Speaker
Description
The PHENIX experiment was operated at BNL-RHIC which collides heavy ions at
relativistic energy to create a quark-gluon plasma (QGP), in which quarks and gluons are deconfined. It is well known that the QGP produced in heavy ion collisions exhibits collective motion. In recent years, similar collective effect have been discovered in small systems at high energy collisions. This result attracts the attention to the multiple parton effect in nucleon such as Multi-Parton Interactions (MPI).
In this study, we attempt to observe the effect of multiple parton collisions in Au+Au at $\sqrt{s_{\textrm{NN}}}$ =200GeV. We assume that within an event selection with similar $N_{\textrm{part}}$, events with higher particle multiplicity would have more multiple parton collisions. In these events we would expect a large $v_2$ because of the larger energy density. In order to obtain $N_\textrm{part}$, we utilize the Zero Degree Calorimeter (ZDC) which detects the energies of spectator-neutrons. The particle multiplicity is measured in different rapidity ranges, with the Beam Beam Counter (BBC) at 3.1 < |η| < 3.9 and the Central Arm Tracking (CNT) at |η| < 0.35. In this poster, we will present the multiplicity dependence of
$v_2$ for several different ZDC selections. We also will discuss the rapidity dependence and the possible bias on the measurement.
