Precise measurements of $\alpha_{k}$ for the 346.5 keV M4 transition from $^{197}$Pt$^{m}$: A test of internal conversion theory*

Precise values for internal conversion coefficients (ICCs) are important in the study of nuclear decay schemes; they are also useful for detector efficiency calibration. A recent survey revealed that few measured ICCs are known to a high precision ($\sim $ 1{\%}); in addition, there is some theoretical uncertainty over how to deal with the atomic vacancy left by the departing electron during the internal conversion process. Texas A{\&}M has previously precisely measured the ICCs for $^{193}$Ir, $^{137}$Ba, and $^{134}$Cs as a test of internal conversion theory; we now consider the ICC for $^{197}$Pt$^{m}$ as a further test. The $^{197}$Pt$^{m }$was produced by thermal neutron activation of separated $^{196}$Pt (97.43{\%} pure). Two separate sources were produced; x-ray and gamma-ray emissions from each source were recorded by a High Purity Germanium Detector (+/- 0.20{\%} absolute efficiency uncertainty). After impurity subtraction and attenuation correction, preliminary results for the $\alpha _{k}$ value for the two sources have now been obtained. The $\alpha_{k}$ from source one is 4.24 (13); the $\alpha _{k}$ from source two is 4.26 (8). While these values are still tentative, the results show agreement with the theory that considers the atomic vacancy.