Event plane determination from Zero Degree Calorimeter at the Cooling-Storage-Ring External-target Experiment

The Cooling-Storage-Ring External-target Experiment (CSR-CEE) is a spectrometer to study the nature of nuclear matter created in heavy ion collision at $\sqrt{s_{NN}} =$ 2.1 - 2.4 GeV, aiming to reveal Quantum Chromodynamics (QCD) phase structure in the high-baryon density region. Collective flow is regarded as an effective probe for studying the properties of the medium in high-energy nuclear collisions. One of the main functions of the Zero-Degree Calorimeter (ZDC), a sub-detector system in CEE, is to determine the reaction-plane in heavy ion collisions, which is crucial for the measurements of collective flow and other reaction plane related analysis. In this paper, we illustrate the procedures of event plane determination from ZDC. Finally, predictions of the rapidity dependence of directed and elliptic flow for $p$, $d$, $t$, $^3$He and $^4$He, from 2.1 GeV U+U collisions of IQMD model calculations, are presented.