Dear Jyoti,
you would need to perform the Fluka calculation in two steps:
- in the first step, you could save the angular distribution obtained
with USRBDX in a text file or possibly write your own MGDRAW.F
routine;
- in the second step, you need to write a specific SOURCE.F file in
which you read back the cosine directors generated in step one
and sample this distribution at each event: if you write the sampled
cosine directors in the variables TXFLK (NPFLKA), TYFLK (NPFLKA)
and TZFLK (NPFLKA), you generate a beam with the desired angular
distribution. Be careful to keep the correct normalization.
An example on how to write an user source routine can be found
in the Fluka manual in chapter 13. Further information and
examples can be found in the slides of the latest Fluka advanced
course at the link (see under "Two Step Methods"):
https://indico.cern.ch/event/489973/contributions/2148893/attachments/1271819/1884943/11_AdvancedSources2016.pdf
and in the "Two Steps" exercise:
https://indico.cern.ch/event/489973/timetable/#20160511
Hope this helps.
Kind regards,
Andrea
On 18/04/2019 07:19, Jyoti wrote:
> Dear FLUKA Experts,
>
> In USRBDX, angular distributions must be intended as distributions in
> cos (theta), where theta is the angle between the particle trajectory
> and the normal to the boundary at the point of crossing.
> Now, my intention is to transport photons according to the angular
> distribution obtained using USRBDX.
> How can I define the direction cosines of the beam in terms of the
> angle obtained from USRBDX?
>
> With Regards,
> Jyoti Garg
--
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Dr. Andrea Fontana tel: +39 0382 987991
Istituto Nazionale fax: +39 0382 423241
di Fisica Nucleare
Sezione di Pavia e-mail: andrea.fontana_at_pv.infn.it
Via Bassi 6 web : www.pv.infn.it/~fontana
27100 PAVIA, Italy
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Received on Thu Apr 18 2019 - 17:12:56 CEST