• C. Sun, J.Y. Li, S.F. Mikhailov, V. Popov, W. Wu, Y.K. Wu
  FEL/Duke University, Durham, North Carolina
• A. Chao
  SLAC, Menlo Park, California
• H. Xu, J. Zhang
  USTC/NSRL, Hefei, Anhui

Touschek lifetime of an electron beam in a storage ring depends on the beam polarization through the intrabeam scattering effect. Consequently, the electron beam polarization can be determined by comparing the measured Touschek lifetime of a polarized beam and an unpolarized beam. In this paper, we report a systematic experimental procedure to study the radiative polarization of a stored electron beam. Based upon this technique, we have successfully observed the polarization build-up of a 1.15 GeV electron beam in the Duke storage ring. Using the Touchek lifetime data, we are able to determine the equilibrium degree of the electron beam polarization and the time constant for the polarization build-up process.

• C. Sun, Y.K. Wu
  FEL/Duke University, Durham, North Carolina

Compton scattering of a laser beam with a relativistic electron beam has been used to generate an intense, highly polarized, and nearly monoenergetic gamma-ray beam at several facilities. The ability of predicting the spatial and spectral distributions of a Compton gamma-ray beam is crucial for the optimization of the operation of a Compton light source as well as for the applications utilizing the Compton beam. Based upon the Lorentz invariant Compton scattering cross section, we have derived an analytical formula to study the Compton scattering process. Using this formula, we have developed an integration code to produce the smooth results for the spatial and spectral distributions of the Compton beam. This code has been characterized at the High Intensity Gamma-ray Source (HIGS) facility at Duke University for varying electron and laser beam parameters as well as different gamma-ray beam collimation conditions.

• D. Robin, G.C. Pappas, C. Sun
  LBNL, Berkeley, California
• Z.K. Fisher
  MIT, Cambridge, Massachusetts

We have developed computer models for a pulsed-multipole magnet injection scheme for the Advanced Light Source (ALS) at Lawrence Berkeley National Lab. The multipole kicker injection scheme is further shown to be com- patible with the ALS in combination with a magnet lattice that has a low beta-function in the injection straight. Since traditional injection schemes are not compatible with such optimized low beta lattices, implementing the new injection scheme opens up several new possibilities. For instance, the adoption of a low beta lattice can greatly increase brightness due to the better matching of photon and electron beam emittances. This document explains the principles of the injection and the simulations we performed to show that the concept is sound.