CERN Accelerating science

Article
Title	Background from Undulator in the Proposed Experiment with Polarized Positrons
Author(s)	Batygin, Y K
Affiliation	(SLAC, Stanford)
Publication	2004
In:	22nd International Linear Accelerator Conference, Lubeck, Germany, 16 - 20 Aug 2004, pp.123
Subject category	Accelerators and Storage Rings
Abstract	E-166 is a proposed experiment for verification of polarized positron production for linear collider. According to polarized positron source design, high energy electrons pass through helical undulator and produce circularly polarized photons, which interact with tungsten target and produce longitudinally polarized positrons. In the proposed E-166 experiment, 50 GeV beam propagates inside 1m long undulator followed by a drift space of 35 m before interaction with target. Polarized positrons are analyzed by Si-W calorimeter, which is placed along the axis. Polarized positrons are analyzed by CsI calorimeter after reconversion of positrons to photons at the second target. Background is an issue for a considered experiment. GEANT3 simulations were performed to model production of secondary particles from primary electrons hitting undulator. Energy density distribution of background particles at the target and effect of background collimation are discussed.