a Differential Measurement of the Ground State Lamb Shift in Hydrogenic Germanium, GERMANIUM(31+)
Abstract
Available from UMI in association with The British Library. Requires signed TDF. The 1s-2p Lyman alpha transitions in hydrogenic Germanium, Ge^{31+} , have been observed in fourth order of diffraction by Si 111 crystals from a beam-foil light source, simultaneously with the n = 2 to n = 4 Balmer beta transitions in first order of diffraction. This enables a measurement of the Lyman alpha wavelengths using the Balmer beta transitions as calibrations. This is possible because of the near 4:1 ratio in wavelengths between the Balmer beta and Lyman alpha lines. The ground state Lamb shift is deduced from the Lyman alpha wavelengths, after subtracting the Dirac energy and other smaller contributions. The results for the Lyman alpha _{1,2} wavelengths are 1.166861 (46) A and 1.172302 (41) A respectively, in rather poor agreement with theory. Any suspicion of the theoretical calculations is ruled out by a similar analysis of the Lyman beta doublet with respect to the Balmer delta fine structure, which shows a discrepancy in ppm approximately twice as large. The possible systematic effects which might give rise to such a shift are investigated. Details of the electron capture process, by which the hydrogenic ions are excited from a bare nucleus, can lead to uncertainties in the intensities of the Balmer beta fine structure components. Since the fine structure is not completely resolved, difficulties exist in fitting the blended lines, which could readily account for the discrepancies. With a view to improving the resolution of x-ray spectroscopy of highly stripped ions, experiments in which beam-foil and beam-gas sources are observed from a position on the beam axis are described, together with some data including possibly the best resolved beam-foil spectrum yet obtained, that of Lyman alpha in Ne^{9+}.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1988
- Bibcode:
- 1988PhDT.......166L
- Keywords:
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- GERMANIUM;
- Physics: Elementary Particles and High Energy