Conceptual design of a Polarized Electron Ion Collider at Brookhaven National Laboratory

To facilitate the SAC 2015 Long Range Plan for Nuclear Science: a high-energy high-luminosity polarized Electron-Ion Collider (EIC) as the highest priority for new facility construction following the completion of FRIB. Brookhaven National Laboratory (BNL) is proposing to build a high luminosity electron-hadron collider called e-RHIC which incorporates a new electron synchrotron with the existing Relativistic Heavy Ion Collider (RHIC). A low risk conventional technology based design is being adopted for the majority of the accelerator components. The e-RHIC electron source will produce a highly polarized beam current of up to 50 mA with > 80% polarization at an energy of up to 18 GeV with a luminosity > 1034 cm-2s-1. The prototype e-RHIC beam source is currently under development at BNL and Stony Brook University. This paper presents a conceptual design of the e-RHIC machine, how polarized beam will enhance the physics program and plans to address the remaining challenges associated with the construction of e-RHIC. In order to construct a future electron ion collider with high luminosity, a high average current and high bunch charge polarized electron source is under development at Brookhaven National Laboratory. We present the R&D plan for achieving the required charge and current in the polarized eRHIC gun.. The plan involves developing a large single cathode gun to generate 5.3 nC and 6 mA polarized electrons beam. We report the progress of large cathode prototype gun development, the beam line design and plan for measuring gun charge lifetime for high bunch charge, high current operation.