Coincident measurements on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ of $\mathrm{KLL}$ Auger electrons and backscattered protons at 125° show that the $K$-shell ionization probability varies over the 461-keV $s$-wave resonance. The data are explained through a change in the phase shifts for simultaneous ionization and scattering, due to the dipole ionization amplitude.

• Received 4 August 1980

DOI:https://doi.org/10.1103/PhysRevLett.45.2102