Hello
maybe there is a problem of naming convention.
the polar angle is the angle between the direction of the particle and the
direction of the beam. If the particle is emitted in the forward direction
along the beam axis, it has zero polar angle. If emitted in a direction
perprndicular to the beam, it has 90 degrees (pi) angle. Uf totally
backward--> 180 degrees or 2pi.
The 4pi is the total solid angle, where the additional 2pi comes from the
integration on the azimuthal angle, the one measured in the plane
perpendicular to the beam.
Hope this helps
Paola
> Dear FLUKA experts,I want to obtain the photon yield around a Cu target
> shot by an electron beam. I'd like to plot the yield with an angular
> distribution. So I use the USRYIELD card.
>
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> I indeed get a plot as shown below. But I'm puzzled about the definition
> of the polar angle, namely the X axis of the plot.
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> (1) Yes, I know the Upper limit of the polar angle is forced to π, why?
> why not the natural upper limit of polar angle, 2π? In my opinion, the
> maximal polar angle should be 2π to cover the full angular distribution.
> For a polar angle of π, only half the angular distribution is obtained.
> Maybe it works for usual Symmetric simulations. BUT for an asymmetrical
> yield angular distribution, it cannot work. Did I get a wrong
> understanding?
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> (2) How can I associate the X asis (namely the polar angle) to the solid
> angle in sr?
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> Any help is appreciate!
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> Best regards!
>
> Zhiyuan
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> --
>
>
> Zhiyuan Mei
> meizhiyuan_at_hust.edu.cn
>
>
> /---------------------------------------------------
> Institute of Applied Electromagnetic Engineering(IAEE)
> Huazhong University of Science and Technology(HUST)
> Address: Luoyu Road 1037, Wuhan, China
> Tel: +86-155-2701-7168
> /---------------------------------------------------
>
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>
Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148
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Received on Tue Oct 13 2020 - 11:26:40 CEST