Progress in Spectroscopy of the 1S–3S Transition in Hydrogen

Galtier, Sandrine; Fleurbaey, Hélène; Thomas, Simon; Julién, L.; Biraben, F.; Nez, F.

doi:10.1063/1.4922255

Cited by 25 publications

(20 citation statements)

References 22 publications

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“…New scattering experiments are in preparation or underway, including electron-proton [10], electron-deuteron [11] and muon-proton scattering [12]. In atomic hydrogen, the 1S-3S(D) [13,14], 2S-2P [15], and 2S-4P [16] transitions are under study in order to cross-check and improve previous results. An independent determination of R ∞ , which is strongly correlated to r p and r d , is another way to shed new light on this problem.…”

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confidence: 99%

Hydrogen molecular ions for improved determination of fundamental constants

et al. 2016

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The possible use of high-resolution rovibrational spectroscopy of the hydrogen molecular ions H + 2 and HD+ for an independent determination of several fundamental constants is analyzed. While these molecules had been proposed for metrology of nuclear-to-electron mass ratios, we show that they are also sensitive to the radii of the proton and deuteron and to the Rydberg constant at the level of the current discrepancies colloquially known as the proton size puzzle. The required level of accuracy, in the 10 −12 range, can be reached both by experiments, using Doppler-free two-photon spectroscopy schemes, and by theoretical predictions. It is shown how the measurement of several well-chosen rovibrational transitions may shed new light on the proton-radius puzzle, provide an alternative accurate determination of the Rydberg constant, and yield new values of the proton-toelectron and deuteron-to-proton mass ratios with one order of magnitude higher precision. From Bohr's model of the atom to the advent of quantum electrodynamics (QED), precision spectroscopy of atomic hydrogen has played a key role in our understanding of matter and its interaction with light. Since the first measurement of the Lamb shift in 1947 [1, 2], the predictions of QED have been verified with an increasing level of accuracy which, together with stringent tests in other areas of physics, led to assume the validity of this theory and use it to extract the values of fundamental physical constants from experimental data [3]. Specifically, available data on the hydrogen (H) and deuterium (D) atoms are used to extract the Rydberg constant R ∞ and the charge radii of the proton (r p ) and deuteron (r d ). Data from electron-proton and electron-deuteron scattering experiments also contribute in this determination.Recently, the undisputed status of these results has been challenged by the measurement of the Lamb shift in muonic hydrogen [4,5]. The very precise value of r p deduced from this experiment is in strong disagreement with previous determinations. The discrepancy with the CODATA adjustment [6] amounts to 5.6σ, or to 4.5σ if only the H and D data are taken into account [3]. Similar discrepancies on the deuteron radius can be inferred through the very precise determination of r 2 d − r 2 p from the 1S-2S H/D isotopic shift [7]. Although many efforts have been undertaken in the last few years, no convincing solution of the "proton size puzzle" has been found so far (see [8] for a review). One of the possible explanations is that the error bars, both of hydrogen spectroscopy and scattering experiments [9] were underestimated. New scattering experiments are in preparation or underway, including electron-proton [10], electron-deuteron [11] and muon-proton scattering [12]. In atomic hydrogen, the 1S-3S(D) [13,14], 2S-2P [15], and 2S-4P [16] transitions are under study in order to cross-check and improve previous results. An independent determination of R ∞ , which is strongly correlated to r p and r d , is another way to shed new light on this prob...

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Hydrogen molecular ions for improved determination of fundamental constants

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“…A large activity both, theoretical and experimental, have been triggered by the observed discrepancy, which remains still unsolved. Many new activities are underway, such as spectroscopy in (regular) atomic hydrogen [106][107][108][109][110], molecular hydrogen (and its isotopes) [111][112][113][114], and He + ions [77][78][79][80][81][82][83], new elastic electron scattering experiments [115][116][117][118], and muon scattering on the proton [119].…”

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Laser Spectroscopy of Muonic Atoms and Ions

Pohl

Nez

Fernandes

et al. 2017

Proceedings of the 12th International Conference on Low Energy Antiproton Physics (LEAP2016)

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Laser spectroscopy of the Lamb shift (2S-2P energy difference) in light muonic atoms or ions, in which one negative muon µ − is bound to a nucleus, has been performed. The measurements yield significantly improved values of the root-mean-square charge radii of the nuclei, owing to the large muon mass, which results in a vastly increased muon wave function overlap with the nucleus. The values of the proton and deuteron radii are 10 and 3 times more accurate than the respective CODATA values, but 7 standard deviations smaller. Data on muonic helium-3 and -4 ions is being analyzed and will give new insights. In future, the (magnetic) Zemach radii of the proton and the helium-3 nuclei will be determined from laser spectroscopy of the 1S hyperfine splittings, and the Lamb shifts of muonic Li, Be and B can be used to improve the respective charge radii.

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“…The absolute frequencies of the two radiations at 532 nm and 894 nm were measured with an optical frequency comb referenced to the Cs clock of the LNE-SYRTE laboratory. The statistical uncertainty on the deduced transition frequency has been significantly improved to reach a value of 2.2 kHz [53]. However, a complete analysis of systematic shifts of the line, in particular collisional shifts, was still needed to determine the 1S-3S transition frequency.…”

Section: From 2s-ns/nd To 1s-3s Spectroscopymentioning

confidence: 99%

“…On the side of experiments in hydrogen atom, a new RF measurement of the 2S-2P hydrogen interval is currently in progress in the group of Hessels [61] while the Paris and Garching groups pursue their efforts to improve their optical measurements: in the one-photon 2S-4P transition [62] (cw laser in Garching) and in the two-photon 1S-3S transition [53,63] (pulsed laser in Garching and cw laser in Paris). At the level of precision needed to clarify the proton puzzle, all stray shifting effects have to be carefully studied, including quantum cross-damping interference effects [64][65][66].…”

Section: The Hydrogen Atom a Still Hot Topicmentioning

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Thirty Years of Hydrogen Spectroscopy in Paris

Biraben

Julién

Nez

2018

Exploring the World With the Laser

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several years, we also moved to the 1S-3S transition, a transition from the ground state, which is nowadays still under study in our group.We show in this paper how Paris works in atomic hydrogen have been stimulated by the ones of Ted Hänsch's groups, first in Stanford and then in Garching, and how they developed in a context where an healthy competition turned often into collaboration and joint efforts for a common goal. The beginning of the Paris storyAt the beginning, we (FB and LJ) were then only two people on the hydrogen project in Paris, with the scientific support of Bernard Cagnac who founded a few years before in our laboratory a group devoted to Doppler-free two-photon spectroscopy. He himself had pointed out for the first time the advantage of this spectroscopy for the study of the 1S-2S transition in hydrogen [4] but without undertaking such an experiment since Ted Hänsch seized this subject very quickly. It is why we decided to study other hydrogen lines.One of us (F.B.) had already a very good expertise in high-resolution spectroscopy, having studied two-photon transitions in sodium [5] and rare gas atoms [6,7]. The other one (L.J.) had previously measured atomic structures and Lamb shifts in excited hydrogen states by an anticrossing method [8].Our target was to excite the n ≥ 8 states because the wavelength range needed 730-778 nm was easily obtained with our homemade dye laser.In a first step, we had to build a 2S metastable atomic beam, which was obtained by the following method: molecular hydrogen is dissociated by a RF discharge in a Abstract This paper gives a review of the experiments performed since the 1980s at the Laboratoire Kastler Brossel in Paris on two-photon spectroscopy of atomic hydrogen. Firstly devoted to the 2S-nS and 2S-nD transitions, they are currently running on the 1S-3S transition at 205 nm. During all that time, they were inspired by the plentiful ideas proposed by Ted Hänsch and were complementary with the measurements developed in parallel in his groups.

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Progress in Spectroscopy of the 1S–3S Transition in Hydrogen

Cited by 25 publications

References 22 publications

Hydrogen molecular ions for improved determination of fundamental constants

Hydrogen molecular ions for improved determination of fundamental constants

Laser Spectroscopy of Muonic Atoms and Ions

Thirty Years of Hydrogen Spectroscopy in Paris

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