  This document presents BNL's plan for an electron-ion collider, eRHIC, a
major new research tool that builds on the existing RHIC facility to advance
the long-term vision for Nuclear Physics to discover and understand the
emergent phenomena of Quantum Chromodynamics (QCD), the fundamental theory of
the strong interaction that binds the atomic nucleus. We describe the
scientific requirements for such a facility, following up on the community-wide
2012 white paper, 'Electron-Ion Collider: the Next QCD Frontier', and present a
design concept that incorporates new, innovative accelerator techniques to
provide a cost-effective upgrade of RHIC with polarized electron beams
colliding with the full array of RHIC hadron beams. The new facility will
deliver electron-nucleon luminosity of 10^33-10^34 cm-1sec-1 for collisions of
15.9 GeV polarized electrons on either 250 GeV polarized protons or 100 GeV/u
heavy ion beams. The facility will also be capable of providing an electron
beam energy of 21.2 GeV, at reduced luminosity. We discuss the on-going R&D
effort to realize the project, and present key detector requirements and design
ideas for an experimental program capable of making the 'golden measurements'
called for in the EIC White Paper.
