Precise determination of the 1s Lamb shift in hydrogen-like lead and gold using microcalorimeters

Abstract

Quantum electrodynamics in very strong Coulomb fields is one scope which has not yet been tested experimentally with sufficient accuracy to really determine whether the perturbative approach is valid. One sensitive test is the determination of the 1s Lamb shift in highly-charged very heavy ions. The 1s Lamb shift of hydrogen-like lead (Pb 81+ ) and gold (Au 78+ ) has been determined using the novel detector concept of silicon microcalorimeters for the detection of hard x-rays. The results of  260 53 ( ) eV for lead and  211 42 () eV for gold are within the error bars in good agreement with theoretical predictions. To our knowledge, for hydrogen-like lead, this represents the most accurate determination of the 1s Lamb shift.

Wavelength-dispersive spectroscopy in the hard x-ray regime of a heavy highly-charged ion: the 1s Lamb shift in hydrogen-like gold

“…= ( ) eV. In table 3 our result is compared to the experimental value obtained with a Ge(i) detector in an early experiment at the ESR electron cooler [44] and to the experimental result reported for the calorimetric lowtemperature detectors which was obtained in the same beam time [30] as our present experiment. In the last entry of table 3 the theoretical value of Yerokhin and Shabaev [9] is given.…”

“…This is especially interesting in the light of the recent controversy with the comparison between the experimental and theoretical results for helium-like ions [47][48][49][50][51][52][53][54]. Beyer et al 1995 [44] 202.3(7.9) Kraft-Bermuth et al 2016 [30] 211(42) Theory, Yerokhin and Shabaev 2015 [9] 205.2 (2)…”

“…However, in the case of the Lamb shift of the 1s level in high-Z H-like systems, where the strongest Coulomb fields can be obtained, the spectroscopy needed to be conducted with solid state Ge(i) detectors ensuring a high detection efficiency, although they soon faced their limits in spectral resolution. To circumvent the low resolving power of semiconductor detectors, they were replaced by specially adapted crystal spectrometers, as will be reported in this letter, and by calorimetric low-temperature detectors yielding promising results in first storagering experiments [30,31]. In the present experiment a pair of crystal spectrometers was used to measure the 1s Lamb shift of hydrogen-like gold accomplishing for the first time both, high-Z ions and high spectral resolution.…”

“…Without going into details of the other results which would be beyond the scope of this article, it should be stated that these measurements have all been performed with different techniques, i.e. semiconductor detector at the electron cooler [44], microcalorimeter at the gas-jet target [30] and thus are prone to different systematic effects. It is important to emphasize that even though we have performed very thorough and extensive studies of the various possible systematic effects, since this is the first measurement of its kind at the storage ring, potentially underestimated or unknown systematic effects cannot be fully excluded.…”

Lamb Shift Approximation for Elements up to 80 in a Very Simple Way

“…In addition, students with just an introductory course in physics and little or no knowledge of quantum electrodynamics can gain some basic intuition about the approximate size of the Lamb shift for a single electron.Our approximation formula also provides good predictions for the higher elements. Recently,[8] measured the Lamb shift for hydrogen-like lead and gold using microcalorimeters. They measured (211 ± 42) eV for hydrogen-like gold and (260 ± 53) eV for hydrogen-like lead.…”