I’m an absolute beginner in FLUKA . I have to simulate a quite simple situation: a bunch of MeV électrons directed onto a small glass vial, filled with water (TARGET). I want to estimate the dose delivered to the TARGET.
Now, I’ve seen that SCORE allows to simply get the data I need but there is something I don’t understand
SCORE data are produced for every cycle: do I need to average them?
Energy Density is given in GeV/cm3 for primary particle and for a region volume of 1 cm3–> So to get the real dose in Gy I just have to
multiply the obtained value * Target volume (cm3) * Target Density (g/cm3) * 1.6E-7* Primary particles number. Is it correct?
The other point of my question concerns using USRBIN to the same extent, using the Type: REGION. 1) What is the right way to plot the energy density for all the régions?
2) Putting the same normalization value I use for SCORE, I should find the same delivered dose value, isn’t it?
Off the top of my head I am not sure there’s a precooked way to merge
SCORE outputs from various cycle .out files (more savvy flukers may want
to correct; I use this card only seldom). With a bit of patience, a minimal
script should do the trick.
If you are thinking of the output of a USRBIN scoring energy deposition on
e.g. a Cartesian grid, then yes, energy deposition is originally given in GeV/cm3/primary.
However, I think in your proposed conversion factor the dimensions are off.
On paper, starting with energy deposition in GeV/cm3/primary you divide
by the density (in g/cm3) in order to get units of dose in GeV/g/primary. You can
score dose with another USRBIN and crosscheck that the conversion is OK.
Either way, to get dose in Gy, a further multiplication by 1.602176462E-7 is
needed.
Note that, as per the FLUKA manual, the units of SCORE quantities are
per region (see the purist PS below). E.g. energy deposition would be in
GeV/region/primary. To obtain units of dose you would divide by the region
volume (to get GeV/cm3/primary) and then divide by the density (to get
GeV/g/primary). And to get dose in Gy, a further multiplication is due by
1.602176462E-7.
Now, to the other aspect of your question. If you use USRBIN to score,
say, energy on a per-region basis, you get a scalar giving the energy deposition
in GeV/region/primary… which should match the output of energy deposition with SCORE. The conversion factor above to convert to units of dose still applies.
Hopefully this is helpful. In any event, the best is to try out the different variants
to convince yourself / to bypass misunderstandings in the reply…
Cheers,
Cesc
PS: in all of the above I am assuming you have NOT entered region
volumes in the geometry declaration, as is usually the case. For
completeness, if region volumes are entered before GEOEND (see
manual), then the output of SCORE has units of “/cm3” instead of
“/region”, and the logic above should be adapted accordingly.
thanks a lot for your answer. You’re right, my conversion formula for SCORE results was wrong.
FLUKA manual reports that " (when) scoring by region the total energy density {…} results will be in GeV cm-3 per primary if volumes have been input, otherwise in GeV per region per primary." and that was misleading me because I did not enter the REGION volumes but, on the .out files I get, the energy density is nevertheless expressed in GeV/cm**3/one beam particle.
About USRBIN, I’ve found the right way (I guess) to plot the data (a 1D projection, histogram type plot).
Have a nice day.
Best,
