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

Highlights: • Precise K-shell internal conversion coefficients measured for 9 E3 and M4 transitions. • Measurements made with HPGe detector precisely calibrated for efficiency. • Results agree with calculations that include provision for the atomic vacancy; and disagree with those that do not. • Wide range of Z and A values covered, indicating broad applicability of this outcome. - Abstract: We have been testing the theory used to calculate internal-conversion coefficients (ICCs) by making a series of measurements of α_K values with precision better than ±2%. So far we have measured E3 transitions in three nuclei, ¹⁰³Rh, ¹¹¹Cd and ¹³⁴Cs; and M4 transitions in six nuclei, ¹¹⁹Sn, ¹²⁵Te, ¹²⁷Te, ¹³⁷Ba, ¹⁹³Ir and ¹⁹⁷Pt. 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.