--- ************************************************** 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 Il 20-02-2018 19:38 Andrea Fontana ha scritto: > Dear Beatrice, > there is an easier way to calculate the attenuation coefficient > by using the USRBDX card on BEAMPART, by scoring the particles > current thrpough a surface. You can find an example in this message > (and related thread): > > http://www.fluka.org/web_archive/earchive/new-fluka-discuss/9105.html [1] > > Regarding the second question, you need a collimated beam to use > your formula. In case of broadened beam this formula underestimates > the required thickness because photons can be scattered and you > have no control on the path lengths in the absorber. There is > a modified formula where you can include a correction factor. > You can find a discussion at this link: > > https://www.nucleonica.com/Application/Help/Helpfiles/AttenuationGammaRadiation.htm [2] > > Hope this helps. > Kind regards, > Andrea > > 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 [1]) > tel.: +39 049 8275592 [2] > 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 [1]) > tel.: +39 049 8275592 [2] > 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_mi.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 [1]) > tel.: +39 049 8275592 [2] > e-mail: > beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.pomaro_at_dicea.unipd.it><mailto:beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.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:owner-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:beatrice.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 > [1]<https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g [3] > [1]>) > tel.: +39 049 8275592 [2] > e-mail: > beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.pomaro_at_dicea.unipd.it><mailto:beatrice.pomaro_at_dicea.unipd.it<mailto:beatrice.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 [3] > FAX: +54 351 4334054 [4] > > http://www.famaf.unc.edu.ar/~valente/ [4] [5 [4]] > > ****************************************************************************************************************** > ****************************************************************************************************************** > > __________________________________________________________________________ > You can manage unsubscription from this mailing list at > https://www.fluka.org/fluka.php?id¬c_info [5] [6 [6]] > > __________________________________________________________________________ > You can manage unsubscription from this mailing list at > https://www.fluka.org/fluka.php?id¬c_info [5] [6 [6]] > > Links: > ------ > [1] > https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g [7] > [2] tel:+39%20049%20827%205592 > [3] tel:+54%20351%20433-4050 > [4] tel:+54%20351%20433-4054 > [5] http://www.famaf.unc.edu.ar/~valente/ [4] > [6] https://www.fluka.org/fluka.php?id¬c_info [6] Links: ------ [1] http://www.fluka.org/web_archive/earchive/new-fluka-discuss/9105.html [2] https://www.nucleonica.com/Application/Help/Helpfiles/AttenuationGammaRadiation.htm [3] https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&entry=gmail&source=g [4] http://www.famaf.unc.edu.ar/~valente/ [5] https://www.fluka.org/fluka.php?id¬c_info [6] https://www.fluka.org/fluka.php?id&not;c_info [7] https://maps.google.com/?q=Via+F.+Marzolo,+9+-+35131+Padova+(Italy&amp;entry=gmail&amp;source=g
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