According to research published in Physical Review Letters in August 2026, scientists using the CMS detector at the CERN Large Hadron Collider analyzed high-energy oxygen-oxygen and neon-neon collisions at 5.36 TeV per nucleon pair to reveal new details about nuclear geometry. The study observed significant long-range collective flow, helping physicists probe the internal arrangements of lighter nuclei.
Probing Nuclear Structure with Oxygen and Neon Collisions
Lighter nuclei such as oxygen and neon offer a cleaner test of collision geometry than heavy nuclei like uranium or proton-based collisions. The researchers noted that symmetric light-ion collisions deliver superior management over the starting geometry of the collision because this is dictated chiefly by how nucleons are spatially distributed rather than the proton’s partonic framework.
Previous calculations regarding nuclear structure suggested that oxygen-16 features a tetrahedron-shaped core, whereas neon-20 adopts a stretched, bowling-pin configuration. Because the two ions share similar mass numbers, they experience similar hydrodynamic evolution.
Did you know? The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator, enabling scientists to recreate conditions similar to those just after the Big Bang by smashing atomic nuclei together at nearly the speed of light.
Flow Patterns and Centrality in CMS Detector Measurements
The research team analyzed collision data gathered by the CMS detector at CERN. Results demonstrated significant elliptic and triangular collective flow in both oxygen-oxygen and neon-neon collisions. These flow patterns shifted depending on how centrally the nuclei collided, acting like a fluid responding directly to the initial shape of the collision.
In the most head-on collisions, neon exhibited a stronger elliptic-flow signal than oxygen. This rising neon-to-oxygen elliptic-flow ratio aligns qualitatively with the expectation that neon-20 possesses a less spherical internal structure than oxygen-16. However, the triangular flow did not match quantitative predictions, moving in the opposite direction toward central collisions.
Theoretical Challenges and Future Analysis
While the findings demonstrate that high-energy collisions can probe nuclear structure through flow characteristics, they do not yet yield a precise measurement of neon’s deformation. Translating flow measurements into an exact nuclear shape requires further dedicated analysis. According to the study authors, none of the three model calculations fully reproduced the measured triangular flow ratios, highlighting the need for an improved treatment of initial-state fluctuations in small collision systems.
Pro Tip: When studying high-energy nuclear physics, researchers look at harmonic flow coefficients like $v_2$ and $v_3$ to decode the spatial geometry of colliding atomic nuclei before the quark-gluon plasma expands.
Frequently Asked Questions
What was discovered in the LHC oxygen and neon collisions?
Why use oxygen and neon instead of heavier elements?
Lighter nuclei offer better control over initial collision geometry because they are determined by nucleon spatial distribution rather than complex proton partonic structures.
What remains unresolved by the latest study?
While elliptic flow matches expectations for a deformed neon nucleus, triangular flow measurements do not match current quantitative models, requiring improved treatment of initial-state event fluctuations.
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