scholarly journals Status of the muonic hydrogen Lamb-shift experiment

2007 ◽  
Vol 85 (5) ◽  
pp. 469-478 ◽  
Author(s):  
T Nebel ◽  
F D Amaro ◽  
A Antognini ◽  
F Biraben ◽  
J MR Cardoso ◽  
...  
Keyword(s):  
Charge Radius ◽  
Lamb Shift ◽  
Bound State ◽  
Muonic Hydrogen ◽  
X Ray ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Experimental Apparatus ◽  
Shift Experiment ◽  
Bound State Qed

The Lamb-shift experiment in muonic hydrogen (μ– p) aims to measure the energy difference between the [Formula: see text] atomic levels to a precision of 30 ppm. This would allow the r.m.s. proton charge radius rp to be deduced to a precision of 10–3 and open a way to check bound-state quantum electrodynamics (QED) to a level of 10–7. The poor knowledge of the proton charge radius restricts tests of bound-state QED to the precision level of about 6 × 10–6, although the experimental data themselves (Lamb-shift in hydrogen) have reached a precision of  × 10–6. Values for rp not depending on bound-state QED results from electron scattering experiments have a surprisingly large uncertainty of 2%. In our Lamb-shift experiment, low-energy negative muons are stopped in low-density hydrogen gas, where, following the μ– atomic capture and cascade, 1% of the muonic hydrogen atoms form the metastable 2S state with a lifetime of about 1 μs. A laser pulse at λ ≈ 6 μm is used to drive the 2S → 2P transition. Following the laser excitation, we observe the 1.9 keV X-ray being emitted during the subsequent de-excitation to the 1S state using large-area avalanche photodiodes. The resonance frequency and, hence, the Lamb shift and the proton charge radius are determined by measuring the intensity of the X-ray fluorescence as a function of the laser wavelength. The results of the run in December 2003 were negative but, nevertheless, promising. One by-product of the 2003 run was the first observation of the short-lived 2S component in muonic hydrogen. Currently, improvements in the laser-system, the experimental apparatus, and the data acquisition are being implemented. PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi

The muonic hydrogen Lamb-shift experiment

2005 ◽  
Vol 83 (4) ◽  
pp. 339-349 ◽  
Author(s):  
R Pohl ◽  
A Antognini ◽  
F D Amaro ◽  
F Biraben ◽  
J MR Cardoso ◽  
...  
Keyword(s):  
Charge Radius ◽  
Quantum Electrodynamics ◽  
Lamb Shift ◽  
Laser System ◽  
Bound State ◽  
Muonic Hydrogen ◽  
X Rays ◽  
Large Area ◽  
Proton Charge ◽  
Proton Charge Radius

The charge radius of the proton, the simplest nucleus, is known from electron-scattering experiments only with a surprisingly low precision of about 2%. The poor knowledge of the proton charge radius restricts tests of bound-state quantum electrodynamics (QED) to the precision level of about 6 × 10–6, although the experimental data themselves (1S Lamb shift in hydrogen) have reached a precision of 2 × 10–6. The determination of the proton charge radius with an accuracy of 10–3 is the main goal of our experiment, opening a way to check bound-state QED predictions to a level of 10–7. The principle is to measure the 2S–2P energy difference in muonic hydrogen (µ–p) by infrared laser spectroscopy. The first data were taken in the second half of 2003. Muons from our unique very-low-energy muon beam are stopped at a rate of ~100 s–1 in 0.6 mbar H2 gas where the lifetime of the formed µp(2S) atoms is about 1.3 µs. An incoming muon triggers a pulsed multistage laser system that delivers ~0.2 mJ at λ ≈ 6 µm. Following the laser excitation µp(2S) → µp(2P) we observe the 1.9 keV X-rays from 2P–1S transitions using large area avalanche photodiodes. The resonance frequency, and, hence, the Lamb shift and the proton radius, is determined by measuring the intensity of these X-rays as a function of the laser wavelength. A broad range of laser frequencies was scanned in 2003 and the analysis is currently under way. PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi

The Lamb shift in muonic hydrogenThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

2011 ◽  
Vol 89 (1) ◽  
pp. 37-45 ◽  
Author(s):  
Randolf Pohl ◽  
Aldo Antognini ◽  
François Nez ◽  
Fernando D. Amaro ◽  
François Biraben ◽  
...  
Keyword(s):  
Charge Radius ◽  
Lamb Shift ◽  
Finite Size ◽  
Muonic Hydrogen ◽  
Energy Splitting ◽  
Atomic Systems ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Rydberg Constant ◽  
Better Than

The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measured the 2S 1/2F=1 –2P 3/2F=2 energy splitting (Pohl et al., Nature, 466, 213 (2010)) in μp with an experimental accuracy of 15 ppm, twice better than our proposed goal. Using current QED calculations of the fine, hyperfine, QED, and finite size contributions, we obtain a root-mean-square proton charge radius of rp = 0.841 84 (67) fm. This value is 10 times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp. The origin of this discrepancy is not known. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, gives improved values of the Rydberg constant, R∞ = 10 973 731.568 160 (16) m–1 and the rms charge radius of the deuteron rd = 2.128 09 (31) fm.

scholarly journals Addendum to "Quantum Gravity and the Holographic Mass" in view of the 2013 Muonic Proton Charge Radius Measurement

2019 ◽  
Author(s):  
Nassim Haramein
Keyword(s):  
Standard Deviation ◽  
Charge Radius ◽  
Rest Mass ◽  
Muonic Hydrogen ◽  
Proton Accelerator ◽  
Proton Charge ◽  
Proton Mass ◽  
Proton Charge Radius ◽  
Holographic Approach ◽  
Paul Scherrer

We consider the latest results of the measurement of the charge radius of the proton utilizing laser spectroscopy of muonic hydrogen published in Science on January 25, 2013 by an international team lead by Aldo Antognini and carried out at the Paul Scherrer Institute Proton Accelerator. Given the new charge radius measurement, we compute the proton mass utilizing our generalized holographic approach and find that our result is now within 0.00072x10e-24 g of the 2010-CODATA value of the proton rest mass. Our predicted charge radius is now within 0.00036x10e-13 cm and remains within one standard deviation of the new measurement.

A measurement of the atomic hydrogen Lamb shift and the proton charge radius

Science ◽  
2019 ◽  
Vol 365 (6457) ◽  
pp. 1007-1012 ◽  
Author(s):  
N. Bezginov ◽  
T. Valdez ◽  
M. Horbatsch ◽  
A. Marsman ◽  
A. C. Vutha ◽  
...  
Keyword(s):  
Direct Measurement ◽  
Charge Radius ◽  
Atomic Hydrogen ◽  
Lamb Shift ◽  
Shift Measurement ◽  
Proton Radius ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Proton Radius Puzzle

The surprising discrepancy between results from different methods for measuring the proton charge radius is referred to as the proton radius puzzle. In particular, measurements using electrons seem to lead to a different radius compared with those using muons. Here, a direct measurement of the n = 2 Lamb shift of atomic hydrogen is presented. Our measurement determines the proton radius to be rp = 0.833 femtometers, with an uncertainty of ±0.010 femtometers. This electron-based measurement of rp agrees with that obtained from the analogous muon-based Lamb shift measurement but is not consistent with the larger radius that was obtained from the averaging of previous electron-based measurements.

scholarly journals Pure bound field corrections to the atomic energy levels and the proton size puzzle

2014 ◽  
Vol 92 (4) ◽  
pp. 321-327 ◽  
Author(s):  
Alexander L. Kholmetskii ◽  
Oleg V. Missevitch ◽  
Tolga Yarman
Keyword(s):  
Lamb Shift ◽  
Energy Levels ◽  
Muonic Hydrogen ◽  
Momentum Conservation ◽  
Mean Value ◽  
Crucial Experiment ◽  
Present Contribution ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
The Difference

Reinforcement of the puzzle about the proton charge radius, rE, stimulated by the recent experiment with muonic hydrogen (Antognini et al. Science, 339, 417 (2013)) induced new discussions on the subject, and now some physicists are ready to adopt the exotic properties of the muon, lying beyond the Standard Model, to explain the difference between the results of muonic hydrogen experiments (rE = 0.840 87(39) fm) and the CODATA-2010 value rE = 0.8775(51) fm based on electron–proton scattering and hydrogen spectroscopy. In the present contribution we suggest a way to achieve progress in the entire problem via paying attention on some logical inconsistency of fundamental equations of atomic physics, constructed by analogy with corresponding classical equations without, however, taking into account the purely bound nature of electromagnetic fields generated by the electrically bound particles in stationary energy states. We suggest eliminating this inconsistency via introducing some appropriate correcting factors into these equations, which explicitly involve the requirement of total momentum conservation in the system “bound particles and their fields” in the absence of electromagnetic radiation. We further show that this approach allows us not only to eliminate long-standing discrepancies between theory and experiment in the precise physics of simple atoms, but also yields the same estimation (though with different uncertainties) for the proton size in the classic 2S–2P Lamb shift in hydrogen, 1S Lamb shift in hydrogen, and 2S–2P Lamb shift in muonic hydrogen, with the mean value rE = 0.841 fm. Finally, we suggest the crucial experiment for verification of the validity of pure bound field corrections: the measurement of decay rate of bound moun in various meso-atoms, especially at large Z, where the standard calculations and our predictions essentially deviate from each other, and some of the available experimental results (Yovanovitch. Phys. Rev. 117, 1580 (1960)) strongly support our approach.

scholarly journals ISR Experiment at A1-Collaboration

2019 ◽  
Vol 218 ◽  
pp. 04001 ◽  
Author(s):  
Miha Mihovilovič ◽  
Harald Merkel
Keyword(s):  
Nuclear Physics ◽  
Lamb Shift ◽  
Muonic Hydrogen ◽  
Present Value ◽  
Elastic Peak ◽  
Shift Measurement ◽  
Elastic Line ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Electromagnetic Processes

The discrepancy between the proton charge radius extracted from the muonic hydrogen Lamb shift measurement and the best present value obtained from the elastic scattering experiments, remains unexplained and represents a burning problem of today’s nuclear physics. In a pursuit of reconciling the puzzle an experiment is underway at MAMI, which exploits the radiative tail of the elastic peak to study the properties of electromagnetic processes and to extract the proton charge form factor $ \left( {\mathop G\nolimits_E^p } \right) $ at extremely small Q2. This paper reports on the latest results of the first such measurement performed at the three-spectrometer facility of the A1-Collaboration, which led to a precise validation of radiative corrections far away from elastic line and provided measurements of $ \mathop G\nolimits_E^p $ for 0.001 ≤ Q2 ≤ 0.017 (GeV/c)2.

scholarly journals The proton size puzzle: experiment vs theory.

2018 ◽  
Vol 191 ◽  
pp. 04001 ◽  
Author(s):  
A. E. Dorokhov ◽  
A. P. Martynenko ◽  
F. A. Martynenko ◽  
A. E. Radzhabov
Keyword(s):  
Charge Radius ◽  
Axial Vector ◽  
Muonic Hydrogen ◽  
Current Status ◽  
Interaction Operator ◽  
Two Photon ◽  
Proton Charge ◽  
Proton Charge Radius ◽  
Points Of View ◽  
Precise Experimental Data

Current status of the proton size puzzle from experimental and theoretical points of view is briefly discussed. The interest to these studies is primarily related to experiments conducted by the CREMA collaboration (Charge Radius Experi- ments with Muonic Atoms) with muonic hydrogen and deuterium by methods of laser spectroscopy. As a result a more accurate value of the proton charge radius was found to be rp = 0:84184(67) fm, which is different from the value recommended by CODATA for 7σ. In the second part we discuss recent calculations of the contribution of light pseudoscalar (PS) and axial-vector (AV) mesons to the interaction operator of a muon and a proton in muonic hydrogen atom, with the coupling of mesons to the muon being via two-photon intermediate state. Numerical estimates of the contributions to the hyperfine structure of the spectrum of the S and P levels are presented. It is shown that such contribution to the hyperfine splitting in muonic hydrogen is rather important for a comparison with precise experimental data.

What do we actually know about the proton radius?

1999 ◽  
Vol 77 (4) ◽  
pp. 241-266 ◽  
Author(s):  
S G Karshenboim
Keyword(s):  
Charge Radius ◽  
Lamb Shift ◽  
Elastic Electron ◽  
Proton Scattering ◽  
Proton Radius ◽  
Proton Charge ◽  
Proton Charge Radius

This paper considers the different determinations of the proton charge radius. It demonstrates that the results from the elastic electron-proton scattering have to be assigned a higher uncertainty. A review of the hydrogen Lamb-shift measurements and the radius determination from them is also presented.PACS No.: 27.10 and 35.10B

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