• D. Jeon, A.V. Aleksandrov, S. Assadi, W.P. Grice, Y. Liu, A.A. Menshov, J. Pogge, A. Webster
  ORNL, Oak Ridge, Tennessee
• I. Nesterenko
  BINP SB RAS, Novosibirsk

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

A transverse phase space emittance scanner is proposed and under development for the 1-GeV H^- SNS linac, using a laser beam as a slit. For a 1 GeV H^- beam, it is difficult to build a slit because the stopping distance is more than 50 cm in copper. We propose to use a laser beam as an effective slit by stripping off the outer electron of the H^- (making it neutral) upstream of a bend magnet and measuring the stripped component downstream of the bend magnet. The design and modeling of the system will be discussed. We are expecting to make a preliminary measurement in 2009.

• A. Novokhatski, S.A. Heifets
  SLAC, Menlo Park, California
• A.V. Aleksandrov
  ORNL, Oak Ridge, Tennessee

Funding: work supported by the Department of Energy under contract number DE-AC03-76SF00515 and DE-AC05

Fields induced by a beam and penetrated outside the beam pipe can be used for a beam diagnostic. Wires placed in longitudinal slots in the outside wall of the beam pipe can work as a beam pickup. This has a very small beam-coupling impedance and avoids complications of having a feed-through. The signal can be reasonably high at low frequencies. We calculate the beam-coupling impedance due to a long longitudinal slot in the resistive wall and the signal induced in a wire placed in such a slot and shielded by a thin screen from the beam. We present a field waveform at the outer side of a beam pipe, obtained as a result of calculations and measurements. Such kind of diagnostic can be used in storage rings, synchrotron light sources, and free electron lasers, like LINAC coherent light source.