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Maxwell, T. J.

Paper Title Page
FRPMS035 Vector Diffraction Theory and Coherent Transition Radiation Interferometry in Electron Linacs 4015
 
  • T. J. Maxwell
  • C. L. Bohn, D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois
  
  Funding: Work supported by US. Department of Energy, under Contract No. DE-FG02-06ER41435 with Northern Illinois University

Electrons impinging on a thin metallic foil are seen to deliver small bursts of transition radiation (TR) as they cross the boundary from one medium to the next. A popular diagnostic application is found for compact electron bunches. In this case they will emit radiation more or less coherently with an N-squared enhancement of the intensity on wavelengths comparable to the bunch size, generating coherent transition radiation (CTR). Several detailed analytical descriptions have been proposed for describing the resulting spectral distribution, often making different simplifying assumptions. Given that bunches tenths of millimeters long can generate measurable spectra into the millimeter range, concern may arise as to weak diffraction effects produced by optical interference devices containing elements with dimensions in the centimeter range. The work presented here is a report on an upcoming graduate thesis exploring these effects as they apply to the Fermilab/NICADD photoinjector laboratory using a minimal C++ code that implements the methods of virtual quanta and vector diffraction theory.

 
FRPMS011 Design of an Electro-Optical Sampling Experiment at the AWA Facility 3901
 
  • J. Ruan
  • H. Edwards, V. E. Scarpine, C.-Y. Tan, R. Thurman-Keup
    Fermilab, Batavia, Illinois
  • YL. Li, J. G. Power
    ANL, Argonne, Illinois
  • T. J. Maxwell
    Northern Illinois University, DeKalb, Illinois
  
  Funding: Supported by US DOE

The free space electro-optical (EO) sampling technique is a powerful tool for analyzing the longitudinal charge density of an ultrashort e-beam. In this paper, we present

  1. experimental results for a laser-based mock-up of the EO experiment* and
  2. a design for a beam-based, single-shot, EO sampling experiment using the e-beam from the Argonne Wakefield Accelerator (AWA) RF photoinjector.
For the mock-up, a tabletop terahertz experiment is conducted in the AWA laser room. The mock-up uses an IR beam incident on <110> ZnTe crystal to produce a THz pulse via optical rectification. Detection is based on the cross correlation between the THz field and the probe IR laser field in a second <110> ZnTe crystal. Potential application of this technique to the ILC accelerator test facility at Fermilab is also presented.

* Yuelin Li, Appl. Phys. Lett. 88, 251108, 2006