Suffolk Reporter

Scientists at the Relativistic Heavy Ion Collider (RHIC) have developed a new method to study atomic nuclei shapes through high-energy particle collisions. This technique, recently detailed in Nature, complements existing lower energy methods and offers insights into nuclear structure.

Jiangyong Jia from Stony Brook University explained, "In this new measurement, we not only quantify the overall shape of the nucleus — whether it’s elongated like a football or squashed down like a tangerine — but also the subtle triaxiality." This approach can reveal information about both protons and neutrons within nuclei, unlike traditional low-energy experiments that mainly capture proton arrangements over longer timescales.

Chun Shen from Wayne State University likened previous methods to "taking a long-exposure picture," which fails to capture fast timescale variations. The new high-energy imaging method is significantly faster and provides more detailed snapshots of nuclear structures.

The RHIC team analyzed particle flow and momentum from collisions to infer nuclear shapes. They compared gold and uranium nuclei collisions, observing variability in uranium due to its oblong shape. Shengli Huang noted that "central collisions of gold nuclei produce a circular, fixed size QGP that expands evenly in all directions."

Computational models played a crucial role in interpreting data from these experiments. Chunjian Zhang used over 20 million CPU hours on the Open Science Grid for calculations. He stated, "Many features in the STAR data are indicative of significant differences in shape between the uranium and gold nuclei."

This research may enhance understanding of quark-gluon plasma (QGP) conditions at RHIC and Europe's Large Hadron Collider (LHC). It could also help reduce uncertainties about initial state conditions in heavy ion collisions.

The study's implications extend beyond immediate findings. Jia highlighted interdisciplinary impacts: "Nuclear physics has many subfields... Several workshops, meetings, and conferences were organized to explore connections between high-energy and low-energy frontiers."

Support for this work came from various sources including the DOE Office of Science, U.S. National Science Foundation (NSF), international agencies, and computing resources like Brookhaven Lab's Scientific Data Center.