Lone Proton

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Science  14 May 2010:
Vol. 328, Issue 5980, pp. 795
DOI: 10.1126/science.328.5980.795-a

A small test mass attached to a spring and driven to oscillate will furnish information on the mechanical properties of the spring itself and also the medium in which it is immersed. In a similar fashion, probing the oscillation frequency of a single trapped electron provides knowledge of the magnetic moment of the electron (the test mass) as well as a precise knowledge of its electromagnetic environment by way of the fine structure constant. As matter is made up of electrons, protons, and neutrons, it seems natural to ask how the magnetic properties of all the elementary particles arise. However, because the magnetic properties of nucleons are much weaker than those of electrons, correspondingly precise measurements become very challenging. Hoping to change that situation, Guise et al. have developed a technique to trap and probe a single proton (or antiproton). The asymmetries between matter and antimatter can also be addressed in this context at the fundamental level.

Phys. Rev. Lett. 104, 143001 (2010).

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