Differential energy measurement between He- and Li-like uranium intra-shell transitions

Abstract

We present the first clear identification and highly accurate measurement of the intra-shell transition $1s2p{}^3{P}_2\to 1s2s{}^3{S}_1$ of He-like uranium performed via X-ray spectroscopy. The present experiment has been conducted at the gas-jet target of the ESR storage ring in GSI (Darmstadt, Germany) where a Bragg spectrometer, with a bent germanium crystal, and a Ge(i) detector were mounted. Using the ESR deceleration capabilities, we performed a differential measurement between the $1s2p{}^3{P}_2\to 1s2s{}^3{S}_1$ He-like U transition energy, at 4510 eV, and the $1s^{2}2p{}^2{P}_{3/2}\to 1s^{2}2s{}^2{S}_{1/2}$ Li-like U transition energy, at 4460 eV. By a proper choice of the ion velocities, the X-ray energies from the He- and Li-like ions could be measured, in the laboratory frame, at the same photon energy. This allowed for a drastic reduction of the experimental systematic uncertainties, principally due to the Doppler effect, and for a comparison with the theory without the uncertainties arising from one-photon QED predictions and nuclear size corrections.

References in corpus (1)

• Doppler-tuned Bragg Spectroscopy of Excited Levels in He-Like Uranium: a discussion of the uncertainty contributions