• D. Trbojevic, J. Beebe-Wang, X. Chang, Y. Hao, A. Kayran, V. Litvinenko, B. Parker, V. Ptitsyn, N. Tsoupas
  BNL, Upton, Long Island, New York
• E. Pozdeyev
  FRIB, East Lansing, Michigan

We present a medium-energy (4 GeV) electron ion collider (MeRHIC) lattice design for the Relativistic Heavy Ion Collider (RHIC). MeRHIC represents a staged approach towards the higher energy eRHIC, with MeRHIC hardware being reused for eRHIC. The lattice design includes two Energy Recovery Linacs (ERLs), multiple isochronous arcs connected to the ERLs, an interaction region design, a low energy ERL with a polarized electron source, and connecting beam lines.

* V. Litvinenko, proceedings from this conference.

• Q. Wu, I. Ben-Zvi, X. Chang, J. Skarita
  BNL, Upton, Long Island, New York

The proposed electron ion collider, eRHIC, requires large average polarized electron current of 50mA, which is more than 20 times higher than the present experiment results of single polarization source, such as GaAs. To achieve the current requirement of eRHIC, we have designed the multi-cathode DC electron gun for injection. 24 GaAs cathodes will be prepared and emit electrons at the arranged pattern. Despite of ultra-high vacuum and precise timing, multi-cathode DC electron gun has high demand on the electric field symmetry, magnetic field shielding, and arcing prevention. In the paper, we present the 3D simulation results of the latest model for the multi-cathode DC electron gun. The results will give guidance to the actual design in the future.

• J. Smedley, I. Ben-Zvi, X. Chang, P.D. Johnson, J. Rameau, T. Rao, Q. Wu
  BNL, Upton, Long Island, New York
• J. Bohon
  Case Western Reserve University, Center for Synchrotron Biosciences, Upton, New York
• E.M. Muller
  Stony Brook University, Stony Brook

The diamond amplified photocathode has the potential to dramatically increase the average current available from photoinjectors, perhaps to the amphere-class performance necessary for flux-competitive fourth-generation light sources. Electron emission from a diamond amplifier has been observed from hydrogen-terminated diamond, using both photons and electrons to generate carriers. The diamond electron amplifier has been demonstrated, with an emission gain of 40. Very high average current densities (>10 A/cm²) have been transported through the diamond using x-ray generated carriers. The device relies on high-purity intrinsic diamond with low crystalline defect density, as well as a negative electron affinity achieved by hydrogen termination. The effects of diamond purity and crystalline defects on charge transport in the material, and emission from the diamond surface have been studied using a number of techniques and the process is now well understood. The electron affinity of diamond has been measured to be -1.1 eV; the fraction of the electrons produced in the material which are emitted from the surface has also been measured.