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A: Fachverband Atomphysik

A 15: Precision spectroscopy of atoms and ions / Highly charge ions (joint session A/Q)

A 15.2: Hauptvortrag

Mittwoch, 22. September 2021, 14:30–15:00, H1

Status update of the muonic hydrogen ground-state hyperfine splitting experiment — •A. Ouf and R. Pohl on behalf of the CREMA collaboration — Johannes Gutenberg-Universität Mainz, Institut für Physik, QUANTUM & Exzellenzcluster PRISMA +, Mainz, Germany

The ground state hyperfine splitting (1S-HFS) in ordinary hydrogen (the famous 21 cm line) has been measured with 12 digits accuracy almost 50 years ago [1], but its comparison with QED calculations is limited to 6 digits by the uncertainty of the Zemach radius determined from elastic electron-proton scattering. The Zemach radius encodes the magnetic properties of the proton and it is the main nuclear structure contribution to the hyperfine splitting (HFS) in hydrogen. The ongoing experiment of the CREMA Collaboration at PSI aims at the first measurement of the 1S-HFS in muonic hydrogen (µp) with the potential for a hundredfold improved determination of the proton structure effects (Zemach radius and polarizability), which will eventually improve the QED test using the 21 cm line by a factor of 100. The experiment introduces several novel developments toward the (µp) 1s-HFS spectroscopy. We will present the current efforts of the various developments from the pulsed 6.8   µ m laser, to the novel multi pass cavity, and the scintillator detection system.

[1] L. Essen et al, Nature 229, 110 (1971)
[2] R. Pohl et al., Nature 466, 213 (2010)
[3] A. Antognini et al., Science 339, 417 (2013)