Illuminating the proton radius conundrum: the μHe<sup>+</sup> Lamb shiftThis 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.

Antognini, Aldo; Biraben, F.; Cardoso, J. M. R.; Covita, D. S.; Dax, A.; Fernandes, L. M. P.; Gouvea, Andrea L.; Graf, Thomas; Hänsch, T. W.; Hildebrandt, M.; Indelicato, P.; Julién, L.; Kirch, K.; Kottmann, F.; Liu, Yi-Wei; Monteiro, C. M. B.; Mulhauser, F.; Nebel, Tobias; Nez, F.; Santos, J.M.F. dos; Schuhmann, Karsten; Taqqu, D.; Veloso, J.F.C.A.; Voß, Andreas; Pohl, Randolf

doi:10.1139/p10-113

Cited by 72 publications

(42 citation statements)

References 38 publications

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“…An even larger effect of the nuclear structure correction coming from the polarizability is expected in muonic atoms, as the muon mass is larger than the electron mass and the orbital radius is smaller. This will be relevant to the proposed μ 4 He and μ 3 He experiments [7] that aim at measuring the nuclear charge radius of 4 He and 3 He from the Lamb shift, to be compared to electron scattering data.…”

Section: Introductionmentioning

confidence: 99%

Nuclear electric polarizability of6He

2012

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We present an estimate of the nuclear electric polarizability α E of the 6 He halo nucleus based on sixbody microscopic calculations. Wave functions are obtained from semirealistic two-body interactions using the hyperspherical harmonics expansion method. The polarizability is calculated as a sum rule of the dipole response function using the Lanczos algorithm and also by integrating the photoabsorption cross section calculated via the Lorentz integral transform method. We obtain α E = 1.00(14) fm 3 , which is much smaller than the published value α exp E = 1.99(40) fm 3 [Pachucki and Moro, Phys. Rev. A 75, 032521 (2007)] extracted from experimental data. This points toward a potential disagreement between microscopic theories and experimental observations.

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Section: Introductionmentioning

confidence: 99%

Nuclear electric polarizability of6He

2012

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“…11,12 The experiment is performed at the high intensity proton accelerator facility at Paul Scherrer Institute in Switzerland. Its purpose was to measure the different 2S → 2P transitions in the µ The accelerator physics environment leads to stringent demands on stability and robustness of the APDs and the analysis routine employed that exceed common specifications.…”

Section: Appendix: the µHe Lamb Shift Experimentsmentioning

confidence: 99%

“…In addition, we were able to identify background signals stemming from electrons that deposit a few keV energy in the APD. The data presented in this work were gathered in the muonic helium Lamb shift experiment, 11,12 using a set of twenty large area avalanche photodiodes (LAAPDs) from radiation monitoring devices (model S1315; 13.5 × 13.5 mm 2 active surface area each). The muonic helium ions represent an extended x-ray source that emits predominantly monoenergetic x-rays of 1.52 keV and 8.22 keV as well as electrons with up to 50 MeV of kinetic energy (see the Appendix).…”

Section: Introductionmentioning

confidence: 99%

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Improved x-ray detection and particle identification with avalanche photodiodes

Diepold

Fernandes

Machado

et al. 2015

Review of Scientific Instruments

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Avalanche photodiodes are commonly used as detectors for low energy x-rays. In this work, we report on a fitting technique used to account for different detector responses resulting from photoabsorption in the various avalanche photodiode layers. The use of this technique results in an improvement of the energy resolution at 8.2 keV by up to a factor of 2 and corrects the timing information by up to 25 ns to account for space dependent electron drift time. In addition, this waveform analysis is used for particle identification, e.g., to distinguish between x-rays and MeV electrons in our experiment. C 2015 AIP Publishing LLC. [http://dx

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“…Results for the 2S-6S/D transitions measured at the National Physical Laboratory [62], which are currently being analysed, may bring an important and independent contribution to the hydrogen spectroscopy and so to the proton radius puzzle. Combined with the ongoing experiment at Garching, which is aimed at measuring the 1S-2S transition in He + [63], the experiment planned at the Paul Scherrer Institute to measure the muonic helium ion Lamb shift (mHe + ) may illuminate the proton radius conundrum [64]. A determination of the [58], (e) from Berkeland et al [59], (f ) from Bourzeix et al [60] combined with Arnoult et al [53], (g) from de Beauvoir et al [24], (h) from Schwob et al [61], and (i) from Arnoult et al [53]).…”

Section: (D) Rydberg Constantmentioning

confidence: 99%

Is the proton radius a player in the redefinition of the International System of Units?

Nez

Antognini

Amaro

et al. 2011

Phil. Trans. R. Soc. A.

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International audienceIt is now recognized that the International System of Units (SI units) will be redefined in terms of fundamental constants, even if the date when this will occur is still under debate. Actually, the best estimate of fundamental constant values is given by a least-squares adjustment, carried out under the auspices of the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants. This adjustment provides a significant measure of the correctness and overall consistency of the basic theories and experimental methods of physics using the values of the constants obtained from widely differing experiments. The physical theories that underlie this adjustment are assumed to be valid, such as quantum electrodynamics (QED). Testing QED, one of the most precise theories is the aim of many accurate experiments. The calculations and the corresponding experiments can be carried out either on a boundless system, such as the electron magnetic moment anomaly, or on a bound system, such as atomic hydrogen. The value of fundamental constants can be deduced from the comparison of theory and experiment. For example, using QED calculations, the value of the fine structure constant given by the CODATA is mainly inferred from the measurement of the electron magnetic moment anomaly carried out by Gabrielse's group. (Hanneke et al. 2008 Phys. Rev. Lett. 100, 120801) The value of the Rydberg constant is known from two-photon spectroscopy of hydrogen combined with accurate theoretical quantities. The Rydberg constant, determined by the comparison of theory and experiment using atomic hydrogen, is known with a relative uncertainty of 6.6 x 10(-12). It is one of the most accurate fundamental constants to date. A careful analysis shows that knowledge of the electrical size of the proton is nowadays a limitation in this comparison. The aim of muonic hydrogen spectroscopy was to obtain an accurate value of the proton charge radius. However, the value deduced from this experiment contradicts other less accurate determinations. This problem is known as the proton radius puzzle. This new determination of the proton radius may affect the value of the Rydberg constant R-infinity. This constant is related to many fundamental constants; in particular, R-infinity links the two possible ways proposed for the redefinition of the kilogram, the Avogadro constant N-A and the Planck constant h. However, the current relative uncertainty on the experimental determinations of N-A or h is three orders of magnitude larger than the 'possible' shift of the Rydberg constant, which may be shown by the new value of the size of the proton radius determined from muonic hydrogen. The proton radius puzzle will not interfere in the redefinition of the kilogram. After a short introduction to the properties of the proton, we will describe the muonic hydrogen experiment. There is intense theoretical activity as a result of our observation. A brief summary of possible theoretical explanations at the date of writing of the pap...

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Illuminating the proton radius conundrum: the μHe⁺ Lamb shiftThis 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.

Cited by 72 publications

References 38 publications

Nuclear electric polarizability of6He

Nuclear electric polarizability of6He

Improved x-ray detection and particle identification with avalanche photodiodes

Is the proton radius a player in the redefinition of the International System of Units?

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Illuminating the proton radius conundrum: the μHe+ Lamb shiftThis 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.

Cited by 72 publications

References 38 publications

Nuclear electric polarizability of6He

Nuclear electric polarizability of6He

Improved x-ray detection and particle identification with avalanche photodiodes

Is the proton radius a player in the redefinition of the International System of Units?

Contact Info

Product

Resources

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Illuminating the proton radius conundrum: the μHe⁺ Lamb shiftThis 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.