Abstract-Observation of superradiant synchrotron radiation in the terahertz region

B. E. Billinghurst, J. C. Bergstrom, L. Dallin, M. de Jong, T. E. May, J. M. Vogt, and W. A. Wurtz
http://prst-ab.aps.org/accepted/27079Y7eF5c1d62839d606c1bd5fcc28232c2de54

We report the first high-resolution measurement of superradiance, using coherent synchrotron radiation in the terahertz region from the Canadian Light Source synchrotron and a Michelson interferometer with a nominal frequency resolution of 0.00096~cm$^{-1}$. Superradiance arises when a high degree of phase coherence exists between the radiation fields of the individual electron bunches, and manifests itself as a series of narrow spectral peaks at harmonics of the bunch frequency. We observe an enhancement factor of 16 at the spectral peaks, limited by the interferometer resolution. The spectral distribution and relative amplitudes of the superradiant peaks are modified by altering the pattern of bunches along the bunch train.