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Feb 16, 2024

How Small is a Proton? Smaller Than Anyone Thought

Posted by in category: particle physics

The proton, that little positively-charged nugget inside an atom, is fractions of a quadrillionth of a meter smaller than anyone thought, according to new research appearing Nov. 7 in Nature.

In work they hope solves the contentious “proton radius puzzle” that has been roiling some corners of physics in the last decade, a team of scientists including Duke physicist Haiyan Gao have addressed the question of the proton’s radius in a new way and discovered that it is 0.831 femtometers across, which is about 4 percent smaller than the best previous measurement using electrons from accelerators. (Read the paper!)

A single femtometer is 0.000000000000039370 inches imperial, if that helps, or think of it as a millionth part of a billionth part of a meter. And the new radius is just 80 percent of that.

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