No data less than 0.2KeV/(μm g/cm3) when scoring LET with USRYIELD

Dear FLUKA experts,

Happy new year!

I have two questions here.

  1. I use USRYIELD to scoring the particle LET as in the attached .inp file. But the results shows that there is no data below 0.2 keV/(μm g/cm3) as shown in plot. Is there any wrong with my input or limitation setting of USRYIELD?

test_USRYIELD_38_tab.lis (297.9 KB)

  1. If I set the Nbins1 to 10000 for Particle LET from min1 0 to max1 1000, there is an error message for the data process as shown in picture of error message. Everything is normal when I set Nbins1 to 5000. Why did this happen? What should I modify if I want small resolution for scoring?

test_USRYIELD.flair (7.9 KB)
test_USRYIELD.inp (5.5 KB)

Many thanks for your help.

Kind regards,


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Hello Jingfang,

…and reciprocal happy new year wishes to you as well!

the results shows that there is no data below 0.2 keV/(μm g/cm3)

There is no contribution to the LET spectrum below some ~0.4 (keV/um) / (g/cm^3), rather, looking carefully at the horizontal axis.

You may use the DELTARAY card with option PRINT to examine stopping powers for various particles on your PMMA material, in GeV/cm. In the output tables, HEAVYION should denote your primary 12C. You’ll need to extract and plot manually, taking care of the unit conversion, which I’ve attempted by way of example in this quick plot below. Note that the kinetic energy is the total (as in not per nucleon) kinetic energy:


The low LET values you’re concerned with might come from protons: if every now and then there’s a sufficiently energetic proton around, it can easily reach the ~0.4 (keV/um) / (g/cm3) LET level. Likewise for sufficiently energetic delta rays emitted every now and then (their stopping power to be analogously accessed with the EMFFIX card).

I was not able to reproduce your second issue (for a quick run of your input file the output-file processing ran smoothly). Are you running the latest FLUKA 4-2.1?

With kind regards,


Dear @cesc ,

Thanks for your answer. It is very helpful.
Since I update the fluka to 4-2.1, there was no error message.
All problem and question are solved.

Kind regards,

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