• T.  Kamps, V. Duerr, K. Goldammer, D. Kraemer, P. Kuske, J. Kuszynski, D. Lipka, F. Marhauser, T. Quast, R. Richter
  BESSY GmbH, Berlin
• P. Evtushenko
  Jefferson Lab, Newport News, Virginia
• U. Lehnert, P. Michel, J. Teichert
  FZR, Dresden
• I. Will
  MBI, Berlin

Funding: Funded by the Bundesministerium für Bildung und Forschung, the State of Berlin and the Zukunftsfonds Berlin

A superconducting rf photo electron injector (SRF gun) is currently under construction by a collaboration between BESSY, DESY, FZR and MBI. The project aims at the design and setup of an CW SRF gun including a diagnostics beamline for the ELBE FEL and to address R&D issues on low emittance injectors for future light sources such as the BESSY FEL. Of critical importance for the injector performance is the control of the electron beam parameters. For this reason a compact diagnostics beamline is under development serving a multitude of operation settings ranging from low-charge (77pC), low-emittance (1 pi mm mrad) mode to high-charge (2.5nC) operation of the gun. For these operation modes beam dynamics simulations are resulting in boundary conditions for the beam instrumentation. Proven and mature technology is projected wherever possible, for example for current and beam position monitoring. The layout of the beam profile and emittance measurement systems is described. For the bunch length, which varies between 5 and 50 ps, two schemes using Electro-optical sampling and Cherenkov radiation are detailed. The beam energy and energy spread is measured with an especially designed 180 degree spectrometer.

• J. Teichert, A. Arnold, H. Buettig, D. Janssen, U. Lehnert, P. Michel, K. Moeller, P. Murcek, Ch. Schneider, R. Schurig, F. Staufenbiel, R. Xiang
  FZR, Dresden
• T.  Kamps, D. Lipka, F. Marhauser
  BESSY GmbH, Berlin
• W.-D. Lehmann
  IfE, Dresden
• J. Stephan
  IKST, Drsden
• V. Volkov
  BINP SB RAS, Novosibirsk
• I. Will
  MBI, Berlin

A superconducting rf photo electron injector (SRF gun) is under development at the Forschungszentrum Rossendorf. The project aims at several issues: improvement of the beam quality for the ELBE superconducting electron linac, demonstration of feasibility of this gun type, investigation of critical components, and parameter studies for future application (BESSY-FEL, 4GLS). In 2005, a substantial progress has been made. The two 3.5-cell niobium cavities for the gun have been delivered from the company ACCEL. The main parts for gun cryostat like vacuum vessel, cryogenic and magnetic shields are ready. Test benches for the cathode cooling system and the cavity tuner are being assembled. The photo cathode preparation lab has been arranged, and the diagnostic beam line has been designed (see T. Kamps et al., this conference). After delivering the gun cavities, their rf properties are being measured at room temperature and the warm tuning is being carried out. The set-up for this treatment and measurement as well as the results will be presented.