To study atomic nuclei and subatomic particles, scientists use the Large Hadron Collider (LHC) to collide heavy ions—atomic nuclei completely stripped of their surrounding electrons. In these collisions, the quarks and gluons that normally make up nucleons (protons and neutrons) melt into a new state of matter called a quark-gluon plasma (QGP).
Click here for original story, Nucleons in heavy ion collisions are half as big as previously expected
Source: Phys.org