Re: [fluka-discuss]: The use of EMFCUT

From: Paola Sala <paola.sala_at_mi.infn.it>
Date: Wed, 1 Jan 2014 16:11:48 +0100

Dear Chen Yuan,

Indeed, I would expect an higher electron flux on the target side, that is
what you have. The target (10 microns carbon) is not thick enough to stop
the 60 KeV electrons. On the contrary, it is thick enough to allow for the
production of secondary electrons that increase the total electron flux
(buildup). This is a very well known behaviour in radiation transport.
You can see it in the attached plot, where I took your input and extended
the target in the z direction. The plot shows the electron flux as a
function of z and x, you can clearly see the initial buildup followed by
decrease. (I had small statistics, small color variations are due to
statistics).

About the two spikes in your plot, at the left and right of the target
boundary, I'm not completely sure but they might be due to the fact that
scattered and secondary electrons can only go from the target to the
vacuum, not vice-versa, thus creating a depletion zone on the target side
and an overpopulation on the vacuum side.

You also sent me another mail, about the what(60 in MULSOPT. Above 1000 it
has no influence, therefore it cannot influence the CPU time.

Regards
Paola

> Dear everyone,
>
> The attachment is my input file and the figure of flux density.In the
> input file,the primary energy of electron is 0.06MeV.The thickness of
> carbon target is 10um.The electron transport cutoff energy I set is
> 1KeV.
> However,the figure of flux density I got is odd. The flux density on the
> left side of the border is larger than the flux density on the right
> side of the border.You know,the 10um carbon target is located on the
> left side.In theory,the flux density on the left side of the border
> should be less than the flux density on the right side of the border.
> So,I doubt the EMFCUT card I set is wrong.Could you have a look at my
> input file?Is there any wrong about the EMFCUT card I set?
>
> Best Regards
> Chen Yuan
>
>
>
>
>
>
>


Paola Sala
INFN Milano
tel. Milano +39-0250317374
tel. CERN +41-227679148



Received on Wed Jan 01 2014 - 17:19:12 CET

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