The Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) smashed together large nuclei at nearly the speed of light to recreate the fundamental particles in the primordial soup present during the earliest days of the universe.
In a study published in the Physical Review Letters, researchers confirmed that experiments at the RHIC have shown that the quark-gluon plasma (QGP), the primordial soup, flows like an almost friction-free perfect liquid. This also validates earlier suspicion that colliding smaller particles with large nuclei can lead to primordial soup droplets being made, although on a smaller scale.
"These tiny droplets of quark-gluon plasma were at first an intriguing surprise," said Berndt Mueller, Nuclear and Partcile Physics associate laboratory director from the BNL, adding that physicists thought initially that just the nuclei of large atoms like gold will have enough energy and mass to free the building blocks of gluon and quark making up neutrons and protons. But based on flow patterns recorded by the PHENIX collaboration at the RHIC, gold ions and helium-3 nuclei colliding leads to tiny samples of QGP.
The results of the current research builds upon earlier findings derived after colliding gold with two-particle ions called deuterons, proton with proton and proton with lead at the Large Hadron Collider.
The RHIC's discovery of the QGP was mostly based on observations that showed particles flowed in an elliptical pattern from the resulting matter produced by the collider's most energetic collisions involving gold and gold. Aside from the flow being a clear sign that emerging particles from collisions behaved in a collective or correlated way that dramatically goes against gas expanding uniformly, the researchers also confirmed that the produced liquid was indeed made up of the most fundamental components of gluons, quarks and building blocks of visible matter; not confined within individual neutrons and protons and moved with little resistance.
If other models offer compatible results with data from helium 3 and gold collisions, physicists should be expected to explore what these models have to offer, assessing if they can make predictions different from the hydrodynamic flow model and for which kinds of collisions.
The good news is, according to Mueller, that the RHIC has no competition when it comes to versatility, making it capable of studying any kind of system that discriminates between models.
RHIC research receives funding support primarily from the U.S. Department of Energy.