I have used BIASING card for tungsten shielding. (testcylin.flair)
Using EMFCUT, the Run time for 1 cycle is around 1 hour, primaries being 5E+08.
The results still doesn’t seem okay (i.e., with large statistical errors) - (testcylin_22.bnn.lis )
The same input is repeated with BEAM = ISOTOPE (point source configuration, instead of cylindrical source). Zero output again. - (isotope.flair; [isotope.flair; isotope_emfcut.bnn.lis )
I am interested in scoring outside the shield and and also above the 1.5 mm air-gap on the top side.
Question: How to improvise on BIASING ? ( I have used 1/mu = biasing layer thickness, for 740 keV photon in Tunsgten) or, any other parameter to be added to score in the correct way ?
PFA the inputs and .lis files.
Thanking you in advance. With regards,
isotope.flair (21.1 KB)
isotope_emfcut.bnn.lis (4.0 KB)
testcylin.flair (23.3 KB)
testcylin_22.bnn.lis (4.0 KB)
Thank you for your question.
Looking at your scoring regions, some of them are defined almost entirely in
VACUUM (e.g. for your first USRBIN
DEside, the x-range seems outside your target, lying in the
VOID region, and similarly for
plgjoin1), and there is no dose deposition in
VACUUM, hence the zero values in
testcylin_22.bnn.lis for the respective scorings. So my first suggestion is to recheck your scorings.
Secondly, I see that your beam energy is set at
0.00074 GeV, and your
transport thresholds are set at
0.00073 GeV. This implies that most of the photons will immediately deposit their energy and will not travel further, i.e. they will not reach your areas of interest, hence the large statistical errors. To see the difference, I ran once with your input 2d_view.pdf (67.7 KB), and once disabling your
transport card 2D_view_no_emf_cuts.pdf (70.8 KB), thereby using the
PRECISIO defaults with thresholds at
100 keV for electrons and photons.
I recommend you to lower your particle thresholds. As to what regards the biasing, it seems correctly implemented.
Let me know if you have any other questions!
Thank you for your explanation.
Some more doubts please:
- The plot which you got, is from the USRBIN_23.bnn, right ? That is scoring ‘fluence’ over the whole geometry. I didn’t get the plot when I processed xxxx.23.bnn for me (with the set EMFCUTs) - although the primaries were 5E08. I got some error while plotting. (I understood it to be because of ‘zero’ score in some bins, hence no plot - is this correct?) Did you change any settings ?
You got the plot without EMFCUTs - with same number of primaries ? It is taking very long here for 1 cycle to finish (say, 3 h) with 5E08 primaries.
Any comment on using BEAM=ISOTOPE of my previous mail.
Thanking in advance, with regards,
I have obtained the plots I showed you via adding a
DOSE-EQ scoring in the entire geometry (i.e. not one of yours), just in order to test how secondaries will propagate with lower EMF thresholds.
Please note that the time per primary highly depends on your computing infrastructure. For the plots shown here, I have simulated 1.6E8, with 1.137E-05 s/primary for your high EMF thresholds and a larger 1.387E-04 s/primary for the low EMF thresholds, naturally as it takes more time to follow each particle to lower energies.
BEAM=ISOTOPE option, this depends on your needs. If you provide via
HI-PROBE the isotope(I see it’s
99Mo), then you are going to have all its decay products, not only the gamma line that you initially simulated.
Hope this clarifies your questions.
Thank you very much for the explanation.
How to score TID in USRBIN - I couldn’t find such a quantity ? Dose scoring fluence will not address the same thing ?
Can you please share the “usrbin” card for me to understand?
Thanking in advance, with regards,
I meant the
DOSE-EQ in my previous message. FLUKA also has the card to score
DOSE, which is the Total Iozing Dose (TID). You should decide which quantity you are interested in.
USRBIN 10. DOSE-EQ -24. 30. 35. 40.total
USRBIN -30. -35. -40. 60. 70. 80. &
Thank you very much.
I am interested to score DOSE-EQ.