Muonic Hydrogen and the Proton Radius Puzzle Pohl, Randolf; Gilman, Ronald; Miller, Gerald A. ...
Annual review of nuclear and particle science,
10/2013, Letnik:
63, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The extremely precise extraction of the proton radius obtained by Pohl et al. from the measured energy difference between the 2P and 2S states of muonic hydrogen disagrees significantly with that ...extracted from electronic hydrogen or elastic electron–proton scattering. This discrepancy is the proton radius puzzle. In this review, we explain the origins of the puzzle and the reasons for believing it to be very significant. We identify various possible solutions of the puzzle and discuss future research needed to resolve the puzzle.
The Rydberg constant and proton size from atomic hydrogen Beyer, Axel; Maisenbacher, Lothar; Matveev, Arthur ...
Science (American Association for the Advancement of Science),
10/2017, Letnik:
358, Številka:
6359
Journal Article
Recenzirano
Odprti dostop
At the core of the “proton radius puzzle” is a four–standard deviation discrepancy between the proton root-mean-square charge radii (r
p) determined from the regular hydrogen (H) and the muonic ...hydrogen (μp) atoms. Using a cryogenic beam of H atoms, we measured the 2S-4P transition frequency in H, yielding the values of the Rydberg constant R
∞ = 10973731.568076(96) per meter and r
p = 0.8335(95) femtometer. Our r
p value is 3.3 combined standard deviations smaller than the previous H world data, but in good agreement with the μp value. We motivate an asymmetric fit function, which eliminates line shifts from quantum interference of neighboring atomic resonances.
We have performed two-photon ultraviolet direct frequency comb spectroscopy on the 1S-3S transition in atomic hydrogen to illuminate the so-called proton radius puzzle and to demonstrate the ...potential of this method. The proton radius puzzle is a significant discrepancy between data obtained with muonic hydrogen and regular atomic hydrogen that could not be explained within the framework of quantum electrodynamics. By combining our result
= 2,922,743,278,665.79(72) kilohertz with a previous measurement of the 1S-2S transition frequency, we obtained new values for the Rydberg constant
= 10,973,731.568226(38) per meter and the proton charge radius
= 0.8482(38) femtometers. This result favors the muonic value over the world-average data as presented by the most recent published CODATA 2014 adjustment.
The 7σ discrepancy between the proton rms charge radius from muonic hydrogen and the CODATA-2010 value from hydrogen spectroscopy and electron-scattering has caused considerable discussions. Here, we ...review the theory of the 2S–2P Lamb shift and 2S hyperfine splitting in muonic hydrogen combining the published contributions and theoretical approaches. The prediction of these quantities is necessary for the determination of both proton charge and Zemach radii from the two 2S–2P transition frequencies measured in muonic hydrogen; see Pohl et al. (2010) 9 and Antognini et al. (2013) 71.
► We update the theory of Lamb shift and hyperfine splitting in muonic hydrogen. ► We found no large error or missing contribution larger than 0.001 meV. ► We critically discuss the proton-structure-dependent contributions. ► The proton radius puzzle still remains.
The breaking of a property of nature called charge-parity-time symmetry might explain the observed lack of antimatter in the Universe. Scientists have now hunted for such symmetry breaking using the ...antimatter atom antihydrogen.
The toolbox for material characterization has never been richer than today. Great progress with all kinds of particles and interaction methods provide access to nearly all properties of an object ...under study. However, a tomographic analysis of the subsurface region remains still a challenge today. In this regard, the Muon Induced X-ray Emission (MIXE) technique has seen rebirth fueled by the availability of high intensity muon beams. We report here a study conducted at the Paul Scherrer Institute (PSI). It demonstrates that the absence of any beam time-structure leads to low pile-up events and a high signal-to-noise ratio (SNR) with less than one hour acquisition time per sample or data point. This performance creates the perspective to open this technique to a wider audience for the routine investigation of non-destructive and depth-sensitive elemental compositions, for example in rare and precious samples. Using a hetero-structured sample of known elements and thicknesses, we successfully detected the characteristic muonic X-rays, emitted during the capture of a negative muon by an atom, and the gamma-rays resulting from the nuclear capture of the muon, characterizing the capabilities of MIXE at PSI. This sample emphasizes the quality of a continuous beam, and the exceptional SNR at high rates. Such sensitivity will enable totally new statistically intense aspects in the field of MIXE, e.g., elemental 3D-tomography and chemical analysis. Therefore, we are currently advancing our proof-of-concept experiments with the goal of creating a full fledged permanently operated user station to make MIXE available to the wider scientific community as well as industry.
We, the QUARTET Collaboration, propose an experiment to measure the nuclear charge radii of light elements with up to 20 times higher accuracy. These are essential both for understanding nuclear ...physics at low energies, and for experimental and theoretical applications in simple atomic systems. Such comparisons advance the understanding of bound-state quantum electrodynamics and are useful for searching for new physics beyond the Standard Model. The energy levels of muonic atoms are highly susceptible to nuclear structure, especially to the mean square charge radius. The radii of the lightest nuclei (with the atomic number, Z=1,2) have been determined with high accuracy using laser spectroscopy in muonic atoms, while those of medium mass and above were determined using X-ray spectroscopy with semiconductor detectors. In this communication, we present a new experiment, aiming to obtain precision measurements of the radii of light nuclei 3≤Z≤10 using single-photon energy measurements with cryogenic microcalorimeters; a quantum-sensing technology capable of high efficiency with outstanding resolution for low-energy X-rays.
Precision spectroscopy of the 2S − 4P1/2 and 2S − 4P3/2 transitions in atomic hydrogen is performed with a reproducibility of a few parts in 1012. A cryogenic beam of metastable 2S atoms is obtained ...by optical excitation, avoiding excessive heating of electron impact excitation used in all previous experiments of this kind. Despite the low temperature of 5.8 K, the first‐order Doppler effect is the dominating systematic shift, which is suppressed to a very high degree. The effectiveness of this suppression is verified by employing a time‐resolved detection scheme. This experiment should contribute to an improved determination of the Rydberg constant and the proton r.m.s. charge radius.
Precision spectroscopy of the 2S − 4P1/2 and 2S − 4P3/2 transitions in atomic hydrogen is performed with a reproducibility of a few parts in 1012. A cryogenic beam of metastable 2S atoms is obtained by optical excitation, avoiding excessive heating of electron impact excitation used in all previous experiments of this kind. Despite the low temperature of 5.8 K, the first‐order Doppler effect is the dominating systematic shift, which is suppressed to a very high degree. The effectiveness of this suppression is verified by employing a time‐resolved detection scheme. This experiment should contribute to an improved determination of the Rydberg constant and the proton r.m.s. charge radius.
A multipass laser cavity is presented which can be used to illuminate an elongated volume from a transverse direction. The illuminated volume can also have a very large transverse cross section. ...Convenient access to the illuminated volume is granted. The multipass cavity is very robust against misalignment, and no active stabilization is needed. The scheme is suitable for example in beam experiments, where the beam path must not be blocked by a laser mirror, or if the illuminated volume must be very large. This cavity was used for the muonic-hydrogen experiment in which 6 μm laser light illuminated a volume of 7 × 25 × 176 mm3, using mirrors that are only 12 mm in height. We present our measurement of the intensity distribution inside the multipass cavity and show that this is in good agreement with our simulation.
PDF
