Elastic scattering of protons from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow/><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>40</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow></mml:math>,<i>42</i>,<i>44</i>,<i>48</i>Ca from 20 to 50 MeV and nuclear matter radii

Differential cross sections for proton elastic scattering from $^{42}$,44,48Ca have been measured at seven energies in the laboratory energy range from 21.0 to 48.4 MeV, and for $^{40}\mathrm{Ca}$ at six energies between 25.0 and 45.0 MeV. Measurements were made at 2.5\ifmmode^\circ\else\textdegree\fi{} intervals from 10\ifmmode^\circ\else\textdegree\fi{} to 90\ifmmode^\circ\else\textdegree\fi{} (laboratory angles), and at 5.0\ifmmode^\circ\else\textdegree\fi{} intervals between 90\ifmmode^\circ\else\textdegree\fi{} and 170\ifmmode^\circ\else\textdegree\fi{}. Relative errors in the data are typically between 3% and 4%; the scale errors are also 3%. The data have been analyzed by both nonrelativistic and relativistic optical models. The optical potential parameters were used to calculate nuclear matter radius information for the calcium isotopic series, which is compared to previous results.