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Free keywords:
Nuclear Experiment, nucl-ex, Physics, Atomic Physics, physics.atom-ph
MPINP:
Research group Z. Harman – Division C. H. Keitel
MPINP:
Präzisionsexperimente - Abteilung Blaum
MPINP:
Expt. PENTATRAP - Abteilung Blaum
Abstract:
The absolute atomic mass of 208Pb has been determined with a fractional uncertainty of 7 × 10−11 by measuring the cyclotron-frequency ratio R of 208Pb41+ to 132Xe26+ with the high-precision Penning-trap mass spectrometer Pentatrap and computing the binding energies EPb and EXe of the missing 41 and 26 atomic electrons, respectively, with the ab initio fully relativistic multi-configuration Dirac–Hartree–Fock (MCDHF) method. R has been measured with a relative precision of 9 × 10−12 . EPb and EXe have been computed with an uncertainty of 9.1 eV and 2.1 eV, respectively, yielding 207.976 650 571(14) u (u = 9.314 941 024 2(28) × 108 eV/c2 ) for the 208 Pb neutral atomic mass. This result agrees within 1.2σ with that from the Atomic-Mass Evaluation (AME) 2020, while improving the precision by almost two orders of magnitude. The new mass value directly improves the mass precision of 14 nuclides in the region of Z = 81–84 and is the most precise mass value with A > 200. Thus, the measurement establishes a new region of reference mass values which can be used e.g. for precision mass determination of transuranium nuclides, including the superheavies.
