Dear experts,
Is it possible in Fluka to obtain recoil energies of target nuclei from Co60 gamma interactions, in semiconductor materials such as silicon?
Even better, if this has already been done, please send me the data 
Regards, Ian
Dear @dawson,
Thank you for your question.
The main interaction of the Co60 photons (1.17 and 1.33 MeV) in the material is Compton scattering which generates secondary electrons. While most of these secondaries will continue interacting with other electrons in the material, a small percentage of them may scatter elastically with the nuclei in the material and generate recoils. Unfortunately, this interaction is not explicitly calculated for electrons in FLUKA, so the recoil energy is not available.
We can try to calculate the maximum kinetic energy of a recoil to have an idea of the order of magnitude. Assuming the maximum kinetic energy transfer in the Compton scattering, between a 1.33 MeV photon and an electron at rest, the maximum electron kinetic energy would be 961 keV, following the formula (easily derived from the Compton scattering formula available in many references):
From a kinematic perspective, the maximum kinetic energy transfer in a relativistic elastic collision between the electron and an ion at rest would be 0.15 keV following the formula (derived here):
Besides, please note that the decay of the Co60 also produces beta particles with energies 0.31 and 1.48 MeV which, depending on the application, could also play a role.
Lastly, at macroscopic level, you can estimate the impact of the photons and its secondaries in the material lattice by scoring the DPA (displacement per atom) and 1MeV neutron equivalent fluence.
I hope this helps,
Mario Sacristan Barbero