CERN Accelerating science

Article
Title	Femtosecond Electron Diffraction and its Application for Beam Characterization at the PAL
Author(s)	Xiang, Dao ; Ihee, Hyotcherl ; Park, Sung-Ju ; Soo Ko In ; Wang, Xijie
Affiliation	(BNL/NSLS, Upton, Long Island, New York) ; (KAIST, Daejeon) ; (PAL, Pohang) ; (TUB, Beijing)
Publication	2005
In:	21st IEEE Particle Accelerator Conference, Knoxville, TN, USA, 16 - 20 May 2005, pp.3721
Subject category	Accelerators and Storage Rings
Abstract	Electron diffraction is widely used in electron microscopy to obtain ultrahigh magnification factor, or crystallography to determine the internal structure of the molecule. High energy electron (MeV) has been used to probe the solid state thick sample, now being explored for femto-second electron diffraction (FED) to determine the transient structure of the molecule. We are proposing to perform FED using a photocathode RF gun at the Pohang Accelerator Laboratory (PAL), and develop an advanced electron beam diagnostic tool based on the electron diffraction. In this paper we will study how the diffraction pattern can be used to extract the information on the beam’s divergence. With a well-known sample, such as aluminum foil, whose internal structure is predetermined, the diffraction pattern for both single electron and the electron beam with a given divergence distribution can be calculated. Our proposed technique shows great potential of electron diffraction in beam divergence characterization. An experiment to verify the practicality of this method is under preparation and will be carried out at the proposed high brightness R&D facility at the PAL) in the near future.