3-D View Of Quarks Inside Proton

Physicists are measuring how the most basic known building blocks of nature — quarks — are arranged to make up protons, key pieces of the atomic nucleus.  The findings could be a step toward eventually understanding the three-dimensional internal structure of protons and neutrons, the particles forming the heart of an atom.  It now turns out that the quarks take up positions that depend largely on the direction of their spin: those with opposite spin tend to find themselves in opposite sides of the proton.

New findings indicate that in a proton, quarks with spin in the up direction (red and blue) tend to gather in the left half of the proton as seen by an incoming electron. Down-spinning quarks (green) tend to gather in the right half.