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Hyperfine structure measurements on antihydrogen are a sensitive tool for CPT tests by comparison to hydrogen. Toward this goal the ASACUSA collaboration proposed to perform Rabi-type spectroscopy on a beam of antihydrogen at the antiproton decelerator of CERN. This approach promises high precision and accuracy, as the interaction takes place at a distance from the strong magnetic fields required at the antihydrogen production region. We have benchmarked the spectroscopy methods and equipment in supporting matter experiments. Beyond the relevance for antihydrogen these measurements can put new or improved constraints on specific coefficients of the so-called Standard Model Extension (SME). Thereby, CPT and Lorentz invariance is tested even without comparison to antihydrogen. We have constructed an atomic beam setup for Rabi spectroscopy and performed such measurements on hydrogen at CERN and on deuterium at the Laboratoire Aimé Cotton, Université Paris-Saclay. In the latter, searches for sidereal variations result in new and improved constraints by exploiting an enhanced sensitivity, which originates from the relative proton momentum in the deuteron. In contrast, the hydrogen measurement accessed a set of coefficients, which are insensitive to sidereal variations, by repeated swaps of the experiment's magnetic field. In absence of symmetry violations the data provides for both hydrogen isotopes the most precise values for the zero-field hyperfine splittings obtained from a beam experiment. Finally, the relevance of the hydrogen measurement for antihydrogen hyperfine spectroscopy will be discussed together with a glimpse on the latest antihydrogen beam developments at CERN.
Hybrid access via ZOOM:
https://lmu-munich.zoom.us/j/98457332925?pwd=TWc3V1JkSHpyOTBPQVlMelhuNnZ1dz09
Meeting ID: 984 5733 2925
Passcode: 979953
Peter Thirolf (LMU) / Norbert Kaiser (TUM)