Dear fluka users and experts ,
After the previous topic i posted :Questions about energy deposition of electron beam on tungsten target - #2 by atsingan
I started a new experiment using the same target but with low energy x-ray photons about 16kev.the problem with the usrbin number of bins remains the same .
the file im uploading has phton beam of energy 16kev.
1.i have applied x/ymin=-0.55 and x/ymax=0.55 and Nbins=11 as it was suggested in the answer of the previous topic but no plot is created .This is applied in the file i’m sending you.
2.when i apply x/ymin=-0.5,x/ymax=0.5 ,Nbins=10 it works,but the plot is not symmetrical (for the reason explained in the previous post).As it is shown below,the energy drops very quickly ,which is not strange as the energy is very low isnt it?
3.The basic reason i wanted to upload this file is that im not sure if i have used correctly the EMF-cut card ,cause i wanted to display all the particles and those of very low energy so i tried to lower the cut off energies for both photons and electrons.also activated single scattering.
4. the usryield card is not working,is there a problem with the value range ive chosen for the plot? x_Rays.flair (2.8 KB)
Thank you in advance!
Take a closer look at your EMFCUT card. There you are lowering the transport threshold to 100 eV, but only in the TARGET region! The VOID region remains untouched and therefore inherits the 100 keV transport threshold from the PRECISIO option in the DEFAULT card. This is clearly higher than your 16 keV beam energy, therefore nothing is transported, much less scored. (Note also that 1 keV is the lowest meaningful threshold for electrons/positrons, see Note 3 in the EMFCUT entry of the manual.) Fix this and you will see your scoring filling up.
Concerning the USRBINs, because the energy is low and only one bin has a non-zero value when you have 11 bins in each dimension, Gnuplot has trouble setting a color scale and gives an apparently empty plot. (This does not happen when the bin boundaries are at x=y=0 because up to 4 bins are hit.) You can check this is the case with 1D projections of the scoring. You can avoid this problem by adding bins in the z-dimension, since the 0.1 mm bins you have now are quite thick with respect to the actual penetration of the beam.
As a general comment, it is best not to put the upper energy limit of your scoring at exactly the beam energy. There is no reason to do so and might lead to ambiguous/wrong results. E.g. here you could very well use 20 keV as a safe upper limit.
Sorry, actually the EMFCUT card is not causing your apparent issues, because the VOID region is set to VACUUM, thus transport is not prevented. But it is good to be aware where you are applying thresholds, if e.g. you had air around the target, then your beam would not propagate with a 100 keV threshold. The comment on the lowest meaningful electron/positron threshold is of course valid.
The rest of the above concerning the USRBIN scorings still holds and is what is causing the apparently empty plots.
