1. Before aperture After aperture Faraday Cup Trigger Photodiode Laser Energy Meter Phosphor Screen Solenoids Successful Initial X-Band Photoinjector Electron Beam Production Experiment Energy (MeV) 1.40 1.45 1.50 1.55 MeV 1.47 MeV sub-picosecond electron bunch produced with an energy spread of 1.8% at a gradient of over 100 MeV/m Cathode Quantum Efficiency = 2 x 10 -5 Normalized rms emittance = 1.63  mm- mrad Compton X-Ray Source Development A.E. Vlieks, D. Martin, G. Caryotakis Stanford Linear Accelerator Center D. Price Lawrence Livermore National Laboratory C. DeStefano, J.P. Heritage, E.C. Landahl, B. Pelletier, N.C. Luhmann, Jr. Departments of Applied Science and Electrical and Computer Engineering, University of California, Davis Linac Quadrupole Magnets Laser Feedthru / Electron Beam Diagnostics Waveguide from Klystron Solenoid and Photoinjector Linac Quadrupole Magnets Electron Beam Diagnostics Camera Waveguide Window Solenoid and Photoinjector Vacuum Pumpout Gate Valve Dipole Corrector Magnet Before aperture 6 ft Compton X-Ray Source Beamline Interaction parameters: Energy spread  < 1% Energy tunable 25 – 60 MeV Peak current 630 Amperes Emittance 1  mm-mrad Focal spot 20 micron diameter Cathode parameters: Ultraviolet laser 266 nm Flat-top duration 800 fs Electron bunch charge 500 pC Quantum efficiency 2 x 10 -5 Uniform emission radius 0.25 mm What is a photoinjector? Cu e-e- UV Laser light Photoelectric Effect + RF Acceleration 1.Emission of electrons from surface is characterized by laser pulse shape and intensity 2.Pulse can be very short. (  0.1-1 ps) 3.Current can be high. ( 0.5 nC charge  630 A for an 800 fs pulse) 4.Beam size can be small. Size is determined by laser pulse shape. 5.RF fields can be very high. (  200 MeV/m) X-band klystrons developed for the Next Linear Collider 11.424 GHz 1.5  s pulsewidth 60 MW output power 420 kV, 327 A Two klystrons used for CXS-10; however, the clinical device will use a single source X-band permits high gradients of up to 75 MV/m Four times smaller than conventional technology Focusing of ~ kA beam to 30 microns in < 2 meters Opens up a new energy and intensity frontier to the medical community Processing accelerator structure to 75 MV/m X-band 1.05 m long accelerator structure SLAC Compact X-band Accelerators and Microwave Power Sources Table-Top Terawatt Laser The same high field conditions that exist inside a synchrotron x-ray source are generated at the interaction point for only 5 x 10 -14 seconds Ultrashort optics techniques are utilized to synchronize and shape the laser for optimum electron beam and x-ray production 12 fs laser oscillator TW pulse compressor Operation of the First X- band Photoinjector (8.6 GHz) First Implementation of an Ultrashort Pulse Laser into a Photoinjector Production of Low Emittance and Low Energy Spread Electron Beams

2. Pre-bonding The X-Band Photoinjector: A New Source of High Brightness Electron Beams Electromagnetic Simulations Structure Bonding Final Mechanical Design and Fabrication Cold Tests Emittance Compensation Solenoid Magnet 6 5 4 3 2 1 248610014162018 12 Z (cm) Bz (kG) 3D HFSS modeling to adjust Q ext and frequency Bead-pull apparatus for cold testing of field profiles Waveguide Assembly Cold test photoinjector cavity Photoinjector cells in bonding furnace Individual Tuning of Final Cells Frequency Sensitivity: Cells 2-5 Cell 6 Cell 1 Endcaps Coax. antenna Waveguide Assembly Components Ceramic Window Power Splitter Pump-out port Cathode Water-cooling Input waveguide Beam Exit 1.RF Design.  2.Beam dynamics design.  3.Manufacture of cold-test parts.  4.Diffusion bonding of cold-test Injector.  5.Re-measurement of cold-test Injector.  6.Coupler redesign.  7.Manufacture of final Gun parts  8.Cold testing/tuning of final gun parts.  9.Assembly/diffusion bonding  10.High Power tests underway RF Gun 2D Electric Field Profile from SUPERFISH Post-bonding Field flatness maintained and frequency change quantified Final Bonded Photoinjector Cavity