The Muon Scattering Experiment (MUSE) at PSI and the proton radius puzzle

Köhl, M.

doi:10.1051/epjconf/20148102008

Cited by 4 publications

(4 citation statements)

References 22 publications

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“…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.…”

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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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confidence: 99%

Hydrogen molecular ions for improved determination of fundamental constants

et al. 2016

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“…Finally, let us consider the introduction of the extraordinary claim on the existence of the n(o)-flux in the structure of the electromagnetic field of the elementary particles. As said Carl Sagan, extraordinary claims require extraordinary evidence, which perhaps will be discovered between 2018 and 2019, when the proton radius will be measured in the PSI proton accelerator (Kohl, 2014). Guglinski (2018) has calculated that proton radius, to be measured in the experiments, must be found between 0,62fm and 0,72fm.…”

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On how Bohr model of hydrogen atom is connected to nuclear physics

Guglinski

2018

IJFPS

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The atom model of Quantum Mechanics (QM) was conceived from an unsolved paradox. Indeed, Schrödinger's equation has been deducted by considering a free electron, but it is applied for the atom, where the electron is inside a potential. In order to eliminate the nonsense, quantum theorists proposed a ridiculous postulate: they claim it makes sense to use the equation because it gives results in agreement to experimental data. The unsolved paradox evidences that Schrödinger's equation cannot be applied to the physical conditions considered in the QM atom model, and that his equation actually requires some special conditions not considered in the theory (for instance, the electron helical trajectory, rejected by Heisenberg). The banishment of the aether has introduced several paradoxes in the development of Theoretical Physics. And because the theorists have neglected other paradox (from the mathematical probability the spectacular successes of Bohr's hydrogen atom cannot be accidental), these two unsolved paradoxes introduced dramatic consequences in the development of Nuclear Physics.

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“…Ultimately, the exact cause of this time-varying efficiency was not definitively identified, but seemed to be associated with the readout system of the GEMs and its behavior as a function of hit rate/beam conditions. This should be diligently kept in mind when considering the use of the OLYMPUS GEMs in future experiments [133,134].…”

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confidence: 99%

“…Six planes and two detector technologies were utilized to provide high resolution tracking of the high momentum forward events, and to provide a mechanism of cross-checks and calibration within the detector system. Ultimately, the GEM detectors were not used in the final luminosity analysis due to problems with the stability of their efficiencies (see Section 5.2.2), but were useful in the calibration of the system and are being considered for use in future experiments [133,134].…”

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confidence: 99%

A precision measurement of the e+p/e-p elastic scattering cross section ratio at the OLYMPUS experiment

Henderson¹

2017

Preprint

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Measurements of the ratio of the proton elastic form factors (µ p G E /G M ) using Rosenbluth separation and those using polarization-based techniques show a strong discrepancy, which has persisted both in modern experimental results and in re-analyses of previous data. The most widely accepted hypothesis to explain this discrepancy is the treatment of the contributions from hard two-photon exchange (TPE) to elastic electron-proton scattering in the radiative corrections applied to the Rosenbluth separation measurements. Calculations of the hard TPE contribution are highly model dependent, but the effect may be measured experimentally with a precise determination of the ratio of the positron-proton and electron-proton elastic scattering cross sections.The OLYMPUS experiment collected approximately 4 fb −1 of e + p and e − p scattering data at the DORIS storage ring at DESY in 2012, with the goal of measuring the elastic σ e + p /σ e − p ratio over the kinematic range (0.4 ≤ ≤ 0.9), (0.6 ≤ Q 2 ≤ 2.2) GeV 2 /c 2 at a fixed lepton beam energy of 2.01 GeV. The detector for the OLYMPUS experiment consisted of refurbished elements of the Bates Large Acceptance Spectrometer Toroid (BLAST) surrounding an internal gaseous hydrogen target, with the addition of multiple systems for the monitoring of the luminosity collected by the experiment. A detailed simulation of the experiment was developed to account for both radiative corrections and various systematic effects.This work presents preliminary results from the OLYMPUS data, demonstrating that the elastic σ e + p /σ e − p ratio rises to several percent at ≈ 0.4 and indicating a significant contribution from TPE to e ± p scattering. Additionally, the value of σ e + p /σ e − p has been measured to unprecedented precision at = 0.98, which provides a valuable normalization point for other experimental data.

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The Muon Scattering Experiment (MUSE) at PSI and the proton radius puzzle

Cited by 4 publications

References 22 publications

Hydrogen molecular ions for improved determination of fundamental constants

Hydrogen molecular ions for improved determination of fundamental constants

On how Bohr model of hydrogen atom is connected to nuclear physics

A precision measurement of the e+p/e-p elastic scattering cross section ratio at the OLYMPUS experiment

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