Comparison of muonic-atom and electronic x-ray isotope shifts in lead

Abstract

New measurements by Lee and Boehm of electronic x-ray isotope shifts in lead substantially reduce, but do not eliminate, the discrepancy between electronic x-ray and muonic isotope shifts in this element. For the isotope pairs $^{208\ensuremath{-}207}\mathrm{Pb}$ and $^{206\ensuremath{-}204}\mathrm{Pb}$, we confirm the conclusion of Lee and Boehm that electronic and muonic data are now consistent. For the isotope pair $^{208\ensuremath{-}206}\mathrm{Pb}$, the reported electronic x-ray shift is less by at least 22% (2 standard deviations) than what would be expected on the basis of the muonic data. Internal inconsistencies in the muonic data for this pair of isotopes can be removed by postulating a nuclear resonance that pushes the $2{p}_{\frac{3}{2}}$ state up by 0.3 keV or the $2{p}_{\frac{1}{2}}$ state down by 0.3 keV. For the isotope pair $^{208\ensuremath{-}204}\mathrm{Pb}$, the discrepancy between electronic and muonic data is in the same direction as for $^{208\ensuremath{-}206}\mathrm{Pb}$, but it is somewhat smaller and may not be significant.[NUCLEAR STRUCTURE $^{208,\phantom{\rule{0ex}{0ex}}207,\phantom{\rule{0ex}{0ex}}206,\phantom{\rule{0ex}{0ex}}204}\mathrm{Pb}$; analyzed muonic isotope shifts, compared electronic shifts.]