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The proton magnetic moment is the magnetic dipole moment of the proton, symbol ''μ''p. Protons and neutrons, both nucleons, comprise the nucleus of an atom, and both nucleons act as small magnets whose strength is measured by their magnetic moments. The magnitude of the proton's magnetic moment indicates that the proton is not an elementary particle. ==Description== The best available measurement for the value of the magnetic moment of the proton is .〔P.J. Mohr, B.N. Taylor, and D.B. Newell (2011), "The 2010 CODATA Recommended Values of the Fundamental Physical Constants" (Web Version 6.0). This database was developed by J. Baker, M. Douma, and S. Kotochigova. Available: http://physics.nist.gov/constants (02-Jun-2011 21:00:12 EDT ). National Institute of Standards and Technology, Gaithersburg, MD 20899.〕 By definition it is the z component of the spin magnetic moment of proton. 〔 Raymond Serway, John Jewett, "Principles of Physics: A Calculus-Based Text, Volume 2" https://books.google.co.in/books?id=ojcnccEZ780C&lpg=PP1&pg=PA1026#v=onepage&q&f=false.〕 Here ''μ''N is the nuclear magneton, a physical constant and standard unit for the magnetic moments of nuclear components. In SI units, . A magnetic moment is a vector quantity, and the direction of the proton's magnetic moment is defined by its spin. The torque on the proton resulting from an external magnetic field is towards aligning the proton's spin vector in the same direction as the magnetic field vector. The nuclear magneton is the spin magnetic moment of a Dirac particle, a charged, spin 1/2 elementary particle, with a proton's mass ''m''p. In SI units, the nuclear magneton is : where ''e'' is the elementary charge and ''ħ'' is the reduced Planck constant. The magnetic moment of this particle is parallel to its spin. Since the proton has charge +1 ''e'', it should have magnetic moment equal to 1 ''μ''N by this expression. The larger magnetic moment of the proton indicates that it is not an elementary particle. The sign of the proton's magnetic moment is that of a positively charged particle. Similarly, the fact that the magnetic moment of the neutron, , is finite and negative indicates that it too is not an elementary particle. Protons and neutrons are composed of quarks, and the magnetic moments of the quarks can be used to compute the magnetic moments of the nucleons. The magnetic moment of the antiproton is the same magnitude, but is of opposite sign, as that of the proton. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Proton magnetic moment」の詳細全文を読む スポンサード リンク
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