A Further Test of Internal Conversion Theory with the 88.26-keV $M$4 transition in $^{\mathrm{127m}}$Te

The 106-day isomer in $^{\mathrm{127m}}$Te decays by an 88.26-keV $M$4 transition to the ground state. We have measured the intensity of the gamma rays from this transition relative to the K x-rays, which are produced when it converts. We have also accounted for all impurities that contributed (weakly) to those intensities. Combining our result with the known K-shell fluorescence yield for tellurium of 0.875(4) yields $\alpha_{\mathrm{K}}$ $=$ 489(7) for the K-shell internal conversion coefficient (ICC). Previous ICC measurements on other $M$4 and $E$3 transitions by our group have shown that the effect of the hole created by conversion in the atomic K shell should be included in ICC calculations. Theoretical predictions for $\alpha _{\mathrm{K}}$ that account for the hole in the atomic K shell of $^{127}$Te yield 484(2), while predictions that do not include the hole yield 468(2). Our new result provides further evidence that the hole must be included in ICC calculations.