Christopher Barnes, Franz-Josef Decker, Paul Emma, Mark Hogan, Rasmus Ischebeck, Richard Iverson, Patrick Krejcik, Caolionn O'Connell, Robert Siemann, Dieter Walz (SLAC, Menlo Park, California), Chris Clayton, Chengkun Huang, Devon K. Johnson, Chan Joshi, Wei Lu, Kenneth Marsh (UCLA, Los Angeles, California), Suzhi Deng, Tom Katsouleas, Patric Muggli, Erdem Oz (USC, Los Angeles, California)
In the E164 Experiment at that Stanford Linear Accelerator Center (SLAC),
we seek to drive plasma wakes for electron acceleration using 28.5 GeV bunches
from the main accelerator. These bunches can now be made with an RMS length
of less than 20 microns, and direct measurement is not feasible. Instead, we
use an indirect technique, measuring the energy spectrum at the end of the linac
and comparing with detailed simulations of the entire machine. We simulate with
LiTrack, a 2D code developed at SLAC which includes wakefields, synchrotron
radiation and all second order optical aberrations. Understanding the longitudinal
profile allows a better understanding of acceleration in the plasma wake, as
well as investigation of possible destructive transverse effects. We present
results from the July 2004 experimental run and show how this technique aids
in data analysis. We also discuss accuracy and validation of phase space determinations.