ISOLDE Seminar

Proton/Antiproton Magnetic Moments and the Hyperfine Structure of Antihydrogen

by Stefan Ulmer (I)

26-1-022 (CERN)



The precision spectroscopy of simple antimatter systems and the comparison to their matter counterparts contributes to our understanding of the matter/antimatter asymmetry which is observed on cosmological scales. Specifically interesting are experimental studies of systems at an ultra-low absolute energy scale, as the comparison of the magnetic moment of the proton and the antiproton, or the hyperfine structure of hydrogen and antihydrogen. In 2011 we observed for the first time spin flips with a single trapped proton, which is a major step towards a high precision measurement of the particle’s magnetic moment. Based on these results measurements at a precision close to the ppm-level were performed in a Penning trap with a superimposed inhomogeneous magnetic field. Applying the method to a single antiproton, the particle’s magnetic moment can be improved now by three orders of magnitude. Recently the ATRAP collaboration reported on a first determination of the magnetic moment of the antiproton at a level of 4.4ppm. Using a double-Penning trap scheme the ATRAP collaboration as well as the BASE collaboration intend to improve this precision down to the ppb-level, at least. Another experiment which investigates the properties of antimatter at a comparable energy scale as the one described above is the precision comparison of the hyperfine structure of hydrogen and antihydrogen. Antihydrogen was recently produced in a so-called CUSP, which is utilized to produce a polarized anti-atomic beam. This can be used to perform precision hyperfine-spectroscopy by application of a Rabi-like beam-spectroscopy scheme. In my talk I will report on recent progress of both efforts.
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