Investigation ofK46andCa46with (p,He3) and (p,t) Reactions at 42 MeV

The reactions ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(p,{}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{46}{}_{}{}^{}\mathrm{K}$ and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}\mathrm{}(p,t)\mathrm{}{}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ were studied simultaneously with a counter telescope at a beam energy of 41.65 MeV. Experimental resolution for the reaction products was 50 keV for tritons and 90 keV for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. Angular distributions from 20 to 60° were obtained for 12 low-lying states in ${}_{}{}^{46}{}_{}{}^{}\mathrm{K}$, for 8 of their $T=4\mathrm{}$ analogs in ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$, and for 14 lower-lying ($T=3\mathrm{}$) states in ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$. Comparison of the angular distributions with those for known final states and with distorted-wave Born-approximation calculations allowed $L$ assignments for most of the observed transitions. The combination of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}\mathrm{}(p,t)\mathrm{}{}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ (analog) and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(p,{}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{46}{}_{}{}^{}\mathrm{K}$ results helped resolve some divergent $J^{\pi }$ suggestions for ${}_{}{}^{46}{}_{}{}^{}\mathrm{K}$ found in the literature. At least three ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ca}$ levels at the location of the unnatural-parity $T=4\mathrm{}$ analog states for ${}_{}{}^{46}{}_{}{}^{}\mathrm{K}$ were excited in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}\mathrm{}(p,t)\mathrm{}$ with about 10% of the strength of the neighboring natural parity $T=4\mathrm{}$ states. This seems to indicate that the familiar one-step zero-range interpretation of ($p,t$) transfers in this case is less reliable than usual. Another unexpected result was our failure to see a strong $0^{+}$ state in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}(p,{}_{}{}^3{}_{}{}^{}\mathrm{He}){}_{}{}^{46}{}_{}{}^{}\mathrm{K}$.