Physicists have made the most high-precision measurements of the magnetic moment of the proton

Physicists have made the most high-precision measurements of the magnetic moment of the proton

A group of physicists from Japan and Germany conducted a series of experiments, the data of which allowed them to calculate the magnitude of the magnetic moment of a proton with the highest accuracy to date. According to available data, the magnetic moment of the proton is 2.79284734462 ± 0.00000000082 nuclear magnetons, the units in which the magnetic moment is measured.

Note that knowing the exact value of this parameter is of great importance for modern physics, because the magnetic moment is the basis of particle magnetism, on which the structure and properties of atoms depend, for example.

Image of a proton captured by magnetic fields © RIKEN

Image of a proton captured by magnetic fields

The high-precision measurements required very painstaking work, during which scientists isolated one, two and three separate protons inside the Penning trap. A unique way of moving a single proton from one trap to another was also developed.

The measurements were based on the fact that the spin, the angular momentum of the proton in the trap, aligns in accordance with the direction of the magnetic field of the trap itself. One of the sensors measured the so-called Larmor frequency, which depends on the spin of a particle placed in a magnetic field. And the second measured frequency was the so-called cyclotron resonance frequency of the proton. The measurements of these two frequencies were made in two different traps, in each of which sensors were installed based on different physical principles.

Physicists make most precise measurement ever of the proton's magnetic moment

The Penning Trap © RIKEN

It is this approach, carrying out separate measurements in two traps, that made it possible to obtain the highest accuracy of frequency measurements. A large number of measurement cycles, which amounted to 1,264 cycles, contributed to the increase in accuracy. The duration of each cycle is about 90 minutes and the whole series of measurements took four months of time, including the time for servicing and recalibrating the measuring equipment.

“This work gave us a new way of high-precision measurements of the magnetic moment of elementary particles” – says Georg Schneider, lead researcher, – “In the near future, we plan to make similar measurements of the antiproton magnetic moment. Now antiprotons are produced by the equipment of the BASE experiment of the European Organization for Nuclear Research CERN, and their research will allow us to understand some of the subtleties of the structure of atoms, plus we can get some clues as to why there is almost no antimatter in the modern Universe. “

Adapted from
The article was published in the journal Science


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