I am trying to save the computation time by using EMF-CUT card, and an error occurred as follows,
*** Atomic electron contribution to mcs for material 6 (CARBON) set to 0, are you sure? ***
*** if so re-enter it as 1.E-05 and run again, if not check the manual for the ***
*** EMFCUT card, PROD-CUT, what(3), execution stopped meanwhile ***
The production threshold for electrons is 1E-05=10keV, less than 100keV, why the input file can not run normally only if I set what(3)=1.0 This seeem does not conform to the FLUKA mannual about card EMF-CUT what(3).
I understand you get the error message above when you leave WHAT(3) blank in EMFCUT with SDUM=PROD-CUT. Let us know if this is not the case.
The WHAT(3) above is a dimensionless number controlling the fraction of atomic electrons effectively contributing to multiple Coulomb scattering.
As stated in the manual, WHAT(3)=1.0 (all atomic electrons contributing to multiple Coulomb scattering) is appropriate for delta-ray production thresholds of ~100 keV or larger.
Instead, in your case the delta-ray production threshold is 10 keV, so as suggested in the manual you should put a low value of WHAT(3), say 1e-5, otherwise you’d be effectively double counting the contribution of collisions with atomic electrons to the deflection: once via explicit delta-ray production, and again in multiple Coulomb scattering.
There’s no one-size-fits-all rule, but what is suggested in the manual is fair enough: one should linearly interpolate from WHAT(3)=1e-5 (for delta-ray production thresholds in the order a few keV like in your case) to 1.0 (for delta-ray production 100 keV or larger).
Yes! I got the error message when leaving WHAT(3) blank in EMF-CUT with SDUM=PROD-CUT.
Thanks for your explanation.
I have one more question: the delta ray (if E<1e-5) will immediately deposit all energy where it was produced if I set WHAT(1)=1e-5 in EMF-CUT with SDUM=PROD-CUT.
Am I right?
I have one more question: the delta ray (if E<1e-5) will immediately
deposit all energy where it was produced if I set WHAT(1)=1e-5 in EMF-CUT
with SDUM=PROD-CUT.
More or less. One states that target electrons receiving small energy transfers (which are frequent) would indeed not make it very far, so energy losses below the delta-ray production threshold are not simulated individually. Instead, they are effectively accounted for as a continuous energy loss along every charged particle step in a (non-vacuum) medium.
