[fluka-discuss]: Interpretation of USRBDX and USRYIELD cards

From: pedrojluque <pedrojluque_at_correo.ugr.es>
Date: Tue, 10 Apr 2018 12:07:19 +0200

Dear fluka users,

I am having lots of problem when scoring the number of particles (in
this case optical photons) that crosses and area. The goal of my code is
to count the number of optical photons detected by a photomultiplier.

First of all, I use the USRBDX which, as I have read, can give me an
stimation of the number of particles that cross a certain area (in units
of fluence or flow). Now, the first thing I am not sure about is: If I
specify the crossed area in this card, will I obtain the number of
particles that cross that area (per GeV and primary) or the number of
particles that cross the area per cm^-2 (per GeV and primary)?

Because, when I use the area, the result is only the result obtained
without specifying the area divided by this area (And the same using
USRTRACK).

My second question arises when using the USRYIELD card: As you can see
in my input file, I try to calculate the differential yield in energy
and polar angle in order to obtain the yield (I expect, dividing the
obtained yield by the muon energy, a value of 24000 photons generated
per MeV of the muon).

However, when I use polar angle in degrees and polar angle in radians
(to cover the same angle, 360º = 4pi radians) I obtain values with 3
order of magnitude of difference (using radians 3.1395E+14, using
degrees 4.5384E+17). How is this possible? I also tried to use 180º to
see what happen, and again I became surprised because the value now is
3.4562E+11 photons GeV^-1rad^-1.

Finally, I scored the energy deposited by the muon, and I took a
correct value for a MIT particle (around 2 MeV/cm), so I assume the
parameters of the simulation are correct, and the problem comes from a
misanderstanding of the USRYIELD and USRBDX outputs.

Can someone help me to understand these values?

King regards,

Pedro.



__________________________________________________________________________
You can manage unsubscription from this mailing list at https://www.fluka.org/fluka.php?id=acc_info

Received on Tue Apr 10 2018 - 13:46:34 CEST

This archive was generated by hypermail 2.3.0 : Tue Apr 10 2018 - 13:46:35 CEST