Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 2: Precision spectroscopy of atoms and ions I (with Q)

A 2.5: Vortrag

Montag, 18. März 2013, 12:00–12:15, B 302

Precision spectroscopy of the 2S−4P_1/2 transition in atomic hydrogen on a cold thermal beam of optically excited 2S atoms — •Axel Beyer¹, Nikolai Kolachevsky¹, Janis Alnis¹, Dylan C. Yost¹, Ksenia Khabarova², Arthur Matveev¹, Christian G. Parthey¹, Randolf Pohl¹, Thomas Udem¹, and Theodor W. Hänsch^1,3 — ¹Max-Planck-Institut für Quantenoptik, 85748 Garching — ²FSUE ’VNIIFTRI’, 141570 Moscow — ³Ludwig-Maximilians-Universität, 80799 München

The ’proton size puzzle’, i.e. the discrepancy between the values for the proton r.m.s. charge radius deduced from precision spectroscopy of atomic hydrogen and electron-proton-scattering on one side and the value deduced from muonic hydrogen spectroscopy on the other side, has been persisting for more than two years now. Although huge efforts have been put into trying to resolve this discrepancy from experimental and theoretical side, no convincing argument could be found so far. In this talk, we report on a unique precision spectroscopy experiment on atomic hydrogen, which is aiming to bring some light to the hydrogen part of the puzzle: In contrast to any previous high resolution experiment probing a transition frequency between the meta-stable 2S state and a higher lying nL state (n=3,4,6,8,12, L=S,P,D), our measurement of the 2S−4P_1/2 transition frequency is the first experiment being performed on a cold thermal beam of hydrogen atoms optically excited to the 2S state. We will discuss how this helps to efficiently suppresses leading systematic effects of previous measurements and present the preliminary results we obtained so far.