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The Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is the world’s only dedicated nuclear collider. The collisions between nuclei traveling roughly 99.999% the speed of light create a medium more than 100,000 times hotter than the interior of the sun. This medium is an intensely energetic soup of quarks and gluons called the Quark Gluon Plasma (QGP), as it is hot enough to melt protons and neutrons so that quarks and gluons are no longer confined into hadrons. The QGP is a nearly perfect liquid, as its viscosity over entropy ratio is close to the theoretical minimum, and it has recently been found to have the highest vorticity ever measured. Starting in 2018 a Beam Energy Scan, where collisions over a wide variety of energies, will be performed at RHIC with the goal of mapping the phase diagram of the nuclear strong force, otherwise known as Quantum Chromodynamics (QCD). Understanding this phase diagram, and the location and existence of the phase transition between the QGP and normal hadronic matter is of fundamental importance, as this is a unique opportunity to learn how one of the four fundamental forces of nature operates at temperature and energy densities similar to those that existed only microseconds after the Big Bang. A new event plane detector (EPD), which can measure the impact parameter between colliding nuclei, will be installed in the Solenoidal Tracker at RHIC (STAR) experiment at the end of 2017. A prototype of the detector, consisting of a single sector was integrated into STAR during the 2016 run. The optimized segmentation, size and shape were finalized based on the prototype data in order to maximize event plane resolution, centrality estimation and flow harmonic measurements. One eighth of the detector was installed during the 2017 run for commissioning. I will focus on the design, construction and performance of the new detector, and how its precision will improve the systematics of a whole suite of observables.