A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z    

Emma, P.

Paper Title Page
MO2002 Energy Doubling in a Plasma Wakefield Accelerator 16
 
  • R. Ischebeck, M. K. Berry, I. Blumenfeld, F.-J. Decker, P. Emma, M. J. Hogan, R. H. Iverson, N. A. Kirby, P. Krejcik, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • S. Deng, T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  
  In the experiment E-167 at SLAC, the compressed electron pulse from the linac traverses a lithium vapor column and creates a plasma wake, which accelerates and focuses particles in the back of the pulse. Recent experimental results show that these fields can be sustained for 85 cm, increasing the particle energy from 42 GeV to 80 GeV. Plasma electrons can be trapped in the accelerating wake, resulting in ultra-short bunches with a relatively narrow energy spread and a small divergence angle. The results agree with three-dimensional particle-in-cell simulations.  
MOP026 Positron Source from X-rays Emitted by Plasma Betatron Motion 94
 
  • D. K. Johnson, C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • C. D. Barnes, I. Blumenfeld, F.-J. Decker, P. Emma, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. A. Kirby, P. Krejcik, C. L. O'Connell, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • S. Deng, T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  
  A new method for generating positrons has been proposed that uses betatron X-rays emitted by an electron beam in a high-K plasma wiggler. The plasma wiggler is an ion column produced by the head of the beam when the peak beam density exceeds the plasma density. The radial electric field of the beam blows out the plasma electrons transversely, creating an ion column. The focusing electric field of the ion column causes the beam electrons to execute betatron oscillations about the ion column axis. At the proper plasma density, this leads to synchrotron radiation in the 1-50 MeV range. These photons strike a thin (.5Xo), high-Z target and create electron-positron pairs. A computational model was written and matched with experimental results taken at the Stanford Linear Accelerator Center. This model was then used to design a more efficient positron source, giving positron yields of 0.44 positrons/electron, a number that is close to the target goal of 1-2 positrons/electron for future positron sources.  
TUP014 Electron Signal Detection for the Beam-Finder Wire of the Linac Coherent Light Source Undulator 274
 
  • J. Wu, P. Emma
    SLAC, Menlo Park, California
  
  The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. The tight tolerances for positioning the electron beam close to the undulator axis calls for the introduction of Beam Finder Wire (BFW) device. A BFW device close to the upstream end of the undulator segment and a quadrupole close to the down stream end of the undulator segment will allow a beam-based undulator segment alignment. Based on the scattering of the electrons on the BFW, we can detect the electron signal in the main dump bends after the undulator to find the beam position. We propose to use a threshold Cherenkov counter for this purpose. According to the signal strength at such a Cherenkov counter, we then suggest choice of material and size for such a BFW device in the undulator.  
TUP015 Linac Coherent Light Source (LCLS) Bunch-Length Monitor Using Coherent Radiation 277
 
  • J. Wu, P. Emma
    SLAC, Menlo Park, California
  
  The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. One of the most critical diagnostic devices is the bunch length monitor (BLM). We are planning to install BLM right after each compressor utilizing coherent radiation from the last bending magnet. We will calculate the signal strength, and simulate the signal propagation using well-accepted simulation tools in synchrotron radiation community in general, and THz radiation in particular. We will also discuss issues of optics layout, and detectors.  
TH1001 The Linac Coherent Light Source (LCLS) Accelerator 511
 
  • J. Wu, P. Emma
    SLAC, Menlo Park, California
  
  The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. Such an FEL requires a high energy, high brightness electron beam to drive the FEL instability to saturation. When fed by an RF-photocathode gun, and modified to include two bunch compressor chicanes, the SLAC linac will provide such a high quality beam at 14 GeV and 1-micron normalized emittance. In this talk, we report on recent linac studies, including beam stability and tolerances, longitudinal and transverse feedback systems, conventional and time-resolved diagnostics, and beam collimation systems. Construction and installation of the injector through first bunch compressor will be complete by November 2006, and electron commissioning is scheduled to begin in December of that year.