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Creators/Authors contains: "Lapierre, A"

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  1. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review A)
  2. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Research)
    We report on a method for determining the absolute nuclear charge radius of high- Z elements using extreme-ultraviolet spectroscopy of highly charged Na-like ions in tandem with highly accurate atomic structure calculations of transition energy differences. The application of this method has reduced the nuclear charge radius uncertainty of Ir 191 by a factor of 8 from the currently accepted literature value, with a recently reported charge radius of 5.435(12) fm. The result reduces the charge radius uncertainty along the full Ir isotopic chain when combined with prior optical isotope shift measurements. The technique utilizes only a few million ions stored in an ion trap, which should apply to measurements with small quantities of radioactive nuclei. Published by the American Physical Society2025 
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    Free, publicly-accessible full text available February 1, 2026
  3. ; ; ; ; ; ; ; ; (, Review of Scientific Instruments)
    We describe a method for laser-driven planar compression of crystalline hydrogen that starts with a sample of solid para-hydrogen (even-valued rotational quantum number j) having an entropy of 0.06 kB/molecule at 10 K and 2 atm, with Boltzmann constant kB. Starting with this low-entropy state, the sample is compressed using a small initial shock (<0.2 GPa), followed by a pressure ramp that approaches isentropic loading as the sample is taken to hundreds of GPa. Planar loading allows for quantitative compression measurements; the objective of our low-entropy compression is to keep the sample cold enough to characterize crystalline hydrogen toward the terapascal range. 
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    Full Text Available 
  4. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Physics B: Atomic, Molecular and Optical Physics)
    Abstract We describe a novel technique to determine absolute nuclear radii of high-Znuclides. Utilizing accurate theoretical atomic structure calculations together with precise measurements of extreme ultraviolet transitions in highly charged ions this method allows for precise determinations of absolute nuclear charge radii based upon the well-known nuclear radii of their neighboring elements. This method can work for elements without stable isotopes, and its accuracy may be competitive with current methods (electron scattering and muonic x-ray spectroscopy). 
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  5. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review A)
    Accepted Manuscript Full Text Available