea.unipd.it<mailto:beatr
>> ice.pomaro_at_dicea.unipd.it>>
>>
>>
>>
>> Il 14-02-2018 15:53 Mauro Valente ha scritto:
>>
>> I am not Fluka expert, but regarding the problem you pointed out, photon
>> flux might not be the same in the different situations your are studying.
>> Particularly, if you tally photon flux in the near of "entrance" surface,
>> you may count both primary and scattered photons (it may depend on the
>> FLUKA tally you used, "photon" or "beampart").
>>
>>
>>
>> changing material shall vary scattering (backscattering, for the purposes
>> of your problem, mainly) and therefore some differences could be present.
>>
>>
>>
>> If "beampart" tally does not account (please check, I am not FLUKA
>> expert) any kind of scattered particles (i.e. if you can be sure that
>> inelastic/elastic scattered primary are not accounted by beampart tally),
>> then you may compare this tally among your different setups. Otherwise, if
>> "photons" in your tally include all types of photons, you should notice
>> some differences at the entrance due to backscattering.
>>
>>
>>
>> Best regards,
>>
>> 2018-02-14 10:21 GMT-03:00 Vasilis Vlachoudis <Vasilis.Vlachoudis_at_cern.ch
>> <mailto:Vasilis.Vlachoudis_at_cern.ch><mailto:Vasilis.Vlachoudis_at_cern.ch
>> <mailto:Vasilis.Vlachoudis_at_cern.ch>>>:
>> back scattering from the material maybe?
>>
>> Cheers
>> Vasilis
>>
>>
>> ________________________________
>> From: owner-fluka-discuss_at_mi.infn.it<mailto:owner-fluka-discuss_at_mi
>> .infn.it><mailto:owner-fluka-discuss_at_mi.infn.it<mailto:owne
>> r-fluka-discuss_at_mi.infn.it>> [owner-fluka-discuss_at_mi.infn.it<mailto:
>> owner-fluka-discuss_at_mi.infn.it><mailto:owner-fluka-discuss_at_mi.infn.it
>> <mailto:owner-fluka-discuss_at_mi.infn.it>>] on behalf of Beatrice Pomaro [
>> beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.pomaro_at_dicea.unipd.it
>> ><mailto:beatrice.pomaro_at_dicea.unipd.it<mailto:b
>> eatrice.pomaro_at_dicea.unipd.it>>]
>> Sent: Wednesday, February 14, 2018 11:36
>> To: fluka-discuss
>> Subject: [fluka-discuss]: Attenuation coefficient for photons in a
>> material
>>
>>
>>
>>
>> Dear Fluka experts,
>> I am simulating an irradiation experiment with a Co60 source of samples
>> made by a different material at the same distance (20cm) from the source. I
>> have plotted the photon flux against the sample thickness, 10cm (here
>> below) and I find curiously that the flux at the face in front of the
>> source (_at_20cm) is never the same, in particular it is much different when
>> the propagation is in air (no sample).
>> Can you, please, explain me how I can fix this aspect?
>> Thank you, bests
>> Beatrice
>>
>>
>> [X]
>>
>> --
>> **************************************************
>> Ing. Beatrice Pomaro
>>
>> Universita' degli Studi di Padova
>> Dipartimento di Ingegneria Civile, Edile e Ambientale
>> Via F. Marzolo, 9 - 35131 Padova (Italy
>> <https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g>
>> <https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+
>> Padova+(Italy&entry=gmail&source=g>)
>> tel.: +39 049 8275592 <+39%20049%20827%205592>
>> e-mail: beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.pomaro_at_dicea.
>> unipd.it><mailto:beatrice.pomaro_at_dicea.unipd.it<mailto:beatr
>> ice.pomaro_at_dicea.unipd.it>>
>>
>>
>>
>>
>>
>> --
>>
>>
>> ************************************************************
>> ******************************************************
>> ************************************************************
>> ******************************************************
>>
>> Prof. Mauro Valente, PhD.
>>
>> Medical Physics
>>
>> IFEG - CONICET &
>> University of
>> Cordoba
>> Argentina
>>
>> Office 102 -
>> Laboratory 448
>> TE: +54 351 4334050 ext.
>> 102 <+54%20351%20433-4050>
>> FAX: +54 351 4334054
>> <+54%20351%20433-4054>
>>
>> http://www.famaf.un
>> c.edu.ar/~valente/
>>
>>
>> ************************************************************
>> ******************************************************
>> ************************************************************
>> ******************************************************
>>
>> ____________________________________________________________
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>>


-- 
******************************************************************************************************************
******************************************************************************************************************
                                                Prof. Mauro Valente, PhD.
                                                         Medical Physics
                                                        IFEG - CONICET &
                                                     University of Cordoba
                                                             Argentina
                                                  Office 102 - Laboratory
448
                                               TE: +54 351 4334050 ext. 102
                                                    FAX: +54 351 4334054
http://www.famaf.unc.edu.ar/~valente/
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Received on Tue Feb 20 2018 - 20:44:08 CET

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