Bowling Near the Speed of Light
Collisions of lead with smaller nuclei allow taking images of the fluctuating nuclear shape
The Science
Protons and neutrons are composed of quarks and gluons, which are “confined” inside of the protons and neutrons. When heavy ions collide at high speeds, they create a quark-gluon plasma (QGP). In the QGP, the quarks and gluons are no longer confined. In this work, scientists studied fixed-target collisions between large lead-208 nuclei and smaller neon-20 nuclei. The neon-20 has the shape of a “bowling-pin.” This unusual shape produces clear patterns of how particles flow after the collision. These flow signals provide new evidence for the formation of the QGP in these collisions. They also reveal a new way to study the detailed shapes of atomic nuclei.
The Impact
This research demonstrates that nuclear shapes leave a fingerprint of how particles flow in heavy-ion collisions. The unusual structure of neon-20 leads to distinctive patterns in these collisions that the LHCb experiment at CERN can measure. These findings help scientists test ideas about how nuclear structure connects to the creation of QGP. They also show how experiments that shoot a beam at a fixed target can explore QGP in a new set of beam energies and densities. These experiments can give further insights into how matter behaved in the early universe. This cross-disciplinary approach links nuclear structure theory with high-energy physics, creating a new tool for imaging the shapes of nuclei.
Summary
An international collaboration of researchers combined nuclear structure theory with hydrodynamics simulations of heavy-ion collisions. They used ab initio calculations based on both continuum and lattice methods to describe the structure of neon-20 and then simulated its collisions with lead-208. The simulations predicted strong elliptic and quadrangular flow signals that directly reflect the shape of neon-20. These results can soon be tested with fixed-target data from the LHCb experiment at CERN. The study shows how ab initio nuclear theory and relativistic heavy-ion physics can be joined to reveal both the properties of QGP and the shapes of atomic nuclei.
Contact
Dean Lee
Facility for Rare Isotope Beams
leed@frib.msu.edu
Funding
Funding is from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), U.S. Department of Energy (DOE) Office of Science’s Office of Nuclear Physics, U.S. National Science Foundation European Research Council (ERC) Spanish MCIU. The study used computing resources GENCI-TGCC, the Gauss Centre for Supercomputing e.V., the Oak Ridge Leadership Computing Facility (a DOE Office of Science User Facility), and the TUBITAK ULAKBIM High Performance and Grid Computing Center.
Publications
G. Giacalone et al., “Anisotropic Flow in Fixed-Target 208Pb + 20Ne Collisions as a Probe of Quark-Gluon Plasma,” Physical Review Letters 134, 082301 (2025). DOI: 10.1103/PhysRevLett.134.082301
Highlight Categories
Program: NP
Performer: FRIB
Additional: International Collaboration
