Two nuclei with the same number of particles but different neutron skin shapes collide at speeds close to the speed of light. Ruthenium-96 and zirconium-96 are like twins, one with a slightly thicker coat. This difference changes how particles carry charge in the fireball of the collision.
Scientists used the UrQMD model to simulate collisions and compared with STAR detector data. They varied the proton surface diffuseness parameter for zirconium and found the best match for the net charge difference ΔQ. It turned out that the neutron skin noticeably changes the ratio of baryon charge transport to charge $R_B$/Q. This explains why in central collisions $R_B$/Q is greater than one, even without the baryon junction hypothesis.
The neutron skin of zirconium-96 is thicker than that of ruthenium-96, even though they have the same number of neutrons and protons.