Precise measurement ofK-shell fluorescence yield in iridium: An improved test of internal-conversion theory

Abstract

We have measured the total intensity of K x rays relative to 129.4-keV γ rays from decay of the second excited state in 191 Ir. This (M1 + E2) transition was observed following the β decay of 15. 4-d 191 Os. Our measured ratio yields the result α K ω K = 2.044(11). When combined with a recent measurement of the same ratio for the 80.2-keV M4 transition from 193 Ir m , this result strongly confirms the need for the K-shell hole to be included in calculations of internal-conversion coefficients α K . Since the α K value calculated for the 191 Ir transition is virtually independent of the hole treatment, our result also yields a model-independent value for the iridium fluorescence yield, ω K = 0.954(9).

Further test of internal-conversion theory with a measurement inPt197

“…Ultimately, it is this extra step that limits our precision somewhat compared with what we have achieved previously [5][6][7][8]. It is also likely that the contributions from transitions in 197 Au have misled earlier authors [15] and resulted in the apparently anomalous behavior of the α K value adopted by Raman et al [3] for the M4 transition from 197 Pt m .…”

“…We used the same experimental method and setup as in our previous measurements [5][6][7][8]. Only those details not covered in previous publications will be described here.…”

“…The question of whether or not to include the atomic vacancy was settled in 2004 by our precise measurement (±0.8%) of the K-shell conversion coefficient, α K , for the 80.2-keV M4 transition in 193 Ir [5,6] and was subsequently confirmed by our measurements of α K for the 127.5-keV E3 transition in 134 Cs and the 661.7-keV M4 transition in 137 Ba [7,8]. The impact of these results is illustrated in Fig.…”

Precise measurement ofαKandαTfor the 150.8-keVE3transition inNica1, Hardy2, Iacob3 et al. 2016Phys. Rev. CSelf Cite132150View full textAdd to dashboardCite

“…2: It includes the x-and γ-ray peaks of interest from the decay of 111m Cd, as well as a number of weak peaks from contaminant activities. In our analysis of the data, we followed the same methodology as we did with previous source measurements [1][2][3][4][5][6][7]. We first extracted areas for essentially all the x-and γ-ray peaks in the backgroundsubtracted spectrum.…”

“…Over the past decade we have published a sequence of papers [1][2][3][4][5][6][7], in which we reported measurements of K-shell Internal Conversion Coefficients (ICCs) for E3 and M 4 transitions in 6 nuclei with a precision of ±2% or better. The motivation has been to test ICC theory, in particular its treatment of the K-shell vacancy left behind by the emitted electron.…”