Re: [fluka-discuss]: The unit of quantity scored by MGDRAW

From: Stefan E. Mueller <stefan.mueller_at_hzdr.de>
Date: Mon, 5 Jul 2021 17:11:52 +0200 (CEST)

Dear Qi Ding,

I am not sure if this question has already been answered, but I'll try
anyway.

What you are plotting in the first plot are the positions where (p,n)
reactions take place in the y-z area (ignoring the x-coordinate). To give
this more meaning, I would dump this information into a binned
3d histogram. Then for each bin, I would have the total
(bin-integratd) number of (p,n)-reactions N(p,n) occuring in this bin with
bin widths dx, dy and dz. One can write:

N(p,n) = Integral { d3 N(p,n)/dx/dy/dz } dx dy dz

where d3 N(p,n)/dx/dy/dz is the number density in units
[Number of (p,n) reactions]/cm3

Since in every (p,n) reaction there is one neutron created, N(p,n) as
defined above also gives you the number of neutrons from (p,n)-reactions
in the corresponding bin (but there maybe also (p,2n), (p, alpha n) etc.
reactions, so this may not be the same as the total number of neutrons
produced!).

For the second plot you presented, I am not sure how you got this. Over
which quantity (or quantities) did you integrate to get to this plot? I
can't match the axis to a projection of the previous plot. Again, having
the number density as above should give you access to all the quantitites
you'd like to derive.

Integrating the number density over two coordinates (e.g. multiplying with
the corresponding bin widths) gives you something which has the unit 1/cm,
if it is exactly the quantity that you are looking for I do not know.

Cheers,

         Stefan

--
Stefan E. Mueller
Department of Information Services and Computing - Computational Science
and Institute of Radiation Physics
Helmholtz-Zentrum Dresden-Rossendorf
Tel: +49 (0351) 260 3847
Stefan.Mueller_at_hzdr.de
http://www.hzdr.de
Vorstand: Prof. Dr. Sebastian M. Schmidt, Dr. Diana Stiller
Vereinsregister: VR 1693 beim Amtsgericht Dresden
On Mon, 26 Apr 2021, Ding, Qi wrote:
> 
> Dear FLUKA experts,
> 
> 
> My simulation is a proton beam incident on a metal target(there exist water
> channels inside target).
> I want to get the information about the positions of (p,n) reactions, so I
> use a customized mgdraw (usdraw entry) user routine to record the
> coordinates(x,y,z) of positions where (p,n) reactions take place.
> 
> and I used the coordinates (y,z) to get a figure (2D distribution) which
> shows the positions where (p, n) reactions take place in y(target
> width)-z(target depth) transversal area (as shown in Fig.1). All the red
> points represent the positions where neutrons produced by (p, n). For this
> I'd like to know the unit of this quantity or event? 
> 
> And in order to evaluate neutron yield which produced by (p,n) reactions
> along target depth, I consider the number of (p,n) reactions as the amount
> of neutrons produced by (p,n). So I integrated the number of 
> 
> (p,n) reactions and get the number of reactions(neutrons) in different
> target depth (like Fig.2). For my understanding the values at y-direction
> mean the number of neutrons produced by (p,n) reactions, and the unit should
> be  [1/cm]. could you please tell me is it right?
> 
> 
> The above is my personal understanding, if there is anything wrong, please
> don't hesitate to correct me.
> 
> 
> Any comments or suggestions will be appreciated.
> 
> Best regards,
> 
> 
> Qi Ding
> 
> 
> 
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Received on Mon Jul 05 2021 - 19:11:31 CEST