Re: [fluka-discuss]: Normalizing fluence from USRBDX

From: nikhil shetty <nikhil.nitk_at_gmail.com>
Date: Thu, 16 Jun 2016 11:27:42 +0200

*Hi there,*


*it is not trivial to get particle count from fluence as you need to know
the directions of all the particles. So you are better off by scoring
current. Then, as you have mentioned, particle count can be obtained by
multiplying the area if you have had given area value as WHAT(6) in the
USRBDX card. Look at the last few slides of the presentation available
here: www.fluka.org/content/course/NEA/lectures/Scoring.pdf*
Since USRBDX scores a double differential quantity you need to correct for
the "differentials" if you want absolute values, which is what you read in
the manual. Now to do that in the latest version of flair, add a USR-1D
plot and choose the *_tab.lis file. The first index in this file contains
values that are integrated over solid angle. If you have specified only one
detector choose the first entry in the "Det:" dropdown list which should
use the first index from the *_tab.lis file. And in the "Value:" dropdown
list, choose DX*Y, which should give you the absolute particle counts per
bin. There is some info about this kind of normalization in this thread:
http://www.fluka.org/web_archive/earchive/prova/1351.html

Cheers,
Nikhil


On Wed, Jun 15, 2016 at 6:41 PM, <mjm_at_jlab.org> wrote:

> Hello! Graduate student here trying to learn Fluka/Flair. I think I have
> a handle on the basics, and how to get Flair to plot what I want, but the
> one last hurdle I seem to have is how to turn fluence data into just
> particle count data.
>
> So reading the USRBDX entry on the online manual, I see that
> fluence/current data should be normalized by the width of the energy bin,
> and 2*pi (for one-way scoring). Taking the last step should be
> normalizing against the cm^-2 part, to go from fluence/current to just the
> number of particles detected. But I've been seeing somewhat conflicting
> information there.
>
> Does the cm^-2 represent the area of the boundary between the two regions
> that particles are travelling to/from? Or does it represent their
> tracklength (normalized by cos(theta) in the case of fluence) through an
> infinitesimally thick volume between the regions? In the case of the
> former, it should be fairly trivial to normalize, just multiply by the
> area. But if it's the latter - tracklength density - how exactly would
> you normalize that?
>
> I'm sorry if this seems like an obvious/trivial question, I've just been
> trying to figure this out for a couple weeks now, and am starting to get
> frustrated. Thanks in advance for any help!
>
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Received on Thu Jun 16 2016 - 14:09:07 CEST

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