An Improved Event Plane Detector for the STAR Experiment

These proceedings present the design, construction and engineering run status of the Event Plane Detector (EPD) upgrade at the STAR experiment. The EPD is a key detector for the upcoming beam energy scan (BES-II) program at the STAR experiment. During the first phase of the beam energy scan (BES-I), the STAR collaboration investigated observables as a of function beam energy in order to map the quantum chromodynamics (QCD) phase diagram. Some of these observables showed hints of non-monotonic behavior near the expected critical point location and first-order phase transition. But limited statistics, acceptance, and poor event plane resolution did not allow firm conclusions for a discovery. Therefore, BES-II has been approved, and STAR will take data in 2019 and 2020, with several detector and accelerator upgrades. The EPD is one such upgrade to the existing detector, which replaces the existing Beam-Beam Counter detector with larger granularity and acceptance. It can provide collision centrality measurements independent of the main tracking detectors. The EPD is capable of providing better event plane resolution and allows STAR to trigger on high luminosity collisions at lower energies, so that significant enhancements of measurements can be achieved.