# Stopping effects in U+U collisions with a beam energy of 520 MeV/nucleon

## TL;DR

This study uses a relativistic transport model to simulate uranium-uranium collisions at 520 MeV/nucleon, revealing how different orientations affect nuclear stopping, flow, and the potential to probe the nuclear equation of state.

## Contribution

It demonstrates the impact of uranium nucleus orientation on stopping effects and flow observables, providing insights for future experiments to study the nuclear EoS.

## Key findings

- Full stopping achieved in extreme collision orientations.
- Tip-tip collisions produce nearly three times larger sideward flow.
- Body-body collisions exhibit significant negative elliptic flow.

## Abstract

A Relativistic Transport Model (ART1.0) is applied to simulate the stopping effects in tip-tip and body-body U+U collisions, at a beam kinetic energy of 520 MeV/nucleon. Our simulation results have demonstrated that both central collisions of the two extreme orientations can achieve full stopping, and also form a bulk of hot, dense nuclear matter with a sufficiently large volume and long duration, due to the largely deformed uranium nuclei. The nucleon sideward flow in the tip-tip collisions is nearly 3 times larger than that in body-body ones at normalized impact parameter $b/b_{max}<0.5$, and that the body-body central collisions have a largest negative nucleon elliptic flow $v_{2}=-12%$ in contrast to zero in tip-tip ones. Thus the extreme circumstance and the novel experimental observables in tip-tip and body-body collisions can provide a good condition and sensitive probe to study the nuclear EoS, respectively. The Cooling Storage Ring (CSR) External Target Facility (ETF) to be built at Lanzhou, China, delivering the uranium beam up to 520 MeV/nucleon is expected to make significant contribution to explore the nuclear equation of state (EoS).