Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometre-scale space. The shape and orientation of colliding nuclei play a crucial role in determining the initial conditions of the quark–gluon plasma (QGP), which influence key observables such as anisotropic and radial flow. In this talk, I will present an “imaging-by-smashing” approach using soft probes that are directly sensitive to the structure of colliding nuclei, from large to small systems, in high-energy nuclear collisions [1,2,3]. We present the measurements of , fluctuation, and − correlations in isobar-like²³⁸U+²³⁸U and ¹⁹⁷Au+¹⁹⁷Au collisions at 193 and 200 GeV, respectively. Our results reveal prominent differences in these observables between the two systems, particularly in the most central collisions. We also present the first measurements of in ¹⁶O+¹⁶O and d+¹⁹⁷Au collisions, providing insight into the impact of nucleon–nucleon correlations and further shedding light on the initial conditions of QGP droplets. Comparisons with the state-of-the-art hydrodynamic calculations enable us to extract the nuclear shape parameters across energy scales [4,5]. This interdisciplinary research enhances our understanding of the initial conditions in high-energy collisions and provides new insights into the evolution of nuclear structure across energy scales.

References:
[1] STAR Collaboration, Nature 635, 67-72 (2024)

[2] STAR Collaboration, Rep. Prog. Phys. 88, 108601 (2025)

[3] STAR Collaboration, arXiv:2510.19645

[4] C. Zhang, J. Jia, J. Chen, C. Shen, L. Liu, arXiv:2504.15245

[5] C. Zhang, J. Chen, G. Giacalone, S. Huang, J. Jia, Y.-G. Ma, PLB862, 139322(2025)