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arXiv · 2101.04075

Experimental evidence of (M1+E2) mixed character of the 9.2 keV transition in $^{227}$Th and its consequence for spin-interpretation of low-lying levels

A. Kovalík·A. Kh. Inoyatov·L. L. Perevoshchikov·M. Ryšavý·. D. V. Filosofov·P. Alexa·J. Kvasil
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Abstract

The 9.2 keV nuclear transition in $^{227}$Th populated in the $\beta$-decay of $^{227}$Ac was studied by means of the internal conversion electron spectroscopy. Its multipolarity was proved to be of mixed character M1+E2 and the spectroscopic admixture parameter $\delta^2$(E2/M1)=0.695 $\pm$ 0.248 (|$\delta$(E2/M1)|=0.834 $\pm$ 0.210) was determined. Nonzero value of $\delta$(E2/M1) raises a question about the existing theoretical interpretation of low-lying levels of $^{227}$Th.

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A. Kovalík, A. Kh. Inoyatov, L. L. Perevoshchikov, M. Ryšavý, . D. V. Filosofov, P. Alexa, J. Kvasil. 2021-01-11. Experimental evidence of (M1+E2) mixed character of the 9.2 keV transition in $^{227}$Th and its consequence for spin-interpretation of low-lying levels. https://doi.org/10.1016/j.physletb.2021.136593

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