Dear Fluka experts，
I want to calculate the transmission of some substances to X-rays, my tests show that photons with energies less than about 33.5Kev will deposit at the point of entry，and it’s not about matter. But I want to test the photon energy at 1keV or even lower，Is there any way to change the minimum？
Difficult to say without seeing your input file, what you are scoring, how, in which grid, etc.
In any event, note that the recommended minimum energy for primary photons is 1 keV. The code will nevertheless allow you to transport photons down to 100 eV. See the EMFCUT card to set the photon transport threshold (and search for “Pcut” in the output file to confirm you set it correctly).
This value of 33.5 keV sounds familiar. I think it comes from using EMF without specifying precise low-energy cut-offs with EMFCUT. In this case, the program determines a cut-off automatically.
Please study the documentation of EMFCUT and set your photon cut-off to not less than 100 eV.