Imaging the structure of atomic nuclei in high-energy nuclear collisions from STAR experiment

TL;DR

This paper introduces a novel method to image nuclear shapes in high-energy collisions, revealing detailed nuclear deformation properties and neutron skin differences, which enhances understanding of initial conditions in quark-gluon plasma studies.

Contribution

The paper demonstrates the first quantitative nuclear shape imaging technique using collective flow data from RHIC collisions, providing new insights into nuclear deformation and structure.

Findings

Identified quadrupole deformation and triaxiality in $^{238}$U

Detected moderate quadrupole deformation in $^{96}$Ru

Observed large octupole deformation in $^{96}$Zr

Abstract

In relativistic heavy-ion collisions, the extractions of properties of quark-gluon plasma (QGP) are hindered by a limited understanding of its initial conditions, where the nuclear structure of the colliding ions play a significant role. In these proceedings, we present the first quantitative demonstration using ``collective flow assisted nuclear shape imaging" method to extract the quadrupole deformation and triaxiality from $^{238}$U using data from the Relativistic Heavy Ion Collider (RHIC). We achieve this by comparing bulk observables in $^{238}$U+$^{238}$U collisions with nearly spherical $^{197}$Au+$^{197}$Au collisions. A similar comparative measurement performed in collisions of $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr, suggests the presence of moderate quadrupole deformation of $^{96}$Ru, large octupole deformation of $^{96}$Zr, as well as an apparent neutron skin difference between these two species. The prospect of this nuclear shape imaging method as a novel tool for the study of nuclear structure is also elaborated.