Hydrogenic Lamb shift in iron Fe25+ and fine-structure Lamb shift

Le résumé fourni par la source

$1s\text{\ensuremath{-}}2p$ Lyman $\ensuremath{\alpha}$ transitions in hydrogenic iron ${\mathrm{Fe}}^{25+}$ have been observed from a beam-foil source in fourth-order diffraction off ADP 101 and PET 002 crystals, simultaneously with the $n=2$ to $n=4$ Balmer $\ensuremath{\beta}$ transitions diffracted in first order. Calibration of the local dispersion relation of the spectrometer using Balmer $\ensuremath{\beta}$ lines provides measurements of Lyman $\ensuremath{\alpha}$ wavelengths. The approach of fitting the full two-dimensional dispersion relation, including other members of Balmer and Lyman series, limits random and systematic correlation of parameters, and reveals a major systematic due to dynamical diffraction depth penetration into a curved crystal. The development of a theory of x-ray diffraction from mosaic crystals was necessary for the accurate interpretation of the experimental data. Photographic theory was also developed in the process of this research. Several systematics are discussed and quantified for the first time for these medium-$Z$ QED comparisons. $2s\text{\ensuremath{-}}1s$ and $4f\text{\ensuremath{-}}2p$ satellites are explicitly investigated, and a dominant systematic is uncovered, which is due to the variable location of spectral emission downstream of the beam-foil target. $1s\text{\ensuremath{-}}2{p}_{3∕2}$, $1s\text{\ensuremath{-}}2{p}_{1∕2}$ iron Lamb shifts are measured to be $35\phantom{\rule{0.2em}{0ex}}376\ifmmode\pm\else\textpm\fi{}1900\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ and $35\phantom{\rule{0.2em}{0ex}}953\ifmmode\pm\else\textpm\fi{}1800\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. These agree with but lie higher than theory. This represents a 5.7% measurement of the hydrogenic $1s\text{\ensuremath{-}}2{p}_{1∕2}$ Lamb shift in iron. The technique also reports the iron $2{p}_{3∕2}\text{\ensuremath{-}}2{p}_{1∕2}$ fine structure as $171\phantom{\rule{0.2em}{0ex}}108\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}\ifmmode\pm\else\textpm\fi{}180\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$, which represents a 51% measurement of the hydrogenic iron fine-structure Lamb shift, and reports measurements of secondary lines.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.