• 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.

• J.K. Sekutowicz
  DESY, Hamburg
• P. Kneisel
  JLAB, Newport News, Virginia
• R. Nietubyc
  The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock
• T. Rao, J. Smedley
  BNL, Upton, Long Island, New York

In this contribution, we report Quantum Efficiency (QE) test results with a hybrid lead/niobium superconducting RF (SRF) photoinjector at 2K and new Pb arc deposited cathodes at 300K. The ultimate goal of our effort is to build a Nb injector with the superconducting cathode made of lead, which, as reported in the past, demonstrated superior QE compared to other metallic superconducting elements. At first, we present the test results obtained with a 1.6-cell high purity Nb cavity with the emitting lead spot in the center of the back plate. The QE test results at room temperature and the SEM surface analysis of eight Pb cathodes, deposited recently under various conditions, are discussed in the second part of this contribution.