Elastic Scattering of 30.3-MeV Polarized Protons fromCa40,Fe56, andCo59

Results are presented for the elastic scattering of 30.3-MeV polarized protons from targets of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, and ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$. The angular region from 20 to 165° is covered with an absolute accuracy in the polarization measurements of about 0.01. The data, together with corresponding differential-cross-section data reported elsewhere, are analyzed using the optical model in a manner similar to that used for corresponding data for ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The present results confirm the trends with mass number found earlier, suggesting that present forms of the model are only satisfactory for large nuclei (${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$), and that for lighter systems modifications are needed.