https://doi.org/10.1140/epjd/s10053-023-00605-9
Regular Article – Atomic Physics
1S–3S cw spectroscopy of hydrogen/deuterium atom
1
Laboratoire Kastler Brossel, Sorbonne Université, CNRS, ENS-PSL Research University, Collège de France, 4 Place Jussieu, Case 74, 75252, Paris Cedex 05, France
2
Laboratoire de Physique des Lasers, Université Sorbonne Paris Nord (USPN), Institut Galilée, 99, Av. J.B. Clément, 93430, Villetaneuse, France
a
pauline.yzombard@lkb.upmc.fr
Received:
22
December
2022
Accepted:
24
January
2023
Published online:
8
February
2023
We study the 1S–3S two-photon transition of hydrogen in a thermal atomic beam, using a home-made cw laser source at 205 nm. The experimental method is described, leading in 2017 to the measurement of the 1S–3S transition frequency in hydrogen atom with a relative uncertainty of 
. This result contributes to the “proton puzzle” resolution but is in disagreement with the ones of some others experiments. We have recently improved our set-up with the aim of carrying out the same measurement in deuterium. With the improved detection system, we have observed a broadened fluorescence signal, superimposed on the narrow signal studied so far, and due to the stray accumulation of atoms in the vacuum chamber. The possible resulting systematic effect is discussed.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2023. Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
