Laser spectroscopy of francium isotopes at the borders of the region of reflection asymmetry

I. Budinčević, J. Billowes, M. L. Bissell, T. E. Cocolios, R. P. De Groote, S. De Schepper, V. N. Fedosseev, K. T. Flanagan, S. Franchoo, R. F. Garcia Ruiz, H. Heylen, K. M. Lynch, B. A. Marsh, G. Neyens, T. J. Procter, R. E. Rossel, S. Rothe, I. Strashnov, H. H. Stroke, K. D.A. Wendt

    Research output: Contribution to journalArticlepeer-review


    The magnetic dipole moments and changes in mean-square charge radii of the neutron-rich 218m,219,229,231Fr isotopes were measured with the newly installed Collinear Resonance Ionization Spectroscopy (CRIS) beam line at the On-Line Isotope Mass Separator (ISOLDE), CERN, probing the 7s2S1/2 to 8p2P3/2 atomic transition. The δr2A,221 values for 218m,219Fr and 229,231Fr follow the observed increasing slope of the charge radii beyond N=126. The charge radii odd-even staggering in this neutron-rich region is discussed, showing that 220Fr has a weakly inverted odd-even staggering while 228Fr has normal staggering. This suggests that both isotopes reside at the borders of a region of inverted staggering, which has been associated with reflection-asymmetric shapes. The g(219Fr)=+0.69(1) value supports a π1h9/2 shell-model configuration for the ground state. The g(229,231Fr) values support the tentative Iπ(229,231Fr)=(1/ 2+) spin and point to a πs1/2-1 intruder ground-state configuration.

    Original languageEnglish (US)
    Article number014317
    JournalPhysical Review C - Nuclear Physics
    Issue number1
    StatePublished - Jul 23 2014

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics


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