[fluka-discuss]: the comparision of Multiple Scattering cross section and Single Scattering cross section

From: Alberto Fasso <fasso_at_mail.cern.ch>
Date: Wed, 19 Feb 2014 15:00:03 +0100

Dear Chen Yuan,

your attachments do not help me to understand what you are trying to do.
There are several strange things.

1) the target is defined as an RPP which is not symmetric in x and y, and
is 1 um long in the z direction:
RPP tan -0.01 0.0 -0.01 0.01 0.0 0.0001
i.e.: x from -100 um to 0.0
       y from -100 um to +100 um
       z from 0.0 to 1 um
why x different from y?

2) the beam is directed along z, and is 200 um wide on both x and y
direction:
BEAM -2.E-5 0.02 0.02 ELECTRON
therefore, half of the beam (from x=0.0 to x=100 um) does not hit the
target. Why?

3) The only scoring is electron fluence in a USRBIN as follows:
200 bins in x from -100 um to 100 um
200 bins in y from -100 um to 100 um
   1 bin in z from 0.0 to 1 um
But the plot you sent looks like being in the z direction. Totally
inconsistent with the USRBIN.

4) There is a transport cutoff, but not a production cutoff.
You should have both. You can use the same limits (but remember that
production cutoffs are give by material and not by region)

5) You have attached an input for single scattering, but not one for
multiple scattering

6) With such a thin target, multiple scattering would always be switched
off automatically for single scattering, because all steps would be too
short for Moliere's theory. So, you should see no difference at all
between the two options. See at the end of output the statistics of
such switchings.

Alberto




On Tue, 18 Feb 2014, yyc2011_at_mail.ustc.edu.cn wrote:

> Dear Professor Alberto,
>
> I am very sorry for my many times asking.But,the result I got is really
> different.Please look at my attachment.In the input file,the incident
electron
> energy is 20 KeV and the carbon target is 1 um.You can see from the
figure of
> flux density;the results differ from multiple scattering to total single
> scattering.I think the difference is big,not minimal.What is your
opinion?
>
> Thanks for your guidance.Thanks for your reply.I'm very grateful to
you.
>
> Best Regards
> Chen Yuan
Received on Wed Feb 19 2014 - 16:03:59 CET