[fluka-discuss]: Re: [fluka-discuss]: Comparisons of different methods to obtain γ-rays of Cobalt-60 in FLUKA !

From: nikhil shetty <nikhil.nitk_at_gmail.com>
Date: Thu, 1 Dec 2016 13:48:29 +0100

Hello,

Irrespective of method 1 and 2, it seems that there is a physical problem
in method 3. In reality, the two gamma rays are emitted simultaneously and
both with almost 100 % probability. The way it is implemented in method 3,
the gammas are sampled independently, however it is not true.

Well, regarding your actual question, it helps if you post the source
routines so that someone can debug them.

Cheers,
Nikhil




On Thu, Dec 1, 2016 at 11:59 AM, YANG Tao <yangt_at_ihep.ac.cn> wrote:

> Dear FLUKA users,
>
> Recently I have simulated the dose given by cobalt-60 source and I
> have some confusions. As is known, two γ-rays with energy of 1.17 MeV and
> 1.33 MeV are emitted in the decay process. To obtain the beam of two
> energies, I try to finish it in three different ways.
>
> 1. Set the BEAM card to ISOTOPE, and then define Co-60 with the HI-PROPE and
> RADDECAYcards.
>
> 2. Write a user routine to define the source, which is mainly relied on
> method by Giuseppe( *http://www.fluka.org/web_archive/earchive/new-fluka-discuss/2860.htm
> <http://www.fluka.org/web_archive/earchive/new-fluka-discuss/2860.htm>*l).
> I also declare a array titled Egamma(N) and inject two
> photons in a DO loop.
>
> 3. A similar user routine with method 2, but I don't define an array of
> photon energy, but a sampling method as follows:
>
> IF (FLRNDM(XDUMMY) .LE. 0.5) THEN
>
> TKEFLK (NPFLKA) = 0.001333
>
> ELSE
>
> TKEFLK (NPFLKA) = 0.001173
>
> END IF
> Then I compare the different results. Method 1 seems to give the
> correct results compared to the experiments. Results of method 2 and 3 are
> almost the same with each other and only about one half of the one given by
> method 1. I guess only one PHOTON/primary is emitted in method 2 and 3, so
> I define a region to wrap the Co-60 source region and score the photons
> from source using the USRBDX card, and the results confirm the guess,
> method 1 gives 2 particles/primar, while method 2 and 3 both gives 1
> particles/primary.
>
> Result of method 1 is correct since it simulates the real isotope
> decay process and emits two photons for each event by the internal
> setting of FLUKA. Method 3 emits one PHOTON each event also doesn't puzzle
> me since I use a sampling method and it selects one photon energy by the
> random number each time. However, method 2 as the explanation of Giuseppe
> will inject two PHOTONS for each event, why does it give the results like
> one PHOTON each time? I guess method 2 and 3 may indeed only emit one
> PHOTON/primary each time and I should multiply the result by 2 to obtain
> the real value, if that is the case, what is the difference of method 2 and
> 3?
>
> Any help is appreciated.
>
> T. Yang
>
> CAS
>


__________________________________________________________________________
You can manage unsubscription from this mailing list at https://www.fluka.org/fluka.php?id=acc_info
Received on Thu Dec 01 2016 - 15:33:32 CET

This archive was generated by hypermail 2.3.0 : Thu Dec 01 2016 - 15:33:34 CET