High-precision mass measurement of doubly magic ${}^{208}$Pb

Abstract

The absolute atomic mass of ${}^{208}$Pb has been determined with a fractional uncertainty of $7\times 10^{-11}$ by measuring the cyclotron-frequency ratio $R$ of ${}^{208}$Pb${}^{41+}$ to ${}^{132}$Xe${}^{26+}$ with the high-precision Penning-trap mass spectrometer Pentatrap and computing the binding energies $E_{\text{Pb}}$ and $E_{\text{Xe}}$ 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 $9\times 10^{-12}$. $E_{\text{Pb}}$ and $E_{\text{Xe}}$ have been computed with an uncertainty of 9.1 eV and 2.1 eV, respectively, yielding $207.976650571(14)$ u (u$=9.3149410242(28)\times 10^8$ eV/c${}^2$) for the ${}^{208}$Pb neutral atomic mass. This result agrees within $1.2\sigma$ 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.

8 pages, 4 figures, to be published in EPJA

References in corpus (6)

• High-precision measurement of the atomic mass of the electron
• Direct mapping of nuclear shell effects in the heaviest elements
• TRIGA-SPEC: A setup for mass spectrometry and laser spectroscopy at the research reactor TRIGA Mainz
• The Heidelberg compact electron beam ion traps
• Mass-difference measurements on heavy nuclides with at an eV/c2 accuracy level with PENTATRAP
• Production of highly charged ions of rare species by laser-induced desorption inside an electron beam ion trap