Lamb Shift of Exotic Atoms: Precision Measurement in Muonium and Progress Towards the First Direct Determination in Antihydrogen
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Author
Date
2022Type
- Doctoral Thesis
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Abstract
Due to its lack of internal structure, muonium is an excellent candidate to provide stringent tests for bound state QED. This work presents the design and the measurement of the muonium Lamb shift performed at the PSI low energy muon (LEM) beamline in the Mu-MASS (MUoniuM lASer Spectroscopy) experiment. The analysis of the data showed the $n=2$ muonium Lamb shift to be 1047.2(25) MHz, which agrees well with theory and is an improvement of an order of magnitude upon the last measurements.
Additionally, the $2S_{1/2,F=0}\rightarrow2P_{1/2,F=1}$ transition was measured for the first time in muonium at 580.6(6.8) MHz. From the two measurements, the $2S$ hyperfine splitting was extracted to be 559.6(7.2) MHz.
Furthermore, muonium in the excited $n=3$ state was detected for the first time.
In preparation of these measurements, this thesis includes as well the characterization of the intensity of the metastable flux of muonium at LEM by commissioning the antihydrogen Lamb shift setup designed for GBAR.
Physics with antihydrogen is a blossoming field of research which studies aim to shed light on the observed matter-antimatter asymmetry in the Universe. The GBAR project at CERN primarily aims to measure the free fall acceleration of ultracold neutral antihydrogen atoms in the terrestrial gravitational field. The work performed within this dissertation on the Micromegas GBAR tracker is required for the efficient reconstruction of the antihydrogen annihilation vertex and thus essential for the measurement of its free fall. As a parasitic measurement, the Lamb shift of antihydrogen will be measured with the setup presented in this work with a targeted precision of 100 ppm, which would lead to its first direct determination and allow the extraction of the antiproton charge radius to a level of 10%. Show more
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https://doi.org/10.3929/ethz-b-000536696Publication status
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ETH ZurichOrganisational unit
08718 - Crivelli, Paolo (Tit.-Prof.)
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