Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 9: Precision spectroscopy of atoms and ions II (with Q)

A 9.2: Talk

Monday, March 17, 2014, 14:15–14:30, BEBEL E42

Progress towards antihydrogen hyperfine spectroscopy in a beam — •Eberhard Widmann — Stefan Meyer Institute for Subatomic Physics, Vienna, Austria, on behalf of the ASACUSA CUSP collaboration

The spectroscopy of antihydrogen promises one of the most precise tests of CPT symmetry. The ASACUSA CUSP collaboration at the Antiproton Decelerator of CERN is preparing an experiment to measure the ground-state hyperfine structure GS-HFS of antihydrogen, since this quantity is one of the most precisely determined transitions in ordinary hydrogen (relative accuracy ∼ 10⁻¹²). The experiment uses a Rabi-type atomic beam apparatus consisting of a source of spin-polarized anthihydrogen (a so-called cusp trap), a microwave cavity to induce a spin flip, a superconducting sextuple magnet for spin analysis, and an antihydrogen detector. In this configuration, a relative accuracy of better than 10⁻⁶ can be obtained. This precision will already allow to be sensitive to finite size effects of the antiproton, provided its magnetic moment will measured to higher precision, which is in progress by two collaborations at the AD.

The recent progress in producing a beam of antihydrogen atoms and in the development of the apparatus as well as ways to further improve the accuracy by using the Ramsey method of separated oscillatory fields will be presented.