MEASUREMENT OF THE GROUND-STATE LAMBSHIFT OF HYDROGENLIKE URANIUM AT THE ELECTRON COOLER OF THE ESR

X-rays are emitted with the radiative recombination of free electrons in an electron cooler of a heavy-ion storage ring. Due to a small width of the X-ray lines, an observation angle close to 0 degrees and an accurate determination of the ion velocity, the ground-state Lambshift of hydrogenlike uranium (470 +/- 16) eV could be measured to an accuracy of 3.4%. A re-evaluation of a measurement of the 1s(1/2) Lambshift in hydrogenlike gold gave a new value of (202.3 +/- 7.9) eV as compared to the former value of(212 +/- 15) eV. The results are in excellent agreement with QED calculations and are more precise than any other measurements previously reported for a high-Z, hydrogenlike ion.