Re: [fluka-discuss]: Number of primaries when using source.f

From: <me_at_marychin.org>
Date: Sun, 2 Aug 2015 22:38:38 -0700 (PDT)

Dear Hamideh,

First thing to check is whether your the energy in your second column
(photon/s/energy) is the energy (E), or the difference in energy or the bin
width (dE). Both would have the same dimension and unit. The latter is typically
used for histograms with logarithmic bins, as in lethargy plots. For the latter
case, one would multiply with the corresponding bin width to get the count for
each bin.

Getting the above right is important for sampling the energy correctly in
source.f, and also for understanding how many photons are there per second.

:) mary


> On 02 August 2015 at 08:22 Hamideh Jalali <jalali.hb_at_gmail.com> wrote:
>
>
> Dear FLUKA users
>
>
> We know the fluka results (fluence, dose, deposited energy and ...) are
> reported per primary particle, so we should multiply the fluka results by the
> number of primary particles to get the final value of our desired quantities.
> For example when we have an electron beam with a certain current, the number
> of primaries is determined by the current of beam
> (electron/second).
> In my case I have a number of photons which have different energies. In other
> word, in my FLUX.dat file there are two columns, first column is energy(E) and
> second is photon/s/energy(F). I used this file to program a source.f.
> Maybe there is a kind of misunderstanding with me about the calculation of
> the number of whole photons or primaries per second. I think, to get the
> whole number of photons I should multiply the second column in dat
> file(photon/sec/energy) by first column (energy). Then sum up all photon/s to
> find the final number of primaries per second. The fluka results should be
> multiplied by this number to get my desired quantity(dose equivalent rate in
> my problem).
> But by using this way, my final results are much more than expected values.
>
> There are some other methods to calculate the number of primaries:
> Sigma( (Ei+1 - Ei) * Fi )
>
> Sigma( (Ei + Ei+1) / 2) * Fi)
>
> Sigma ( (Ei+1 - Ei) *( Fi+1 + Fi))
>
> Sigma( (Ei + Ei+1) / 2) * (Fi + Fi+1))
>
> Could you please guide me which one is correct?
> I hope I could have explained clearly what I mean.
>
> Kind Regards
> Hamideh
>



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Received on Mon Aug 03 2015 - 09:12:42 CEST

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