Heavyion

A heavy ion is an atomic nucleus with a relatively large mass number, used in nuclear and high-energy physics to study strongly interacting matter. Unlike light ions such as protons or deuterons, heavy ions consist of many protons and neutrons. Common examples include gold-197, lead-208, xenon-129, and uranium-238, which are selected for their large nucleon content and charge.

In high-energy collisions, heavy ions are accelerated to near-light speeds and smashed together in particle accelerators to create extreme temperatures and densities. The primary aim is to study the properties of nuclear matter under these conditions and to search for the quark-gluon plasma, a state in which quarks and gluons are not confined within hadrons. Observables from these experiments include collective flow patterns, jet quenching (suppression of high-energy jets), and enhanced production of strange quarks, all of which inform estimates of the medium’s temperature, density, and transport properties.

Heavy-ion research has been conducted at several major facilities. Early programs operated at CERN's Super Proton Synchrotron and later at the Large Hadron Collider, as well as at Brookhaven National Laboratory's Relativistic Heavy Ion Collider. Experimental collaborations such as ALICE, ATLAS, and CMS at the LHC have contributed to the field, along with RHIC experiments. Through these programs, physicists aim to understand quantum chromodynamics in the non-perturbative regime and the behavior of matter at extreme conditions.