Energy splitting of the ground-state doublet in the nucleus 229Th.

@article{Beck2007EnergySO,
  title={Energy splitting of the ground-state doublet in the nucleus 229Th.},
  author={B. R. Beck and John A. Becker and Peter Beiersdorfer and G V Brown and Kenton J. Moody and J. Wilhelmy and Frederick S. Porter and Caroline A. Kilbourne and Richard Lloyd Kelley},
  journal={Physical review letters},
  year={2007},
  volume={98 14},
  pages={
          142501
        }
}
The energy splitting of the 229Th ground-state doublet is measured to be 7.6+/-0.5 eV, significantly greater than earlier measurements. Gamma rays produced following the alpha decay of 233U (105 muCi) were counted in the NASA/electron beam ion trap x-ray microcalorimeter spectrometer with an experimental energy resolution of 26 eV (FWHM). A difference technique was applied to the gamma-ray decay of the 71.82 keV level that populates both members of the doublet. A positive correction amounting… 
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