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arXiv · 1507.04668

Hyperfine anomalies in Fr: boundaries of the spherical single particle model

J. Zhang·M. Tandecki. R. Collister·S. Aubin·J. A. Behr·E. Gomez·G. Gwinner·L. A. Orozco·M. R. Pearson·G. D. Sprouse
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Abstract

We have measured the hyperfine splitting of the $7P_{1/2}$ state at the 100 ppm level in Fr isotopes ($^{206g,206m, 207, 209, 213, 221}$Fr) near the closed neutron shell ($N$ = 126 in $^{213}$Fr). The measurements in five isotopes and a nuclear isomeric state of francium, combined with previous determinations of the $7S_{1/2}$ splittings, reveal the spatial distribution of the nuclear magnetization, i.e. the Bohr-Weisskopf effect. We compare our results with a simple shell model consisting of unpaired single valence nucleons orbiting a spherical nucleus, and find good agreement over a range of neutron-deficient isotopes ($^{207-213}$Fr). Also, we find near-constant proton anomalies for several even-$ N$ isotopes. This identifies a set of Fr isotopes whose nuclear structure can be understood well enough for the extraction of weak interaction parameters from parity non-conservation studies.

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J. Zhang, M. Tandecki. R. Collister, S. Aubin, J. A. Behr, E. Gomez, G. Gwinner, L. A. Orozco, M. R. Pearson, G. D. Sprouse. 2015-07-16. Hyperfine anomalies in Fr: boundaries of the spherical single particle model. https://arxiv.org/abs/1507.04668

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