The proton has a new radius • The register

The positively charged proton located inside the nucleus of atoms has a radius less than one trillion millimeter, according to an article published Thursday in Science.

The scientists scratched themselves the size of the proton. Different methods used to measure the radius of the subatomic particle produced different numbers, which some have dubbed the proton ray puzzle. The latter study concluded that its radius was only 0.833 femtometers, which is 8.33 x 10.^-16 meters.

"The level of precision required to determine the size of the proton was the most difficult step ever undertaken by our lab," said Eric Hessels, co-author of the journal and professor at the department of physics and astronomy York University in Canada.

The number of 0.833 femtometers is quite close to an earlier estimate of 0.840 femtometers achieved by another group of heads in 2013. It is however about 5% lower than the current official value of 0.876 femtometers.

"The difference between the proton size deduced from the Lamb shift in muonic hydrogen and the average value of a manual based on classical (electronic) hydrogen has baffled physicists for nearly a decade ", explains the summary of the document.

Measuring the Lamb shift in muonic hydrogen is a sophisticated experiment that allows scientists to pin down the size of the proton. First, the muons are orbited around the protons to create muonic hydrogen. It is an unstable arrangement and, as the structure disintegrates, an electron falls off two different energy levels, emitting a quantity of energy known as Lamb shift.

The difference in energy levels is affected by the interaction of the electron and the proton. By measuring Lamb offset, physicists can probe the properties of the proton. Physicists at York University and the University of Toronto in Canada spent eight years designing their own version of the proton ray experiment. ®

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