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

Abstract

The reactions $^{48}\mathrm{Ca}(p,^{3}\mathrm{He})^{46}\mathrm{K}$ and $^{48}\mathrm{Ca}(p,t)^{46}\mathrm{Ca}$ 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\ifmmode^\circ\else\textdegree\fi{} were obtained for 12 low-lying states in $^{46}\mathrm{K}$, for 8 of their $T=4$ analogs in $^{46}\mathrm{Ca}$, and for 14 lower-lying ($T=3$) 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 $^{48}\mathrm{Ca}(p,t)^{46}\mathrm{Ca}$ (analog) and $^{48}\mathrm{Ca}(p,^{3}\mathrm{He})^{46}\mathrm{K}$ results helped resolve some divergent ${J}^{\ensuremath{\pi}}$ suggestions for $^{46}\mathrm{K}$ found in the literature. At least three $^{46}\mathrm{Ca}$ levels at the location of the unnatural-parity $T=4$ analog states for $^{46}\mathrm{K}$ were excited in $^{48}\mathrm{Ca}(p,t)$ with about 10% of the strength of the neighboring natural parity $T=4$ 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 $^{48}\mathrm{Ca}(p,^{3}\mathrm{He})^{46}\mathrm{K}$.