network to pre-collapse in order to obtain detailed end-of-life stellar abundances. These new detailed yields are used as the initial chemical abundances for the explosion nucleosynthesis scenarios.

Figure \[fig:progenitors\] shows the stellar structure of our 3 progenitors. These structures play an important role dictating the final yields of the explosion. The temperature and density in the core determine the yields in the innermost ejecta. Moving from the inner core outward, the entropy increases in all three stars. However, the entropy of the 20M$_\odot$ star rises to roughly $5\,{\rm k_B/nucleon}$ slightly before the other the 15 and 25M$_\odot$ stars. This effect can be seen in the fact that the density and temperature drops in the 20M$_\odot$ faster than even the 15M$_\odot$. This drop means that, even if the remnant masses of these stars are all the same, we expect the 20M$_\odot$ star to be less effective at making the more extreme radioactive isotopes in the innermost ejecta. As we shall see, the remnant masses are larger for the more massive progenitors, severely reducing the amount of “core” yields in the ejecta of the 20M$_\odot$ star. In addition, the temperature and density of both the 15 and 20M$_\odot$ decrease significantly with mass. 