• C. Sun, Y.K. Wu
  FEL/Duke University, Durham, North Carolina
• G. Rusev, A. Tonchev
  TUNL, Durham, North Carolina

A gamma-ray beam produced by Compton scattering of a laser beam with a relativistic electron beam has been used to determine the electron beam parameters. In the past, the electron beam energy and energy spread were directly fit from the high energy edge of a measured gamma beam spectrum using a gamma-ray detector. However, due to non-ideal response of the detector, the measured spectrum cannot represent the true energy distribution of the gamma-ray beam. Thus, the electron beam energy and energy spread could not be accurately determined from the measured gamma beam spectrum. In this paper, we will present a novel end-to-end spectrum reconstruction method to accurately extract the energy distribution of the gamma-ray beam from the measured gamma beam spectrum. Using this method we have accurately determined the energy and energy spread of the electron beam in Duke storage ring using a Compton gamma-ray beam from the High Intensity γ-ray Source (HIγS) facility.

• J. Zhang, J.Y. Li, C. Sun, W. Wu, Y.K. Wu
  FEL/Duke University, Durham, North Carolina
• A. Chao
  SLAC, Menlo Park, California

Funding: *Work supported by US Air Force Office of Scientific Research medical FEL grant FA9550-04-01-0086 (YKWu).

Touschek scattering is the dominant loss mechanism for the electron beam in a low energy storage ring with a large bunch current. The Duke Free-Electron Laser (FEL) storage ring typically operates in the one-bunch or two-bunch mode with a very high bunch current and a varying electron beam energy as low as 250 MeV. The study of the Touschek lifetime is important for improving the performance of the Duke storage ring based light sources, including the storage ring FELs and a FEL driven Compton gamma source, the High Intensity Gamma-ray Source. This work reports our lifetime measurement results for few-bunch operation of the Duke storage ring. The Touschek loss rate is reduced when an electron beam is polarized in the storage ring. The change of the Touschek lifetime can be used as a method to monitor polarization of the electron beam. In this work, we will also report our preliminary results of the electron beam energy measurements using the resonant depolarization technique.

• C. Sun, J.Y. Li, Y.K. Wu
  FEL/Duke University, Durham, North Carolina
• G. Rusev, A. Tonchev
  TUNL, Durham, North Carolina

A gamma-ray beam produced by Compton scattering of a laser beam and a relativistic electron beam has been used to determine electron beam parameters. In order to accurately measure the electron beam energy, a fitting model based upon Compton scattering cross section is introduced in this paper. With this model, we have successfully determined the energy of the electron beam in Duke storage ring with a relative uncertainty of 3× 10^-5 using a Compton gamma beam from the High Intensity γ-ray Source (HIγS) facility at Duke University.