and the initial abundances (magenta) for our 15 solar mass progenitor. The dashed verticle lines mark the edge of the iron core and the boundary between the C/O core and He burning layer (see figure \[fig:progenitors\]). is produced in both the inner ejecta and an outer shell.[]{data-label="fig:exampleenergy2"}](M15_CR51_EnergyAbus.pdf){width="\linewidth"}

Another issue arises from the fact that many of the isotopes can be produced both in the inner ejecta (we refer to this site as the “core” site) and in shell burning layers that lie further out (“shell” sites) and the dominant production site can vary depending both on the progenitor structure and the explosion properties. For example, is produced both in the innermost ejecta (Si layer and O burning layer) as well as the helium-burning layer, with a dominant contribution of the explosive component compared to the pre-supernova production (see Figure \[fig:exampleenergy2\]). Indeed, with the exception of , the production of all the other radioactive species discussed in this work is dominated by the SN explosion. Depending on the isotope and on the model, a relative different contribution is obtained from explosive Si-burning, O-burning, C-burning or He-burning. The relative contributions these different layers for some isotopes depends one the explosion energy (Figure 