Dear Pedro,
please see my answer inline.
I recommend you to give a look at the slides about the scoring from the last FLUKA course
https://indico.cern.ch/event/604018/contributions/2435691/attachments/1395454/2242757/08_Scoring_2017.pdf
and to eventually make use of the binary output because it will allow to compute also the statistical error by summing over several runs by means of FLUKA utility program available in $FLUPRO/flutil.
In case my comments below do not clarify your doubts, do not hesitate to contact us.
Best, luigi
On 10 Apr 2018, at 12:07, pedrojluque <pedrojluque_at_correo.ugr.es<mailto:pedrojluque_at_correo.ugr.es>> wrote:
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)?
if area is set in WHAT(6), the results is in units of cm-2 GeV-1 sr-1 per incident primary, as stated in the Note 1 of USRBDX in the manual.
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).
as expected, the result is divided by the value of WHAT(6)
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.
give a look at note 6 of USRYIELD in the manual: the angle must be specified in radiant or degree, therefore it is between 0 and 180 degrees.
The angle is computed respect to a fixed direction, usually the beam direction if not specified differently with a USRYIELD card with SDUM=BEAMDEF (note 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.
<optphot.inp>
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Received on Tue Apr 10 2018 - 22:44:39 CEST