Magnetic Moment Of Proton Research Articles

A Proposed Method of Measuring γ́p in Terms of the Quantum of Magnetic Flux: A Route to α

The paper discusses a method for measuring the gyromagnetic ratio of protons in a spherical water sample in terms of the quantum of magnetic flux. Combining this quantity with more accurately determined constants: the proton magnetic moment in terms of the Bohr magneton, and the Rydberg constant, as well as the velocity of light, would yield an improved experimental value for the fine-structure constant.

Reproduction of the ampere from the proton gyromagnetic ratio and quantum magnetoresonance phenomena

Reproduction of the ampere from the proton gyromagnetic ratio and quantum magnetoresonance phenomena

Are the N and Δ deformed MIT bags?

The influence of the one-gluon exchange interaction, zero-point energy, and centre-of-mass correction, on the deformation of the nucleon and Δ bags, is studied in the MIT bag model. If the sharp MIT boundary conditions are taken seriously, the strong dependence of the zero-point energy on the deformation leads to the collapse of the N and Δ bags for realistic values of the strong fine structure constant αS. If on the other hand the zero-point energy is ignored altogether, then the nucleon, spherical for αS 3.25, while the Δ is always prolate. The various predictions of the model are, for αS >~ 3.25, consistent with experiment, except for the proton magnetic moment which is only about 40% of the experimental value.

Molecular dynamics in solid 1,4-diazabicyclo[2.2.2]octane perchlorate and hemiperchlorate

The temperature dependence of the proton magnetic resonance second moments, spin-lattice relaxation times T 1 and the calorimetric behaviour of polycrystalline 1,4-diazabicyclo[2.2.2]octane perchlorate and hemiperchlorate have been determined. The proton second moments show that the structure is rigid on the N.M.R. time scale at the lowest temperatures studied but that, at higher temperatures, the molecule executes uniaxial rotation about the N-N axis. Analysis of the relaxation data yields an activation energy for this motion of 46·6 ± 5 kJ mol-1 and 9·6 ± 2 kJ mol-1 for the perchlorate and the hemiperchlorate, respectively. An additional process involving C3 ⇌ C3ν ⇌ C3 intramolecular motion has been invoked to explain a slight reduction of the second moment and the appearance of a new, sharp, line in the centre of the proton spectrum above the II → I phase transition. Both the spectrum and the relaxation data are in agreement with the calorimetric results.

Centre-of-mass motion effects in static properties of baryons

Effects due to the centre-of-mass motion in the static properties of baryons (theGA/Gv value, the proton magnetic moment, the mean square radius of the proton charge, andA(1) andA(2) constants appearing in the nonleptonic decays of baryons) are examined for some kinds of mean-field confining potentials. Certain indications about the potential form are obtained in order to get favourable values of the mean square radius as well asA(1) andA(2) constants.

Electromagnetic pion pair current from quark models.

The pionic pair current is calculated from bag and constituent quark models which include a two-quark pion exchange potential. Except for form factors from the large Dirac-quark wave function, the result agrees with conventional nuclear theory. Gauge invariance is maintained. From the pion quark-pair and exchange currents inside a nucleon, a corresponding contribution to the proton and neutron magnetic moments is calculated.

The proton enigma

It is suggested that the proton and neutron magnetic moments can be calculated by a theory involving a standing wave systems centered on the proton. (AIP)

Report on the New NBS Determination of the Proton Gyromagnetic Ratio

We describe a new measurement of the proton gyromagnetic ratio in H2O, ??p, now in progress at NBS, including the construction of a single layer precision solenoid, the measurement of its dimensions by an inductive technique, and our latest dimensional measurement results. We also discuss other improvements made since our last ??p determination.

Mass formula for Z0 and other predictions

The mass formulaMz= 2(Mpα)(1/gc = 92.1 GeV is derived, whereMp is the proton mass, χ= 2.79 the proton magnetic moment, and α−1 = 137.

The Dirac equation and its solutions for quarks confined by an SO(3,2)-invariant geometry

Exact solutions for relativistic spinor fields in a baglike representation of anti---de Sitter geometry are given. It is shown that the equal energy separation of radial excitations in the meson spectra can be explained in a natural way. Moreover, a satisfactory proton magnetic moment is obtained.

Magnetic moments of confined quarks and baryons in an independent-quark model based on Dirac equation with power-law potential

The effect of confinement on the magnetic moment of a quark has been studied in a simple independent-quark model based on the Dirac equation with a power-law potential. The magnetic moments so obtained for the constituent quarks, which are found to be significantly different from their corresponding Dirac moments, are used in predicting the magnetic moments of baryons in the nucleon octet as well as those in the charmed and $b$-flavored sectors. We not only get an improved result for the proton magnetic moment, but the calculation for the rest of the nucleon octet also turns out to be in reasonable agreement with experiment. The overall predictions for the charmed and $b$-flavored baryons are also comparable with other model predictions.

Proton and neutron magnetic moments from QCD sum rules

The proton and neutron magnetic moments are calculated within QCD using sum rules with bilocal power corrections accounted for.

On the axial charge and other static properties of the quark core in nucleons

We present calculations of the axial vector constant g A in models where relativistic quarks are confined by scalar potentials, with special emphasis on center-of-mass corrections and pion cloud effects. It is demonstrated that pionic contributions to g A from a f π ϑ μ φ term in the axial current vanish for finite pion mass. Confining potentials of the form cr n with n = 2, 3 give acceptable values for g A together with quark core radii between 0.5 and 0.6 fm. We also calculate the pion-nucleon coupling constant and establish a connection between g A and the quark core part of the magnetic moment, including center-of-mass corrections. About half of the proton magnetic moment is shown to come from the quark core.

A mechanism for the para-ortho conversion of hydrogen by diamagnetic substances

Various thories for the conversion are considered. The role of internal electric fields can be seen by comparing the rates of experimentally observed conversion reactions for hydrogen in simple liquids. The magnetic field due to the proton magnetic moment is the same magnitude. The p-o conversion is shown to be caused by paramagnetic centers, but not in all cases.

The proton and neutron magnetic moments in lattice QCD

We have computed the proton and neutron magnetic moments on the lattice by a Monte Carlo simulation of QCD in the quenched approximation. The results are in remarkable agreement with the experimental values.

Second moment in wide-line proton magnetic resonance and its relation to packing density of protons in the unit cell

Analysis of the proton magnetic resonance second moment data of more than 60 organic and biological compounds has been carried out. It is shown that with certain classification schemes, such as compounds involving groups of protons (triplets and doublets), the second moment exhibits an approximate linear correlation with the proton density in the unit cell, defined as the number of protons per unit volume in the particular packing adopted by the structure.

Ay(θ)forp→+Pb208elastic scattering at 0.8 GeV and a test of multiple scattering theory

New, large-momentum-transfer 0.8 GeV p+/sup 208/Pb elastic analyzing power data are presented and compared to optical model predictions using the Kerman-McManus-Thaler microscopic optical potential. This comparison provides an important test of multiple scattering theories since the predictions are quite sensitive to the assumed nucleon-nucleon scattering amplitudes and are not sensitive to the details of the nuclear densities. We show that improvement in the agreement between experiment and a parameter-free theoretical prediction is obtained when the calculation includes the electromagnetic spin-orbit potential which arises from the coupling of the projectile proton's magnetic moment and the Coulomb field of the target nucleus. The sensitivity of the predicted analyzing power to the various ingredients of the theory is also investigated, and the importance of the inclusion of target-nucleon correlations (in the second-order Kerman-McManus-Thaler potential) for proper explanation of the data is discussed.

A New Method for the Accurate Determination of the Proton Gyromagnetic Ratio

Accurate knowledge of the value of the proton gyromagnetic ratio γ́p is of great interest due to its role in the determination of the value of the fine structure constant. In this paper, a new technique for the determination of γ́p is proposed which employs the Ramsey separated oscillatory field magnetic resonance technique using flowing water. Systematic effects and possible sources of error are discussed. The method may be capable of an accuracy of a few parts in 108. This would provide an order of magnitude reduction in the uncertainty in α.

The electric and magnetic moments of the neutron

It is well known that the free neutron decays spontaneously into a proton, an electron and an antineutrino, that it has a spin of 1/2 h and a negative magnetic moment, but very careful measurements have failed as yet to reveal any evidence for a finite electric charge or dipole moment. This paper contains a brief discussion of early work and more detail of recent experiments at the Institut Laue-Langevin (I.L.L.), Grenoble, which have shown that the neutron charge is probably less than 4 x 10 -20 electron charges (Bayreuth-Munich group), the neutron electric dipole moment (e.d.m.) is less than 1.5 x 10 -24 cm times the electron charge (Oak Ridge-Harvard-Sussex group), and the ratio of the neutron and proton magnetic moments is equal to — 0.68497 947(17), the uncertainty being only 0.25/10 6 (Harvard-Sussex-Oak Ridge group). The main features of the Leningrad experiments with ultra-cold neutrons, which have reduced the neutron electric dipole length to 7.5 x 10 -25 cm, are reported, with some details of the performance of the ultra-cold neutron magnetic resonance spectrometer now working at I.L.L. and the way it will be used to look for a neutron e.d.m. The paper concludes with some comments on the importance of the neutron moments to the development of the theory of fundamental particles.

Forthcoming Conference on Fundamental Constants

The Second International Conference on Precision Measurement and Fundamental Constants will be held 8–12 June 1981 at the National Bureau of Standards (NBS), Gaithersburg, Maryland. This Conference will be similar to that held at NBS Gaithersburg in August 1970: It will provide an international forum for those engaged in experimental and theoretical research on precision measurements relating to the fundamental physical constants, and on the testing of related fundamental theory. The topics of interest include: High accuracy mass measurements and the kilogram Absolute realizations of the basic electric units Frequency and time standards Frequency measurements of optical radiation, the speed of light and the unit of length Faraday and Avogadro constants Proton gyromagnetic ratio Proton magnetic moment in Bohr and nuclear magnetons Fine and hyperfine structure in simple atoms such as hydrogen, muonium, positronium and helium Rydberg constant Proton to electron mass ratio Lepton magnetic moment anomalies Fine-Structure constant High precision tests of QED Newtonian gravitational constant and gravitational acceleration Eötvös experiments, anisotropy of space, high precision tests of relativity Gas and Stefan-Boltzmann constants Time variation of the constants Assignment of uncertainties to determinations of constants Lease-squares adjustments of the constants. It is expected that new results reported at the Conference will be considered for inclusion in the next least-squares adjustment of the constants which is being carried out under the auspices of the CODATA Task Group on Fundamental Constants. This adjustment should be completed by the end of 1981 and the resulting set of recommended values officially adopted for international use by CODATA in early 1982.Those interested in the Conference should communicate with Dr B N Taylor, National Bureau of Standards, Building 220, Room B 258, Washington, DC 20234, USA.