the low core temperatures and the lack of high-temperature shells, our 20M$_\odot$ does not produce much , and (see Figure \[fig:mass\_probes\]). If we know the explosion energy within a factor of 2 (i.e. from the supernova light-curve), the yields of these isotopes from the 20M$_\odot$ star are more than an order of magnitude lower than our other progenitors. Although this study demonstrates the potential of these isotopes to probe stellar structure, detailed studies with a broader set of progenitors is needed to truly determine the range of structures we can probe with these isotopes.

![image](M15_SC47_EnergyAbus.pdf){width="0.32\linewidth"} ![image](M25_SC47_EnergyAbus.pdf){width="0.32\linewidth"} ![image](SC47_EnergyLines_Mass.pdf){width="0.32\linewidth"}

![image](M15_V48_EnergyAbus.pdf){width="0.32\linewidth"} ![image](M25_V48_EnergyAbus.pdf){width="0.32\linewidth"} ![image](V48_EnergyLines_Mass.pdf){width="0.32\linewidth"}

There are some isotopes that are primarily formed in the innermost ejecta and others are formed in shells and these isotopes can be used to differentiate our low and high mass models. For example, is primarily produced in outer shells and the hotter temperature/higher densities in our more massive models tend to produce this isotope more effectively (Figure \[fig:yield\_scexp\]). In contrast, is preferentially formed in the innermost ejecta and, because the low mass progenitors have less fallback, is produced at higher quantities in the lower mass models (Figure \[fig:yield\_vexp\]). Additionally, the production site of the radioisotopes could determine which can 