Precise test of internal-conversion theory: α K measurements for transitions in nine nuclei spanning 45 ≤ Z ≤ 78.

We have been testing the theory used to calculate internal-conversion coefficients (ICCs) by making a series of measurements of αK values with precision better than ±2%. So far we have measured E3 transitions in three nuclei, 103 Rh, 111 Cd and 134 Cs; and M4 transitions in six nuclei, 119 Sn, 125 Te, 127 Te, 137 Ba, 193 Ir and 197 Pt. Together, these span a wide range of A and Z values. In all cases, the results strongly favor Dirac-Fock calculations in which the final-state electron wave function has been computed in an atomic field that includes the vacancy created by the internal-conversion process.