  The Event Plane Detector (EPD) is an upgrade detector to the STAR experiment
at RHIC, designed to measure the pattern of forward-going charged particles
emitted in a high-energy collision between heavy nuclei. It consists of two
highly-segmented disks of 1.2-cm-thick scintillator embedded with
wavelength-shifting fiber, coupled to silicon photomultipliers and custom
electronics. We describe the general design of the device, its construction,
and performance on the bench and in the experiment.
