Scientists have measured the accurate size of a proton
Now, scientists suggest that the earlier measurements of proton size were off by 5 per cent.
Protons are the parts of an atom. Electrons, protons, and neutrons are found in the nucleus of an atom. Even though we know various properties of the proton including mass, charge, and size of the particle, a debate related to its size started in 2010 because a team of physicists measured the proton radius value and discovered it to be four percent smaller than expected. This puzzle is close to getting solved as scientists have found a new value for the size of a proton.
Now, scientists suggest that the earlier measurements of proton size were off by 5 per cent. The team of researchers based in Canada are suggesting the new value of the radius of a proton is around 0.833 femtometres (1 femtometer equals 10 to power minus 15 meter). Slightly off from the number of 0.842 femtometres which was calculated in 2010.
One of the physicists from New York University Eric Hessels says, "The level of precision required to determine the proton size made this the most difficult measurement our laboratory has ever attempted." He also added, "After eight years of working on this experiment, we are pleased to record such a high-precision measurement that helps to solve the elusive proton-radius puzzle."
In our imaginations, protons are small little ball-like spheres inside the nucleus. But scientists suggest that protons are not as smooth as spheres, as they lack a distinct surface and are defined by a threshold in their positive charge.
There are two methods used to measure the extent of the boundary of a proton. The first method shoots negatively charged particles at the nuclei of hydrogen atoms and watches how it rebounds from a surface. The second method tries to understand the boundary of a proton through quantum mechanics. It suggests that the particles don't always have a clear position.
Quantum mechanics suggest that electrons occasionally find themselves in the dead heart of a proton. Nobel laureate Wallis Lamb quantified the difference in energy states of an excited electron around 70 years ago. This time, scientists used a new method called FOSOF – short for frequency-offset separated oscillatory fields – that helped in measuring the size of a proton. The new method provided the extra precision required.
The research took eight years to complete and highlights that protons are not as big as we'd once imagined.