Probing $sd-pf$ cross-shell interactions via terminating configurations in $N \sim Z$ scandium isotopes*

Comparisons of terminating states based on $f_{7/2}^{n}$ and $d_{3/2}^{-1}f_{7/2}^{n+1}$ configurations in $N \approx Z$, $A \approx 40$ nuclei can provide information about two-body matrix elements that are not well-defined in current realistic forces. Specifically, effective interactions can be studied by examining these $\pi d_{3/2}^{-1}f_{7/2}$ particle-hole excitations through states that have simple structural purity. The {\it sd-pf} nuclides $^{42}_{21}$Sc$^{}_{21}$ and $^{43}_{21}$Sc$^{}_{22}$ were produced via the $\alpha pn$ and $\alpha p$ channels, respectively, in two reactions: 84-MeV $^{20}$Ne + $^{28}$Si and 94-MeV $^{24}$Mg + $^{24}$Mg. Both experiments were performed using the Gammasphere spectrometer in conjunction with the Microball charged-particle detector array. States have been observed to excitation energies of 15 MeV and higher in both nuclei, and include candidates for the terminating states of interest. Shell-model and mean-field approaches are being applied to these results.