Test Of Bound-state QED Research Articles

First observation of the ground-state hyperfine transition in 209Bi80+

The long sought after ground-state hyperfine transition in lithium-like bismuth 209Bi80+ was observed for the first time using laser spectroscopy on relativistic ions in the experimental storage ring at the GSI Helmholtz Centre in Darmstadt. Combined with the transition in the corresponding hydrogen-like ion 209Bi82+, it will allow extraction of the specific difference between the two transitions that is unaffected by the magnetic moment distribution in the nucleus and can therefore provide a better test of bound-state QED in extremely strong magnetic fields.

Study of hyperfine structure in simple atoms and precision tests of the bound state QED

We consider the most accurate tests of bound state QED, precision theory of simple atoms, related to the hyperfine splitting in light hydrogen-like atoms. We discuss the HFS interval of the 1 s state in muonium and positronium and of the 2 s state in hydrogen, deuterium and helium-3 ion. We summarize their QED theory and pay attention to involved effects of strong interactions. We also consider recent optical measurements of the 2 s HFS interval in hydrogen and deuterium.

A status report on experimental tests of QED in medium- Z systems

The electron beam ion trap has opened the door for experimental physics to perform critical tests of bound state QED in the medium- Z regime. The relatively small uncertainties associated with the theoretical predictions necessitate highly accurate experimental measurements of atomic transition energies. This work presents an overview of the issues and key concepts involved in the field. It also demonstrates several major steps taken to suppress systematic uncertainties that have limited past work and presents an error budget for current and future work.

Proton Zemach radius from measurements of the hyperfine splitting of hydrogen and muonic hydrogen

While measurements of the hyperfine structure of hydrogen-like atoms are traditionally regarded as test of bound-state QED, we assume that theoretical QED predictions are accurate and discuss the information about the electromagnetic structure of protons that could be extracted from the experimental values of the ground state hyperfine splitting in hydrogen and muonic hydrogen. Using recent theoretical results on the proton polarizability effects and the experimental hydrogen hyperfine splitting we obtain for the Zemach radius of the proton the value 1.040(16) fm. We compare it to the various theoretical estimates the uncertainty of which is shown to be larger that 0.016 fm. This point of view gives quite convincing arguments in support of projects to measure the hyperfine splitting of muonic hydrogen.

Density shift and broadening of transition lines in antiprotonic helium

The density shift and broadening of the transition lines of antiprotonic helium have been evaluated in the impact approximation using an interatomic potential calculated ab initio with the symmetry-adapted perturbation theory. The results help to remove an uncertainty of up to 10 ppm in the laser spectroscopy data on antiprotonic helium and are of importance in experimental tests of bound state QED and CPT invariance.

Measurement of the gj factor of hydrogenic ions: a sensitive test of bound state QED

Thegj factor measurement of hydrogenic ions in the 1s ground state is with an expected accuracy of 10−7 a sensitive test of bound state QED. We expect to determine the deviations from the free electron value, caused by relativistic and radiative corrections, up to the orderα/4π(Zα)2 with an accuracy of 1%. As a first step, light ions like C5+ will be investigated. Later on, heavier hydrogenic ions up to U91+ will be examined using the accelerator facilities at GSI in Darmstadt.

The gj factor of hydrogenic ions

The measurement of the gj factor of the bound electron is a sensitive test of bound state QED. The theoretical relevance and some experimental aspects of the measurement of the gj factor of hydrogenic ions are discussed.