Reaction Ca-40(E,E'P) And Observation Of 1s Proton State

The distorted spectral function of the protons in the reaction $^{40}\\mathrm{Ca}(e, {e}^{\\ensuremath{'}}p)$ is measured. For the $2s\\ensuremath{-}1d$ region the distorted-wave impulse-approximation calculation using the Elton-Swift wave functions explains the data within 20%. The $1p$ occupation number is 1.7 times that of the shell-model prediction. After correcting for the radiative effects and for the multiple-collision background the $1s$ state is clearly observed at ${E}_{S}\\ensuremath{\\simeq}58$ MeV with a reasonable occupation number.