Spectroscopy at the high-energy electron beam ion trap (SuperEBIT)

The following progress report presents some of the X-ray measurements performed during the last year on the Livermore SuperEBIT facility. The measurements include: direct observation of the spontaneous emission of the hyperfine transition in ground state hydrogenlike holmium, ¹⁶⁵Ho⁶⁶⁺; measurements of the n=2 → 2 transition energies in neonlike thorium, Th⁸⁰⁺, through lithiumlike thorium, Th⁸⁷⁺, testing the predictions of quantum electrodynamical contributions in high-Z ions down to the 0.4% level; measurements of the isotope shift of the n=2 → 2 transition energies between lithiumlike through carbonlike uranium, ²³³U^{89+⋯ 86+} and ²³⁸U^{89+⋯ 86+}, inferring the variation of the mean-square nuclear charge radius; and high-resolution measurements of the Kα radiation of heliumlike xenon, Xe⁵²⁺, using a transmission-type crystal spectrometer, resolving for the first time the 1s2p³P₁ → 1s²¹S₀ and 1s2s³S₁ → 1s²¹S₀ transitions individually. This revised version was published online in August 2006 with corrections to the Cover Date.