Hi! Can I assume you are continuing on the same problem as you explained in this thread? If yes, indeed the MAT-PROP card is required to properly set the displacement damage threshold energy for the target material in the following way: WHAT(1) sets the dpa threshold in eV. Both WHAT(2) and WHAT(3) are not used. In case your target is composed of a single material which you specify as “SiGe” in your input file, both WHAT(4) and WHAT(5) can be set to “SiGe”. Then WHAT(6) sets the step size to loop over material indices, since you would be considering only one material it is not important so it can be left to its default value 1.0. The SDUM is correctly set to “DPA-ENER” since you want to set the threshold for this material.
Then indeed the proper scoring mesh needs to be implemented. The USRBIN card takes into account the minimum and maximum extent along each coordinate (Xmin, Xmax, …) and the amount of bins within these extents along each axis (Nx, Ny, Nz). The best indications to set these parameters is to look at the size and shape of your beam: you defined in your input file a divergent beam, hence in your target material you need to set the extent of the scoring mesh such that it covers the area where neutrons impact the target material. Since your target is quite small you could choose to have the USRBIN mesh to cover the entire RPP volume. The amount of bins have to be set such that after collecting sufficient statistics, when you plot the results this shows a smooth distribution of values which is properly resolved (i.e. the bins are not too large in volume such that local high dpa values are not obscured by averaging inside one bin).
Hope this is helpful,
Andreas