Comparison Between the (He3,Be7)α-Pickup Reactions onCa40andAr40

There have been recent suggestions, based on backward-angle anomalies of elastic $\alpha$-particle scattering, that ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ have strikingly different $\alpha$-clustering probabilities. Since a convincing body of evidence exists for the $\alpha$-pickup character of the (${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$) reaction, we investigated the reactions ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$(${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$)${}_{}{}^{36}{}_{}{}^{}\mathrm{S}$ at an incident energy of 41 MeV. No substantial difference was found between the groundstate transitions.