Physical Review Special Topics. Accelerators and Beams (Jul 2014)

Measurement of <20  fs bunch length using coherent transition radiation

  • I. Nozawa,
  • K. Kan,
  • J. Yang,
  • A. Ogata,
  • T. Kondoh,
  • M. Gohdo,
  • K. Norizawa,
  • H. Kobayashi,
  • H. Shibata,
  • S. Gonda,
  • Y. Yoshida

DOI
https://doi.org/10.1103/PhysRevSTAB.17.072803
Journal volume & issue
Vol. 17, no. 7
p. 072803

Abstract

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By monitoring coherent transition radiation (CTR) with a Michelson interferometer, bunch length measurement was investigated. Less-than-20-fs electron bunches were generated by a photocathode-based linear accelerator (linac) and a magnetic bunch compressor. From the femtosecond electron bunch of 2.1 pC and 32 MeV, CTR was measured using a Michelson interferometer that had two detectors with different spectral ranges, which enhanced the detection spectral range of CTR (ranging from 3 to 50 THz) and enabled us to determine the bunch length of the electron bunch. A model based on the interferometer’s frequency sensitivity was proposed and introduced to analyze the measured interferograms. The measured interferograms and the frequency spectra were explained using the model.