German scientists measured the electron mass 13 times more accurately than before.

Electron is the first elementary particle known to man. It was discovered in 1897 by the British physicist Joseph John Thompson. Unlike many other particles, which previously seemed elementary, and then turned out to be composed of other particles, the electron is still considered to be one of the fundamental building blocks of the universe, and its mass and electric charge are among the main physical constants. Therefore, an accurate measurement of its mass is of great interest. Recently, a team of German physicists managed to break the record for measuring the mass of an electron.

An electron is a light particle, and measuring its mass directly is very difficult. Scientists used a highly ionized carbon atom, in which only one electron remained. The carbon ion was trapped in the Penning trap (in the photo) - a device for storing charged particles in a uniform magnetic field. Measuring the characteristics of a system consisting of the nucleus of a carbon atom and one electron, scientists were able to quite accurately determine the ratio of the mass of an electron to the nucleus of carbon-12. The mass of the carbon nucleus is very well known - it is a kind of benchmark: the atomic unit of mass, by definition, is equal to one-twelfth mass of the nucleus of a carbon atom.

The specified electron mass value is 0.000548579909067 amu. Usually an increase in the accuracy of measuring the mass of elementary particles by an order of magnitude is achieved in 10–20 years. This time, the accuracy was improved 13 times in just a few years after the previous record-high measurement of the electron mass.

An article describing the experiment was published in the journal Nature. Press release of the Max Planck Institute for Nuclear Physics at the University of Heidelberg (in German).
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