[fluka-discuss]: Fluka USRBDX scoring - comparison with mdgraw routine results

From: Andrea Celentano <andrea.celentano_at_ge.infn.it>
Date: Tue, 7 Mar 2017 12:04:28 +0100

Dear fluka users,
I am interested in sampling the current (not the flux) of muons and
muonic neutrinos passing trough a surface, perpendicular to the z-axis.
The two regions touching at the surface are called "CONCFWD" and "MUABS1".

I am interested in studying the current dependence on the particles
energy, theta angle, and position on the surface.

In my input file, I have two USRBDX cards:

First card:

USRBDX 11.0 0.01 200.0 0.2 0.0 400. &

Second card:

USRBDX 11.0 0.01 200.0 0.2 0.0 400. &

USRBDX is not giving me any position information, thus I dediced to use
the fluka user routines to manually score the current. In my mdgraw
file, the relevant lines of the BXDRAW entries are:

c This is exiting-from region
c This is entering-to region

c Check particles
       if ((REGNAME.eq.'CONCFWD').and.(REGNAME2.eq.'MUABS1')) then

"treefill" is a routine that records those variables in a ROOT TTree,
where every entry refers to a single particle crossing the surface.

I am comparing the results of the USRBDX built-in scorer with what I get
from the manual scoring. I am just focusing on the differential current
wrt the particle energy.

-> First, I process the simulation output data (using FLAIR interface)
to produce the output plot for the USRBDX scorer
-> Then, I process the ROOT TTree. I create an histogram that is equal
to the USRBDX output in terms of binning, and for each entry in the ROOT
TTree I fill this histogram with the energy, with a weight equal to
WSCRNG (but the same conclusions apply If I use WTRACK instead of WSCRNG).

I attach two plots showing the comparison for muons and for muonic
neutrinos. Fluka built-in is RED, while manual scoring is BLACK. Plots
are normalized to the number of primary particles and to the each bin width.

As you see, the two plots (built-in VS manual) are the same just in a
given energy range (low-energy for neutrinos and high-energy for muons),
while there're significant discrepancies at high energy for neutrinos
and at low energy for muons.

Am I missing something important in doing the manual scoring?

* Since I am scoring a current, I do not have to include angular factors
* Is it possible that I am missing the correct precision in writing the
numbers (especially the weights) to the ROOT TTree?
* Is there any other weight that I need to take into account?



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(image/png attachment: neutrinoComparison.png)

(image/png attachment: muonComparison.png)

Received on Tue Mar 07 2017 - 13:14:09 CET

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